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[PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. 559+ messages / 3 participants [nested] [flat]
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2024-08-27 10:13 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2024-08-27 10:13 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index ae676145e6..f96bafe5ec 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -579,10 +579,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -624,6 +621,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -634,7 +656,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -642,7 +664,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -659,11 +681,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 7d2b34d4f2..b8b500f48f 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -155,7 +155,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -570,7 +569,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index caa5113ff8..ad06e80784 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -69,6 +69,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 9398a84051..e7ac89f484 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -68,6 +68,7 @@ extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); extern Snapshot GetOldestSnapshot(void); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v02-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2024-09-04 10:29 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2024-09-04 10:29 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 0450f94ba8..4923e35e92 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -579,10 +579,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -624,6 +621,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -634,7 +656,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -642,7 +664,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -659,11 +681,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 7d2b34d4f2..b8b500f48f 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -155,7 +155,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -570,7 +569,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index caa5113ff8..ad06e80784 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -69,6 +69,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 9398a84051..e7ac89f484 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -68,6 +68,7 @@ extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); extern Snapshot GetOldestSnapshot(void); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v03-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2024-09-06 07:55 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2024-09-06 07:55 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 0450f94ba8..4923e35e92 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -579,10 +579,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -624,6 +621,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -634,7 +656,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -642,7 +664,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -659,11 +681,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 7d2b34d4f2..b8b500f48f 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -155,7 +155,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -570,7 +569,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index caa5113ff8..ad06e80784 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -69,6 +69,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 9398a84051..e7ac89f484 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -68,6 +68,7 @@ extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); extern Snapshot GetOldestSnapshot(void); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v04-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2024-10-09 07:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2024-10-09 07:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 0450f94ba8..4923e35e92 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -579,10 +579,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -624,6 +621,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -634,7 +656,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -642,7 +664,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -659,11 +681,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 7d2b34d4f2..b8b500f48f 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -155,7 +155,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -570,7 +569,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index caa5113ff8..ad06e80784 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -69,6 +69,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 9398a84051..e7ac89f484 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -68,6 +68,7 @@ extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); extern Snapshot GetOldestSnapshot(void); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v05-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2024-12-11 18:22 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2024-12-11 18:22 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index a6a4da3266..097dc82f6f 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index a1a0c2adeb..4c573b2ded 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -153,7 +153,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -536,7 +535,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 3c1454df99..cb2a400cdc 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index afc284e9c3..874c59b60d 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -61,6 +61,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v06-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-01-13 13:29 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-01-13 13:29 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). The VACUUM FULL / CLUSTER will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index bbedd3de31..84bf0503a5 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 8f1508b1ee..42bded373b 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -153,7 +153,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -532,7 +531,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e..6d4d2d1814 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be7164..147b190210 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.45.2 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v07-0004-Add-CONCURRENTLY-option-to-both-VACUUM-FULL-and-CLUS.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-02-26 08:17 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-02-26 08:17 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index bd0680dcbe..8c83ff6feb 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 8f1508b1ee..42bded373b 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -153,7 +153,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -532,7 +531,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e..6d4d2d1814 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be7164..147b190210 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.43.5 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v08-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v09 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-02-26 08:17 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-02-26 08:17 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b64e53de017..2c336b47fdb 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --v2l46qwn2nggemiy Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v09-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v10 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-03-24 19:08 Álvaro Herrera <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Álvaro Herrera @ 2025-03-24 19:08 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b64e53de017..e5d2a583ce6 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --w2lc3gf2kw4enm6y Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v10-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 2/9] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-03-31 13:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-03-31 13:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b64e53de017..e5d2a583ce6 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.43.5 --=-=-= Content-Type: text/x-diff Content-Disposition: attachment; filename=v11-0003-Move-the-recheck-branch-to-a-separate-function.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 2/9] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-04-01 11:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-04-01 11:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b64e53de017..e5d2a583ce6 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.43.5 --=-=-= Content-Type: text/x-diff Content-Disposition: attachment; filename=v12-0003-Move-the-recheck-branch-to-a-separate-function.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-04-11 09:13 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-04-11 09:13 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 0d7bddbe4ed..feaa3ac5ad4 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.43.5 --=-=-= Content-Type: text/x-diff Content-Disposition: attachment; filename=v13-0003-Move-the-recheck-branch-to-a-separate-function.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-09 10:00 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-09 10:00 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 0d7bddbe4ed..feaa3ac5ad4 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.43.5 --=-=-= Content-Type: text/x-diff Content-Disposition: attachment; filename=v14-0003-Move-the-recheck-branch-to-a-separate-function.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index adf18c397db..270f37ecadb 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/x-diff Content-Disposition: attachment; filename=v15-0003-Move-the-recheck-branch-to-a-separate-function.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-06-30 17:41 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-06-30 17:41 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ghyrlegy6t3fabqb Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v17-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 8532bfd27e5..6eaa40f6acf 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..70a6b8902d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -591,7 +590,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..147b190210a 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -60,6 +60,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.1 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v18-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --ecl2euvoqutt27wj Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v25-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-08-11 13:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-08-11 13:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 98ddee20929..a2f1803622c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 65561cc6bc3..bc7840052fe 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -212,7 +212,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -602,7 +601,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.39.5 --3q6txozlgl6t37td Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v20-0005-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-04 17:20 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-04 17:20 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 51 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..dcf32101c4c 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,6 +482,31 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the xip array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. This difference does has no impact on XidInMVCCSnapshot(). + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + /* allocate in transaction context */ newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +542,22 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v26-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-09 18:44 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-09 18:44 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/commands/cluster.c | 8 ++- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 5 files changed, 53 insertions(+), 17 deletions(-) diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 3afab656cd9..89f0b03a31c 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -70,8 +70,7 @@ typedef struct static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid, Oid userid, int options); -static void rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose); +static void rebuild_relation(Relation OldHeap, Relation index, bool verbose); static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose, bool *pSwapToastByContent, TransactionId *pFreezeXid, MultiXactId *pCutoffMulti); @@ -415,7 +414,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid, TransferPredicateLocksToHeapRelation(OldHeap); /* rebuild_relation does all the dirty work */ - rebuild_relation(cmd, OldHeap, index, verbose); + rebuild_relation(OldHeap, index, verbose); /* rebuild_relation closes OldHeap, and index if valid */ out: @@ -629,8 +628,7 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal) * On exit, they are closed, but locks on them are not released. */ static void -rebuild_relation(RepackCommand cmd, - Relation OldHeap, Relation index, bool verbose) +rebuild_relation(Relation OldHeap, Relation index, bool verbose) { Oid tableOid = RelationGetRelid(OldHeap); Oid accessMethod = OldHeap->rd_rel->relam; diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 6e18baa33cb..34bdd987478 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = (TransactionId *) palloc(sizeof(TransactionId) * GetMaxSnapshotXidCount()); @@ -495,7 +518,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -503,7 +526,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -520,11 +543,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 24f73a49d27..886060305f5 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v27-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2025-12-13 18:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2025-12-13 18:27 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index d6ab1e017eb..a3730804428 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 40a2e90e071..4cf32ffe833 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index 44031dcf6e3..6d4d2d1814c 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 604c1f90216..f65f83c85cd 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v28-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-08 16:47 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-08 16:47 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 57 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 50 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..95f230f8e9b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,33 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +517,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +525,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +542,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v29-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-12 16:30 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v30-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-22 08:23 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-22 08:23 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v31-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --r7amdyq3rmktb267 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v33-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-01-27 10:48 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-01-27 10:48 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v32-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v34-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-16 19:49 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-16 19:49 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; - return snap; + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; + + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --kmtyk4ln3767qrma Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v35-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. @ 2026-02-27 18:01 Antonin Houska <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Antonin Houska @ 2026-02-27 18:01 UTC (permalink / raw) The conversion is now handled by SnapBuildMVCCFromHistoric(). REPACK CONCURRENTLY will also need it. --- src/backend/replication/logical/snapbuild.c | 59 +++++++++++++++++---- src/backend/utils/time/snapmgr.c | 3 +- src/include/replication/snapbuild.h | 1 + src/include/utils/snapmgr.h | 1 + 4 files changed, 52 insertions(+), 12 deletions(-) diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 7f79621b57e..a738ad8a864 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -440,10 +440,7 @@ Snapshot SnapBuildInitialSnapshot(SnapBuild *builder) { Snapshot snap; - TransactionId xid; TransactionId safeXid; - TransactionId *newxip; - int newxcnt = 0; Assert(XactIsoLevel == XACT_REPEATABLE_READ); Assert(builder->building_full_snapshot); @@ -485,7 +482,35 @@ SnapBuildInitialSnapshot(SnapBuild *builder) MyProc->xmin = snap->xmin; - /* allocate in transaction context */ + /* Convert the historic snapshot to MVCC snapshot. */ + return SnapBuildMVCCFromHistoric(snap, true); +} + +/* + * Turn a historic MVCC snapshot into an ordinary MVCC snapshot. + * + * Unlike a regular (non-historic) MVCC snapshot, the 'xip' array of this + * snapshot contains not only running main transactions, but also their + * subtransactions. On the other hand, 'subxip' will usually be empty. This + * difference does not affect the result of XidInMVCCSnapshot() because it + * searches both in 'xip' and 'subxip'. + * + * Pass true for 'in_place' if you don't care about modifying the source + * snapshot. If you need a new instance, and one that was allocated as a + * single chunk of memory, pass false. + */ +Snapshot +SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place) +{ + TransactionId xid; + TransactionId *oldxip = snapshot->xip; + uint32 oldxcnt = snapshot->xcnt; + TransactionId *newxip; + int newxcnt = 0; + Snapshot result; + + Assert(snapshot->snapshot_type == SNAPSHOT_HISTORIC_MVCC); + newxip = palloc_array(TransactionId, GetMaxSnapshotXidCount()); /* @@ -494,7 +519,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * classical snapshot by marking all non-committed transactions as * in-progress. This can be expensive. */ - for (xid = snap->xmin; NormalTransactionIdPrecedes(xid, snap->xmax);) + for (xid = snapshot->xmin; NormalTransactionIdPrecedes(xid, snapshot->xmax);) { void *test; @@ -502,7 +527,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder) * Check whether transaction committed using the decoding snapshot * meaning of ->xip. */ - test = bsearch(&xid, snap->xip, snap->xcnt, + test = bsearch(&xid, snapshot->xip, snapshot->xcnt, sizeof(TransactionId), xidComparator); if (test == NULL) @@ -519,11 +544,25 @@ SnapBuildInitialSnapshot(SnapBuild *builder) } /* adjust remaining snapshot fields as needed */ - snap->snapshot_type = SNAPSHOT_MVCC; - snap->xcnt = newxcnt; - snap->xip = newxip; + snapshot->xcnt = newxcnt; + snapshot->xip = newxip; + + if (in_place) + result = snapshot; + else + { + result = CopySnapshot(snapshot); + + /* Restore the original values so the source is intact. */ + snapshot->xip = oldxip; + snapshot->xcnt = oldxcnt; + + /* newxip has been copied */ + pfree(newxip); + } + result->snapshot_type = SNAPSHOT_MVCC; - return snap; + return result; } /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 2e6197f5f35..3af1b366adf 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -213,7 +213,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static Snapshot CopySnapshot(Snapshot snapshot); static void UnregisterSnapshotNoOwner(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -604,7 +603,7 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, * The copy is palloc'd in TopTransactionContext and has initial refcounts set * to 0. The returned snapshot has the copied flag set. */ -static Snapshot +Snapshot CopySnapshot(Snapshot snapshot) { Snapshot newsnap; diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h index ccded021433..34383dea776 100644 --- a/src/include/replication/snapbuild.h +++ b/src/include/replication/snapbuild.h @@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder); extern void SnapBuildSnapDecRefcount(Snapshot snap); extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder); +extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place); extern const char *SnapBuildExportSnapshot(SnapBuild *builder); extern void SnapBuildClearExportedSnapshot(void); extern void SnapBuildResetExportedSnapshotState(void); diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index b8c01a291a1..de824945f0b 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -63,6 +63,7 @@ extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); +extern Snapshot CopySnapshot(Snapshot snapshot); extern Snapshot GetCatalogSnapshot(Oid relid); extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid); extern void InvalidateCatalogSnapshot(void); -- 2.47.3 --=-=-= Content-Type: text/plain Content-Disposition: attachment; filename=v36-0004-Add-CONCURRENTLY-option-to-REPACK-command.patch ^ permalink raw reply [nested|flat] 559+ messages in thread
* [PATCH v4 1/2] Support changing a column into a stored generated column @ 2026-05-14 21:51 Alberto Piai <[email protected]> 0 siblings, 0 replies; 559+ messages in thread From: Alberto Piai @ 2026-05-14 21:51 UTC (permalink / raw) This adds an ALTER TABLE subcommand to turn a regular column into a stored generated column: ... ALTER COLUMN c ADD GENERATED ALWAYS as (expr) STORED The syntax is chosen to be similar to ... ALTER COLUMN ... ADD GENERATED ... AS IDENTITY with the difference that in this case, since we're dealing with a generated column, only ALWAYS is supported. Additionally, STORED must always be specified. This new operation fits together with SET EXPRESSION and DROP EXPRESSION. Phase 2 happens in the same pass as the former, in order to run the cleanup code in ATPostAlterTypeCleanup, without which for example we would not re-check constraints when rewriting the table. Partitioning/inheritance is supported in the same way as DROP EXPRESSION: it is allowed to change the whole inheritace tree to/from a generated column at once; it is forbidden to change the parent table ONLY and it is forbidden to change a partition directly. See 8bf6ec3ba3a44448817af47a080587f3b71bee08 and the associated discussion. There is one limitation: currently DROP EXPRESSION does not allow to change an inheritance tree of depth > 2. This seems like an oversight, but in order to not feature-creep this commit, this is postponed for later; it should then be fixed for both DROP EXPRESSION and this new command. This is mostly useful as a first step to be able to add a stored generated column without rewriting the table under an exclusive lock. For ease of review, the operation as of this commit always rewrites the contents of the column using the new generated expression. --- src/backend/commands/tablecmds.c | 194 ++++++++++++++++- src/backend/parser/gram.y | 31 +++ src/include/nodes/parsenodes.h | 1 + .../test_ddl_deparse/test_ddl_deparse.c | 3 + src/test/regress/expected/alter_table.out | 200 ++++++++++++++++++ src/test/regress/sql/alter_table.sql | 142 +++++++++++++ 6 files changed, 570 insertions(+), 1 deletion(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..39faef0a114 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -783,6 +783,14 @@ static void ATExecMergePartitions(List **wqueue, AlteredTableInfo *tab, Relation static void ATExecSplitPartition(List **wqueue, AlteredTableInfo *tab, Relation rel, PartitionCmd *cmd, AlterTableUtilityContext *context); +static void ATPrepAddGeneratedAsExprStored(Relation rel, + AlterTableCmd *cmd, + bool recurse, bool recursing, + LOCKMODE lockmode); +static ObjectAddress ATExecAddGeneratedAsExprStored(AlteredTableInfo *tab, + Relation rel, + const char *colName, + Constraint *def); static List *collectPartitionIndexExtDeps(List *partitionOids); static void applyPartitionIndexExtDeps(Oid newPartOid, List *extDepState); static void freePartitionIndexExtDeps(List *extDepState); @@ -4769,6 +4777,7 @@ AlterTableGetLockLevel(List *cmds) case AT_AddIdentity: case AT_DropIdentity: case AT_SetIdentity: + case AT_AddGeneratedAsExprStored: case AT_SetExpression: case AT_DropExpression: case AT_SetCompression: @@ -5093,6 +5102,13 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context); pass = AT_PASS_SET_EXPRESSION; break; + case AT_AddGeneratedAsExprStored: + ATSimplePermissions(cmd->subtype, rel, + ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE); + ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context); + ATPrepAddGeneratedAsExprStored(rel, cmd, recurse, recursing, lockmode); + pass = AT_PASS_SET_EXPRESSION; + break; case AT_DropExpression: /* ALTER COLUMN DROP EXPRESSION */ ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_PARTITIONED_TABLE | ATT_FOREIGN_TABLE); @@ -5487,6 +5503,12 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, case AT_SetExpression: address = ATExecSetExpression(tab, rel, cmd->name, cmd->def, lockmode); break; + case AT_AddGeneratedAsExprStored: + Assert(IsA(cmd->def, Constraint)); + address = ATExecAddGeneratedAsExprStored(tab, rel, + cmd->name, + (Constraint *) cmd->def); + break; case AT_DropExpression: address = ATExecDropExpression(rel, cmd->name, cmd->missing_ok, lockmode); break; @@ -6695,6 +6717,8 @@ alter_table_type_to_string(AlterTableType cmdtype) return "ALTER COLUMN ... SET NOT NULL"; case AT_SetExpression: return "ALTER COLUMN ... SET EXPRESSION"; + case AT_AddGeneratedAsExprStored: + return "ALTER COLUMN ... ADD GENERATED ALWAYS AS (...) STORED"; case AT_DropExpression: return "ALTER COLUMN ... DROP EXPRESSION"; case AT_SetStatistics: @@ -8851,6 +8875,172 @@ ATExecSetExpression(AlteredTableInfo *tab, Relation rel, const char *colName, return address; } +/* + * Preparation for + * + * ALTER TABLE ALTER COLUMN ADD GENERATED ALWAYS AS expr STORED + * + * Checks whether recursion is allowed, following the same logic as ATPrepDropExpression. + */ +static void +ATPrepAddGeneratedAsExprStored(Relation rel, + AlterTableCmd *cmd, + bool recurse, bool recursing, + LOCKMODE lockmode) +{ + /* + * Reject ONLY if there are child tables. See ATPrepDropExpression. + */ + if (!recurse && + find_inheritance_children(RelationGetRelid(rel), lockmode)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("ALTER TABLE / ADD GENERATED ALWAYS AS (expr) STORED must be applied to child tables too"))); + + /* + * Cannot change only inherited columns to be stored generated columns. + */ + if (!recursing) + { + HeapTuple tuple; + Form_pg_attribute attTup; + + tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), cmd->name); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_COLUMN), + errmsg("column \"%s\" of relation \"%s\" does not exist", + cmd->name, RelationGetRelationName(rel)))); + + attTup = (Form_pg_attribute) GETSTRUCT(tuple); + + if (attTup->attinhcount > 0) + ereport(ERROR, + (errcode(ERRCODE_INVALID_TABLE_DEFINITION), + errmsg("cannot change inherited column to be a stored generated column"))); + } +} + +/* + * ALTER TABLE ALTER COLUMN ADD GENERATED ALWAYS AS expr STORED + */ +static ObjectAddress +ATExecAddGeneratedAsExprStored(AlteredTableInfo *tab, + Relation rel, + const char *colName, + Constraint *def) +{ + HeapTuple tuple; + Form_pg_attribute attTup; + AttrNumber attnum; + ObjectAddress address; + NewColumnValue *newval; + RawColumnDefault *rawEnt; + Relation pg_attribute; + List *newcons; + CookedConstraint *cookedDef; + + Assert(def->raw_expr != NULL); + Assert(def->cooked_expr == NULL); + Assert(def->generated_when == ATTRIBUTE_IDENTITY_ALWAYS); + Assert(def->generated_kind == ATTRIBUTE_GENERATED_STORED); + + tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_COLUMN), + errmsg("column \"%s\" of relation \"%s\" does not exist", + colName, RelationGetRelationName(rel)))); + + attTup = (Form_pg_attribute) GETSTRUCT(tuple); + + attnum = attTup->attnum; + if (attnum <= 0) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot alter system column \"%s\"", + colName))); + + if (attTup->attgenerated) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("column \"%s\" of relation \"%s\" is already a generated column", + colName, RelationGetRelationName(rel)))); + + /* + * Find everything that depends on the column (constraints, indexes, etc), + * and record enough information to let us recreate the objects. + */ + RememberAllDependentForRebuilding(tab, AT_AddGeneratedAsExprStored, + rel, attnum, colName); + + /* Mark as generated stored in pg_attribute */ + pg_attribute = table_open(AttributeRelationId, RowExclusiveLock); + attTup->attgenerated = ATTRIBUTE_GENERATED_STORED; + CatalogTupleUpdate(pg_attribute, &tuple->t_self, tuple); + table_close(pg_attribute, RowExclusiveLock); + + /* Make above changes visible */ + CommandCounterIncrement(); + + ReleaseSysCache(tuple); + + /* + * Remove previous default value, if any, and store the new generator + * expression. + */ + RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, + false, false); + + rawEnt = palloc_object(RawColumnDefault); + rawEnt->attnum = attnum; + rawEnt->raw_default = def->raw_expr; + rawEnt->generated = def->generated_kind; + newcons = AddRelationNewConstraints(rel, list_make1(rawEnt), + NIL, false, true, false, NULL); + + /* Make above changes visible */ + CommandCounterIncrement(); + + /* + * At the moment, AddRelationNewConstraints always returns one element + * when called with a generated = STORED input, but guard against + * accessing an empty list anyway. + */ + if (list_length(newcons) < 1) + ereport(ERROR, + errmsg_internal("expected exactly one processed default value")); + + cookedDef = linitial(newcons); + + /* + * Clear all the missing values if we're rewriting the table, since this + * renders them pointless. + */ + RelationClearMissing(rel); + + /* Make above changes visible */ + CommandCounterIncrement(); + + /* Drop any pg_statistic entry for the column */ + RemoveStatistics(RelationGetRelid(rel), attnum); + + /* Schedule a rewrite */ + newval = palloc0_object(NewColumnValue); + newval->attnum = attnum; + newval->expr = (Expr *) cookedDef->expr; + newval->is_generated = true; + tab->newvals = lappend(tab->newvals, newval); + tab->rewrite |= AT_REWRITE_DEFAULT_VAL; + + InvokeObjectPostAlterHook(RelationRelationId, + RelationGetRelid(rel), attnum); + + ObjectAddressSubSet(address, RelationRelationId, + RelationGetRelid(rel), attnum); + return address; +} + /* * ALTER TABLE ALTER COLUMN DROP EXPRESSION */ @@ -15320,7 +15510,9 @@ RememberAllDependentForRebuilding(AlteredTableInfo *tab, AlterTableType subtype, SysScanDesc scan; HeapTuple depTup; - Assert(subtype == AT_AlterColumnType || subtype == AT_SetExpression); + Assert(subtype == AT_AlterColumnType + || subtype == AT_SetExpression + || subtype == AT_AddGeneratedAsExprStored); depRel = table_open(DependRelationId, RowExclusiveLock); diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index ff4e1388c55..8cd75572257 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -2725,6 +2725,37 @@ alter_table_cmd: n->name = $3; n->def = (Node *) c; + $$ = (Node *) n; + } + /* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ALWAYS AS ( <expression> ) STORED */ + | ALTER opt_column ColId ADD_P GENERATED generated_when AS '(' a_expr ')' STORED + { + AlterTableCmd *n = makeNode(AlterTableCmd); + Constraint *c = makeNode(Constraint); + + c->contype = CONSTR_GENERATED; + c->generated_when = $6; + c->raw_expr = $9; + c->cooked_expr = NULL; + c->generated_kind = ATTRIBUTE_GENERATED_STORED; + c->location = @5; + + /* + * Like in the case of ColConstraintElem, we cannot handle + * this in the grammar because IDENTITY allows both ALWAYS + * and BY DEFAULT, while generated columns only allow + * ALWAYS. This would lead to shift/reduce conflicts. + */ + if (c->generated_when != ATTRIBUTE_IDENTITY_ALWAYS) + ereport(ERROR, + (errcode(ERRCODE_SYNTAX_ERROR), + errmsg("for a generated column, GENERATED ALWAYS must be specified"), + parser_errposition(@6))); + + n->subtype = AT_AddGeneratedAsExprStored; + n->name = $3; + n->def = (Node *) c; + $$ = (Node *) n; } /* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */ diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 91377a6cde3..620e2dd73bf 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -2527,6 +2527,7 @@ typedef enum AlterTableType AT_CookedColumnDefault, /* add a pre-cooked column default */ AT_DropNotNull, /* alter column drop not null */ AT_SetNotNull, /* alter column set not null */ + AT_AddGeneratedAsExprStored, /* add generated always as (...) stored */ AT_SetExpression, /* alter column set expression */ AT_DropExpression, /* alter column drop expression */ AT_SetStatistics, /* alter column set statistics */ diff --git a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c index 64a1dfa9f79..3132ceac61f 100644 --- a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c +++ b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c @@ -129,6 +129,9 @@ get_altertable_subcmdinfo(PG_FUNCTION_ARGS) case AT_SetNotNull: strtype = "SET NOT NULL"; break; + case AT_AddGeneratedAsExprStored: + strtype = "ADD GENERATED ALWAYS AS (...) STORED"; + break; case AT_SetExpression: strtype = "SET EXPRESSION"; break; diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 6dd22be0e8d..2d0ce414d12 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -4875,3 +4875,203 @@ drop publication pub1; drop schema alter1 cascade; drop schema alter2 cascade; NOTICE: drop cascades to table alter2.t1 +-- Tests for ALTER COLUMN ... ADD GENERATED ALWAYS as ( expr ) STORED +-- turning a regular column into a stored generated column +create schema testgen; +create table testgen.t1 (a int, b int not null); +insert into testgen.t1 (a, b) + select x, x from generate_series(1, 10) x; +alter table testgen.t1 alter column b + add generated always as (a * 2) stored; +\d+ testgen.t1 + Table "testgen.t1" + Column | Type | Collation | Nullable | Default | Storage | Stats target | Description +--------+---------+-----------+----------+------------------------------------+---------+--------------+------------- + a | integer | | | | plain | | + b | integer | | not null | generated always as (a * 2) stored | plain | | +Not-null constraints: + "t1_b_not_null" NOT NULL "b" + +select a, b, a * 2 as expected, b = (a * 2) as correct + from testgen.t1 order by a; + a | b | expected | correct +----+----+----------+--------- + 1 | 2 | 2 | t + 2 | 4 | 4 | t + 3 | 6 | 6 | t + 4 | 8 | 8 | t + 5 | 10 | 10 | t + 6 | 12 | 12 | t + 7 | 14 | 14 | t + 8 | 16 | 16 | t + 9 | 18 | 18 | t + 10 | 20 | 20 | t +(10 rows) + +insert into testgen.t1 (a, b) values (10, 20); +ERROR: cannot insert a non-DEFAULT value into column "b" +DETAIL: Column "b" is a generated column. +insert into testgen.t1 (a, b) values (10, 21); +ERROR: cannot insert a non-DEFAULT value into column "b" +DETAIL: Column "b" is a generated column. +drop table testgen.t1; +-- turning a regular column into a stored generated column +-- fails when another constraint conflicts with the new expression +create table testgen.t2 (a int, b int not null); +insert into testgen.t2 (a, b) select x, x * 2 from generate_series(0, 5) x; +alter table testgen.t2 add constraint chk_gen_clause check (b = a * 2); +select pg_relation_filenode('testgen.t2') as t2_filenode_before \gset +alter table testgen.t2 alter column b add generated always as (a * 3) stored; +ERROR: check constraint "chk_gen_clause" of relation "t2" is violated by some row +select pg_relation_filenode('testgen.t2') as t2_filenode_after \gset +select :t2_filenode_before = :t2_filenode_after as did_not_rewrite; + did_not_rewrite +----------------- + t +(1 row) + +\d+ testgen.t2 + Table "testgen.t2" + Column | Type | Collation | Nullable | Default | Storage | Stats target | Description +--------+---------+-----------+----------+---------+---------+--------------+------------- + a | integer | | | | plain | | + b | integer | | not null | | plain | | +Check constraints: + "chk_gen_clause" CHECK (b = (a * 2)) +Not-null constraints: + "t2_b_not_null" NOT NULL "b" + +drop table testgen.t2; +-- rewrite an indexed column +create table testgen.t3 (a int, b int); +create index idx_b on testgen.t3 (b); +insert into testgen.t3 (a, b) select x, x from generate_series(1, 10) x; +select pg_relation_filenode('testgen.idx_b') as idx_filenode_before \gset +alter table testgen.t3 alter column b add generated always as (a * 2) stored; +select pg_relation_filenode('testgen.idx_b') as idx_filenode_after \gset +select :idx_filenode_before != :idx_filenode_after as did_rewrite_idx; + did_rewrite_idx +----------------- + t +(1 row) + +drop table testgen.t3; +-- test support for partitioned tables and inheritance +create table testgen.tpart (a int, b int) partition by hash (a); +create table testgen.tpart_p1 partition of testgen.tpart + for values with (modulus 2, remainder 0); +create table testgen.tpart_p2 partition of testgen.tpart + for values with (modulus 2, remainder 1); +insert into testgen.tpart (a, b) select x, x from generate_series(1, 5) x; +-- altering the parent table, recursing +begin; +alter table testgen.tpart alter column b + add generated always as (a * 2) stored; +-- expected: all the partitions have been rewritten +select a, b, a * 2 as expected, b = (a * 2) as correct +from testgen.tpart_p1 order by a; + a | b | expected | correct +---+---+----------+--------- + 1 | 2 | 2 | t + 2 | 4 | 4 | t +(2 rows) + +select a, b, a * 2 as expected, b = (a * 2) as correct +from testgen.tpart_p2 order by a; + a | b | expected | correct +---+----+----------+--------- + 3 | 6 | 6 | t + 4 | 8 | 8 | t + 5 | 10 | 10 | t +(3 rows) + +rollback; +-- altering a single partition is not allowed +begin; +-- expected: error +alter table testgen.tpart_p1 alter column b + add generated always as (a * 2) stored; +ERROR: cannot change inherited column to be a stored generated column +rollback; +-- altering only the parent table is not allowed +begin; +-- expected: error +alter table only testgen.tpart alter column b + add generated always as (a * 2) stored; +ERROR: ALTER TABLE / ADD GENERATED ALWAYS AS (expr) STORED must be applied to child tables too +rollback; +drop table testgen.tpart; +-- subpartitions +create table testgen.tpart (a int, b int, c int) + partition by hash (a); +create table testgen.tpart_p1 partition of testgen.tpart + for values with (modulus 2, remainder 0) + partition by hash (b); +create table testgen.tpart_p1_1 partition of testgen.tpart_p1 + for values with (modulus 2, remainder 0); +create table testgen.tpart_p1_2 partition of testgen.tpart_p1 + for values with (modulus 2, remainder 1); +create table testgen.tpart_p2 partition of testgen.tpart + for values with (modulus 2, remainder 1) + partition by hash (b); +create table testgen.tpart_p2_1 partition of testgen.tpart_p2 + for values with (modulus 2, remainder 0); +create table testgen.tpart_p2_2 partition of testgen.tpart_p2 + for values with (modulus 2, remainder 1); +insert into testgen.tpart (a, b) +select x, y +from generate_series(1, 5) x + cross join generate_series(1, 5) y; +-- currently, it is not possible to change the generated state of an +-- inheritance tree of depth >= 2 (same as in DROP EXPRESSION), so we expect an +-- error here. This might be fixed later. +begin; +alter table testgen.tpart alter column c + add generated always as (a + b) stored; +ERROR: ALTER TABLE / ADD GENERATED ALWAYS AS (expr) STORED must be applied to child tables too +rollback; +drop table testgen.tpart; +-- tests for invalid invocations +alter table doesnotexist alter column foo + add generated always as (bar * 2) stored; +ERROR: relation "doesnotexist" does not exist +create table testgen.t1 (a int); +alter table testgen.t1 alter column doesnotexist + add generated always as (bar * 2) stored; +ERROR: column "doesnotexist" of relation "t1" does not exist +alter table testgen.t1 add column b int; +alter table testgen.t1 alter column b + add generated always as (doesnotexist * 2) stored; +ERROR: column "doesnotexist" does not exist +-- invalid: only supports ALWAYS +alter table testgen.t1 alter column b + add generated by default as (a * 2) stored; +ERROR: for a generated column, GENERATED ALWAYS must be specified +LINE 2: add generated by default as (a * 2) stored; + ^ +-- invalid: only supports STORED +alter table testgen.t1 alter column b add generated always as (a * 2); +ERROR: syntax error at or near ";" +LINE 1: ...e testgen.t1 alter column b add generated always as (a * 2); + ^ +alter table testgen.t1 alter column b add generated always as (a * 2) virtual; +ERROR: syntax error at or near "virtual" +LINE 1: ...n.t1 alter column b add generated always as (a * 2) virtual; + ^ +-- invalid: b is already a generated column +create table testgen.t2 (a int, b int generated always as (a * 2) stored); +alter table testgen.t2 alter column b add generated always as (a * 2) stored; +ERROR: column "b" of relation "t2" is already a generated column +drop table testgen.t2; +create table testgen.t3 (a int, b int); +-- invalid: expr must be immutable +alter table testgen.t3 alter column b + add generated always as (a + random()) stored; +ERROR: generation expression is not immutable +-- invalid: expr cannot use subselects +alter table testgen.t3 alter column b + add generated always as (a + (select 1)) stored; +ERROR: cannot use subquery in column generation expression +drop table testgen.t3; +drop schema testgen cascade; +NOTICE: drop cascades to table testgen.t1 diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql index f5f13bbd3e7..51d818d4995 100644 --- a/src/test/regress/sql/alter_table.sql +++ b/src/test/regress/sql/alter_table.sql @@ -3159,3 +3159,145 @@ alter table alter1.t1 set schema alter2; drop publication pub1; drop schema alter1 cascade; drop schema alter2 cascade; + +-- Tests for ALTER COLUMN ... ADD GENERATED ALWAYS as ( expr ) STORED +-- turning a regular column into a stored generated column +create schema testgen; + +create table testgen.t1 (a int, b int not null); +insert into testgen.t1 (a, b) + select x, x from generate_series(1, 10) x; +alter table testgen.t1 alter column b + add generated always as (a * 2) stored; +\d+ testgen.t1 +select a, b, a * 2 as expected, b = (a * 2) as correct + from testgen.t1 order by a; +insert into testgen.t1 (a, b) values (10, 20); +insert into testgen.t1 (a, b) values (10, 21); +drop table testgen.t1; + +-- turning a regular column into a stored generated column +-- fails when another constraint conflicts with the new expression +create table testgen.t2 (a int, b int not null); +insert into testgen.t2 (a, b) select x, x * 2 from generate_series(0, 5) x; +alter table testgen.t2 add constraint chk_gen_clause check (b = a * 2); +select pg_relation_filenode('testgen.t2') as t2_filenode_before \gset +alter table testgen.t2 alter column b add generated always as (a * 3) stored; +select pg_relation_filenode('testgen.t2') as t2_filenode_after \gset +select :t2_filenode_before = :t2_filenode_after as did_not_rewrite; +\d+ testgen.t2 +drop table testgen.t2; + +-- rewrite an indexed column +create table testgen.t3 (a int, b int); +create index idx_b on testgen.t3 (b); +insert into testgen.t3 (a, b) select x, x from generate_series(1, 10) x; +select pg_relation_filenode('testgen.idx_b') as idx_filenode_before \gset +alter table testgen.t3 alter column b add generated always as (a * 2) stored; +select pg_relation_filenode('testgen.idx_b') as idx_filenode_after \gset +select :idx_filenode_before != :idx_filenode_after as did_rewrite_idx; +drop table testgen.t3; + +-- test support for partitioned tables and inheritance +create table testgen.tpart (a int, b int) partition by hash (a); +create table testgen.tpart_p1 partition of testgen.tpart + for values with (modulus 2, remainder 0); +create table testgen.tpart_p2 partition of testgen.tpart + for values with (modulus 2, remainder 1); +insert into testgen.tpart (a, b) select x, x from generate_series(1, 5) x; + +-- altering the parent table, recursing +begin; +alter table testgen.tpart alter column b + add generated always as (a * 2) stored; +-- expected: all the partitions have been rewritten +select a, b, a * 2 as expected, b = (a * 2) as correct +from testgen.tpart_p1 order by a; +select a, b, a * 2 as expected, b = (a * 2) as correct +from testgen.tpart_p2 order by a; +rollback; + +-- altering a single partition is not allowed +begin; +-- expected: error +alter table testgen.tpart_p1 alter column b + add generated always as (a * 2) stored; +rollback; + +-- altering only the parent table is not allowed +begin; +-- expected: error +alter table only testgen.tpart alter column b + add generated always as (a * 2) stored; +rollback; + +drop table testgen.tpart; + +-- subpartitions +create table testgen.tpart (a int, b int, c int) + partition by hash (a); +create table testgen.tpart_p1 partition of testgen.tpart + for values with (modulus 2, remainder 0) + partition by hash (b); +create table testgen.tpart_p1_1 partition of testgen.tpart_p1 + for values with (modulus 2, remainder 0); +create table testgen.tpart_p1_2 partition of testgen.tpart_p1 + for values with (modulus 2, remainder 1); +create table testgen.tpart_p2 partition of testgen.tpart + for values with (modulus 2, remainder 1) + partition by hash (b); +create table testgen.tpart_p2_1 partition of testgen.tpart_p2 + for values with (modulus 2, remainder 0); +create table testgen.tpart_p2_2 partition of testgen.tpart_p2 + for values with (modulus 2, remainder 1); +insert into testgen.tpart (a, b) +select x, y +from generate_series(1, 5) x + cross join generate_series(1, 5) y; +-- currently, it is not possible to change the generated state of an +-- inheritance tree of depth >= 2 (same as in DROP EXPRESSION), so we expect an +-- error here. This might be fixed later. +begin; +alter table testgen.tpart alter column c + add generated always as (a + b) stored; +rollback; + +drop table testgen.tpart; + +-- tests for invalid invocations +alter table doesnotexist alter column foo + add generated always as (bar * 2) stored; + +create table testgen.t1 (a int); + +alter table testgen.t1 alter column doesnotexist + add generated always as (bar * 2) stored; + +alter table testgen.t1 add column b int; + +alter table testgen.t1 alter column b + add generated always as (doesnotexist * 2) stored; + +-- invalid: only supports ALWAYS +alter table testgen.t1 alter column b + add generated by default as (a * 2) stored; + +-- invalid: only supports STORED +alter table testgen.t1 alter column b add generated always as (a * 2); +alter table testgen.t1 alter column b add generated always as (a * 2) virtual; + +-- invalid: b is already a generated column +create table testgen.t2 (a int, b int generated always as (a * 2) stored); +alter table testgen.t2 alter column b add generated always as (a * 2) stored; +drop table testgen.t2; + +create table testgen.t3 (a int, b int); +-- invalid: expr must be immutable +alter table testgen.t3 alter column b + add generated always as (a + random()) stored; +-- invalid: expr cannot use subselects +alter table testgen.t3 alter column b + add generated always as (a + (select 1)) stored; +drop table testgen.t3; + +drop schema testgen cascade; base-commit: 6b48f5d1a74168c78badfb2e59ef788bb8eb396e -- 2.47.0 --zfrmj4necy5zy3mo Content-Type: text/plain; charset=utf-8 Content-Disposition: attachment; filename="v4-0002-Try-to-avoid-a-rewrite-when-adding-a-stored-gener.patch" ^ permalink raw reply [nested|flat] 559+ messages in thread
end of thread, other threads:[~2026-05-14 21:51 UTC | newest] Thread overview: 559+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2024-08-27 10:13 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2024-09-04 10:29 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2024-09-06 07:55 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2024-10-09 07:44 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2024-12-11 18:22 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-01-13 13:29 [PATCH 3/8] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-02-26 08:17 [PATCH 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-02-26 08:17 [PATCH v09 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-03-24 19:08 [PATCH v10 3/9] Move conversion of a "historic" to MVCC snapshot to a separate function. Álvaro Herrera <[email protected]> 2025-03-31 13:47 [PATCH 2/9] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-04-01 11:48 [PATCH 2/9] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-04-11 09:13 [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-09 10:00 [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH 2/7] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-06-30 17:41 [PATCH v17 2/3] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v19 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-08-11 13:23 [PATCH v20 4/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-04 17:20 [PATCH 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-09 18:44 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2025-12-13 18:27 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-08 16:47 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-12 16:30 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-22 08:23 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH v33 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-01-27 10:48 [PATCH 3/6] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-16 19:49 [PATCH v35 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-02-27 18:01 [PATCH 3/5] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]> 2026-05-14 21:51 [PATCH v4 1/2] Support changing a column into a stored generated column Alberto Piai <[email protected]>
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