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* [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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ messages in thread
* [PATCH v13 1/2] Key PGSTAT_KIND_RELATION by relfile locator
@ 2025-10-01 09:45 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 367+ messages in thread
From: Bertrand Drouvot @ 2025-10-01 09:45 UTC (permalink / raw)
This patch changes the key used for the PGSTAT_KIND_RELATION statistic kind.
Instead of the relation oid, it now relies on:
- dboid (linked to RelFileLocator's dbOid)
- objoid which is the result of a new macro (namely RelFileLocatorToPgStatObjid())
that computes an objoid based on the RelFileLocator's spcOid and the
RelFileLocator's relNumber.
This is possible as, since b14e9ce7d55c, the objoid is now uint64 and spcOid
and relNumber are 32 bits.
That will allow us to add new stats (add writes counters) and ensure that some
counters (n_dead_tup and friends) are replicated.
The patch introduces pgstat_reloid_to_relfilelocator() to 1) avoid calling
RelationIdGetRelation() to get the relfilelocator based on the relation oid
and 2) handle the partitioned table case.
Please note that:
- when running pg_stat_have_stats('relation',...) we now need to be connected
to the database that hosts the relation. As pg_stat_have_stats() is not
documented publicly, then the changes done in 029_stats_restart.pl look
enough.
- this patch does not handle rewrites so some tests are failing. It's only
intent is to ease the review and should not be pushed without being
merged with the following patch that handles the rewrites.
- it can be used to test that stats are incremented correctly and that we're
able to retrieve them as long as rewrites are not involved.
---
src/backend/postmaster/autovacuum.c | 17 +-
src/backend/utils/activity/pgstat_relation.c | 236 ++++++++++++++++---
src/backend/utils/adt/pgstatfuncs.c | 21 +-
src/include/catalog/pg_tablespace.dat | 4 +
src/include/catalog/pg_tablespace.h | 8 +
src/include/pgstat.h | 15 +-
src/include/utils/pgstat_internal.h | 1 +
src/test/recovery/t/029_stats_restart.pl | 40 ++--
8 files changed, 271 insertions(+), 71 deletions(-)
6.1% src/backend/postmaster/
61.7% src/backend/utils/activity/
4.9% src/backend/utils/adt/
3.2% src/include/catalog/
5.6% src/include/
18.1% src/test/recovery/t/
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 219673db930..4bef7ab7543 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -1992,12 +1992,16 @@ do_autovacuum(void)
bool dovacuum;
bool doanalyze;
bool wraparound;
+ RelFileLocator locator;
if (classForm->relkind != RELKIND_RELATION &&
classForm->relkind != RELKIND_MATVIEW)
continue;
relid = classForm->oid;
+ locator.dbOid = classForm->relisshared ? InvalidOid : MyDatabaseId;
+ locator.spcOid = classForm->reltablespace;
+ locator.relNumber = classForm->relfilenode;
/*
* Check if it is a temp table (presumably, of some other backend's).
@@ -2026,8 +2030,7 @@ do_autovacuum(void)
/* Fetch reloptions and the pgstat entry for this table */
relopts = extract_autovac_opts(tuple, pg_class_desc);
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_by_locator(locator);
/* Check if it needs vacuum or analyze */
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
@@ -2092,6 +2095,7 @@ do_autovacuum(void)
bool dovacuum;
bool doanalyze;
bool wraparound;
+ RelFileLocator locator;
/*
* We cannot safely process other backends' temp tables, so skip 'em.
@@ -2100,6 +2104,9 @@ do_autovacuum(void)
continue;
relid = classForm->oid;
+ locator.dbOid = classForm->relisshared ? InvalidOid : MyDatabaseId;
+ locator.spcOid = classForm->reltablespace;
+ locator.relNumber = classForm->relfilenode;
/*
* fetch reloptions -- if this toast table does not have them, try the
@@ -2119,8 +2126,7 @@ do_autovacuum(void)
}
/* Fetch the pgstat entry for this table */
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_by_locator(locator);
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
effective_multixact_freeze_max_age,
@@ -2917,8 +2923,7 @@ recheck_relation_needs_vacanalyze(Oid relid,
PgStat_StatTabEntry *tabentry;
/* fetch the pgstat table entry */
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_ext(relid);
relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
effective_multixact_freeze_max_age,
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index bc8c43b96aa..89bf0cbed56 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -17,12 +17,17 @@
#include "postgres.h"
+#include "access/htup_details.h"
#include "access/twophase_rmgr.h"
#include "access/xact.h"
#include "catalog/catalog.h"
+#include "catalog/pg_tablespace.h"
+#include "storage/lmgr.h"
#include "utils/memutils.h"
#include "utils/pgstat_internal.h"
#include "utils/rel.h"
+#include "utils/relmapper.h"
+#include "utils/syscache.h"
#include "utils/timestamp.h"
@@ -36,13 +41,12 @@ typedef struct TwoPhasePgStatRecord
PgStat_Counter inserted_pre_truncdrop;
PgStat_Counter updated_pre_truncdrop;
PgStat_Counter deleted_pre_truncdrop;
- Oid id; /* table's OID */
- bool shared; /* is it a shared catalog? */
+ RelFileLocator locator; /* table's rd_locator */
bool truncdropped; /* was the relation truncated/dropped? */
} TwoPhasePgStatRecord;
-static PgStat_TableStatus *pgstat_prep_relation_pending(Oid rel_id, bool isshared);
+static PgStat_TableStatus *pgstat_prep_relation_pending(RelFileLocator locator);
static void add_tabstat_xact_level(PgStat_TableStatus *pgstat_info, int nest_level);
static void ensure_tabstat_xact_level(PgStat_TableStatus *pgstat_info);
static void save_truncdrop_counters(PgStat_TableXactStatus *trans, bool is_drop);
@@ -60,8 +64,7 @@ pgstat_copy_relation_stats(Relation dst, Relation src)
PgStatShared_Relation *dstshstats;
PgStat_EntryRef *dst_ref;
- srcstats = pgstat_fetch_stat_tabentry_ext(src->rd_rel->relisshared,
- RelationGetRelid(src));
+ srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src));
if (!srcstats)
return;
@@ -94,8 +97,10 @@ pgstat_init_relation(Relation rel)
/*
* We only count stats for relations with storage and partitioned tables
+ * and we don't count stats generated during a rewrite.
*/
- if (!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE)
+ if ((!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE) ||
+ OidIsValid(rel->rd_rel->relrewrite))
{
rel->pgstat_enabled = false;
rel->pgstat_info = NULL;
@@ -130,12 +135,37 @@ pgstat_init_relation(Relation rel)
void
pgstat_assoc_relation(Relation rel)
{
+ RelFileLocator locator;
+
Assert(rel->pgstat_enabled);
Assert(rel->pgstat_info == NULL);
+ /*
+ * Don't associate stats for relations without storage and non partitioned
+ * tables.
+ */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind) &&
+ rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ return;
+
+ if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ locator = rel->rd_locator;
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+ locator.spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator.relNumber = rel->rd_id;
+ }
+
/* Else find or make the PgStat_TableStatus entry, and update link */
- rel->pgstat_info = pgstat_prep_relation_pending(RelationGetRelid(rel),
- rel->rd_rel->relisshared);
+ rel->pgstat_info = pgstat_prep_relation_pending(locator);
/* don't allow link a stats to multiple relcache entries */
Assert(rel->pgstat_info->relation == NULL);
@@ -167,9 +197,13 @@ pgstat_unlink_relation(Relation rel)
void
pgstat_create_relation(Relation rel)
{
+ /* don't track stats for relations without storage */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+ return;
+
pgstat_create_transactional(PGSTAT_KIND_RELATION,
- rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
- RelationGetRelid(rel));
+ rel->rd_locator.dbOid,
+ RelFileLocatorToPgStatObjid(rel->rd_locator));
}
/*
@@ -181,9 +215,13 @@ pgstat_drop_relation(Relation rel)
int nest_level = GetCurrentTransactionNestLevel();
PgStat_TableStatus *pgstat_info;
+ /* don't track stats for relations without storage */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+ return;
+
pgstat_drop_transactional(PGSTAT_KIND_RELATION,
- rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
- RelationGetRelid(rel));
+ rel->rd_locator.dbOid,
+ RelFileLocatorToPgStatObjid(rel->rd_locator));
if (!pgstat_should_count_relation(rel))
return;
@@ -213,20 +251,23 @@ pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples,
PgStat_EntryRef *entry_ref;
PgStatShared_Relation *shtabentry;
PgStat_StatTabEntry *tabentry;
- Oid dboid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
TimestampTz ts;
PgStat_Counter elapsedtime;
+ RelFileLocator locator;
if (!pgstat_track_counts)
return;
+ locator = rel->rd_locator;
+
/* Store the data in the table's hash table entry. */
ts = GetCurrentTimestamp();
elapsedtime = TimestampDifferenceMilliseconds(starttime, ts);
/* block acquiring lock for the same reason as pgstat_report_autovac() */
- entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, dboid,
- RelationGetRelid(rel), false);
+ entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator),
+ false);
shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
tabentry = &shtabentry->stats;
@@ -285,9 +326,9 @@ pgstat_report_analyze(Relation rel,
PgStat_EntryRef *entry_ref;
PgStatShared_Relation *shtabentry;
PgStat_StatTabEntry *tabentry;
- Oid dboid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
TimestampTz ts;
PgStat_Counter elapsedtime;
+ RelFileLocator locator;
if (!pgstat_track_counts)
return;
@@ -325,9 +366,25 @@ pgstat_report_analyze(Relation rel,
ts = GetCurrentTimestamp();
elapsedtime = TimestampDifferenceMilliseconds(starttime, ts);
+ if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ locator = rel->rd_locator;
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+ locator.spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator.relNumber = rel->rd_id;
+ }
/* block acquiring lock for the same reason as pgstat_report_autovac() */
- entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, dboid,
- RelationGetRelid(rel),
+ entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator),
false);
/* can't get dropped while accessed */
Assert(entry_ref != NULL && entry_ref->shared_stats != NULL);
@@ -468,7 +525,16 @@ pgstat_update_heap_dead_tuples(Relation rel, int delta)
PgStat_StatTabEntry *
pgstat_fetch_stat_tabentry(Oid relid)
{
- return pgstat_fetch_stat_tabentry_ext(IsSharedRelation(relid), relid);
+ return pgstat_fetch_stat_tabentry_ext(relid);
+}
+
+PgStat_StatTabEntry *
+pgstat_fetch_stat_tabentry_by_locator(RelFileLocator locator)
+{
+ return (PgStat_StatTabEntry *) pgstat_fetch_entry(
+ PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
}
/*
@@ -476,12 +542,14 @@ pgstat_fetch_stat_tabentry(Oid relid)
* whether the to-be-accessed table is a shared relation or not.
*/
PgStat_StatTabEntry *
-pgstat_fetch_stat_tabentry_ext(bool shared, Oid reloid)
+pgstat_fetch_stat_tabentry_ext(Oid reloid)
{
- Oid dboid = (shared ? InvalidOid : MyDatabaseId);
+ RelFileLocator locator;
- return (PgStat_StatTabEntry *)
- pgstat_fetch_entry(PGSTAT_KIND_RELATION, dboid, reloid);
+ if (!pgstat_reloid_to_relfilelocator(reloid, &locator))
+ return NULL;
+
+ return pgstat_fetch_stat_tabentry_by_locator(locator);
}
/*
@@ -503,14 +571,17 @@ find_tabstat_entry(Oid rel_id)
PgStat_TableXactStatus *trans;
PgStat_TableStatus *tabentry = NULL;
PgStat_TableStatus *tablestatus = NULL;
+ RelFileLocator locator;
+
+ if (!pgstat_reloid_to_relfilelocator(rel_id, &locator))
+ return NULL;
+
+ entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
- entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, MyDatabaseId, rel_id);
if (!entry_ref)
- {
- entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, InvalidOid, rel_id);
- if (!entry_ref)
- return tablestatus;
- }
+ return tablestatus;
tabentry = (PgStat_TableStatus *) entry_ref->pending;
tablestatus = palloc_object(PgStat_TableStatus);
@@ -706,8 +777,12 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
record.inserted_pre_truncdrop = trans->inserted_pre_truncdrop;
record.updated_pre_truncdrop = trans->updated_pre_truncdrop;
record.deleted_pre_truncdrop = trans->deleted_pre_truncdrop;
- record.id = tabstat->id;
- record.shared = tabstat->shared;
+
+ if (tabstat->relation != NULL)
+ record.locator = tabstat->relation->rd_locator;
+ else
+ record.locator = tabstat->locator;
+
record.truncdropped = trans->truncdropped;
RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
@@ -750,7 +825,7 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
PgStat_TableStatus *pgstat_info;
/* Find or create a tabstat entry for the rel */
- pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+ pgstat_info = pgstat_prep_relation_pending(rec->locator);
/* Same math as in AtEOXact_PgStat, commit case */
pgstat_info->counts.tuples_inserted += rec->tuples_inserted;
@@ -785,8 +860,8 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
PgStat_TableStatus *pgstat_info;
- /* Find or create a tabstat entry for the rel */
- pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+ /* Find or create a tabstat entry for the target locator */
+ pgstat_info = pgstat_prep_relation_pending(rec->locator);
/* Same math as in AtEOXact_PgStat, abort case */
if (rec->truncdropped)
@@ -920,17 +995,21 @@ pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
* initialized if not exists.
*/
static PgStat_TableStatus *
-pgstat_prep_relation_pending(Oid rel_id, bool isshared)
+pgstat_prep_relation_pending(RelFileLocator locator)
{
PgStat_EntryRef *entry_ref;
PgStat_TableStatus *pending;
+ uint64 objid;
+
+ objid = RelFileLocatorToPgStatObjid(locator);
entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_RELATION,
- isshared ? InvalidOid : MyDatabaseId,
- rel_id, NULL);
+ locator.dbOid,
+ objid, NULL);
+
pending = entry_ref->pending;
- pending->id = rel_id;
- pending->shared = isshared;
+ pending->id = objid;
+ pending->locator = locator;
return pending;
}
@@ -1009,3 +1088,82 @@ restore_truncdrop_counters(PgStat_TableXactStatus *trans)
trans->tuples_deleted = trans->deleted_pre_truncdrop;
}
}
+
+/*
+ * Convert a relation OID to its corresponding RelFileLocator for statistics
+ * tracking purposes.
+ *
+ * Returns true on success, false if the relation doesn't need statistics
+ * tracking.
+ *
+ * For partitioned tables, constructs a synthetic locator using the relation
+ * OID as relNumber, since they don't have storage.
+ */
+bool
+pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator)
+{
+ HeapTuple tuple;
+ Form_pg_class relform;
+ bool result = true;
+
+ /* get the relation's tuple from pg_class */
+ tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
+
+ if (!HeapTupleIsValid(tuple))
+ return false;
+
+ relform = (Form_pg_class) GETSTRUCT(tuple);
+
+ /* skip relations without storage and non partitioned tables */
+ if (!RELKIND_HAS_STORAGE(relform->relkind) &&
+ relform->relkind != RELKIND_PARTITIONED_TABLE)
+ {
+ ReleaseSysCache(tuple);
+ return false;
+ }
+
+ if (relform->relkind != RELKIND_PARTITIONED_TABLE)
+ {
+ /* build the RelFileLocator */
+ locator->relNumber = relform->relfilenode;
+ locator->spcOid = relform->reltablespace;
+
+ /* handle default tablespace */
+ if (!OidIsValid(locator->spcOid))
+ locator->spcOid = MyDatabaseTableSpace;
+
+ /* handle dbOid for global vs local relations */
+ if (locator->spcOid == GLOBALTABLESPACE_OID)
+ locator->dbOid = InvalidOid;
+ else
+ locator->dbOid = MyDatabaseId;
+
+ /* handle mapped relations */
+ if (!RelFileNumberIsValid(locator->relNumber))
+ {
+ locator->relNumber = RelationMapOidToFilenumber(reloid,
+ relform->relisshared);
+ if (!RelFileNumberIsValid(locator->relNumber))
+ {
+ ReleaseSysCache(tuple);
+ return false;
+ }
+ }
+ }
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator->dbOid = (relform->relisshared ? InvalidOid : MyDatabaseId);
+ locator->spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator->relNumber = relform->oid;
+ }
+
+ ReleaseSysCache(tuple);
+ return result;
+}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 5f907335990..106d1e577a7 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -30,6 +30,7 @@
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/builtins.h"
+#include "utils/pgstat_internal.h"
#include "utils/timestamp.h"
#include "utils/tuplestore.h"
#include "utils/wait_event.h"
@@ -1965,9 +1966,14 @@ Datum
pg_stat_reset_single_table_counters(PG_FUNCTION_ARGS)
{
Oid taboid = PG_GETARG_OID(0);
- Oid dboid = (IsSharedRelation(taboid) ? InvalidOid : MyDatabaseId);
+ RelFileLocator locator;
- pgstat_reset(PGSTAT_KIND_RELATION, dboid, taboid);
+ /* Get the stats locator from the relation OID */
+ if (!pgstat_reloid_to_relfilelocator(taboid, &locator))
+ PG_RETURN_VOID();
+
+ pgstat_reset(PGSTAT_KIND_RELATION, locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
PG_RETURN_VOID();
}
@@ -2324,5 +2330,16 @@ pg_stat_have_stats(PG_FUNCTION_ARGS)
uint64 objid = PG_GETARG_INT64(2);
PgStat_Kind kind = pgstat_get_kind_from_str(stats_type);
+ /* Convert relation OID to relfilenode objid */
+ if (kind == PGSTAT_KIND_RELATION)
+ {
+ RelFileLocator locator;
+
+ if (!pgstat_reloid_to_relfilelocator(objid, &locator))
+ PG_RETURN_BOOL(false);
+
+ objid = RelFileLocatorToPgStatObjid(locator);
+ }
+
PG_RETURN_BOOL(pgstat_have_entry(kind, dboid, objid));
}
diff --git a/src/include/catalog/pg_tablespace.dat b/src/include/catalog/pg_tablespace.dat
index c4cde415219..73ed046be31 100644
--- a/src/include/catalog/pg_tablespace.dat
+++ b/src/include/catalog/pg_tablespace.dat
@@ -10,6 +10,10 @@
#
#----------------------------------------------------------------------
+/*
+ * When adding a new one, ensure it does not conflict with
+ * PSEUDO_PARTITION_TABLE_SPCOID.
+ */
[
{ oid => '1663', oid_symbol => 'DEFAULTTABLESPACE_OID',
diff --git a/src/include/catalog/pg_tablespace.h b/src/include/catalog/pg_tablespace.h
index 3bd4a74f003..e5e818eb0c5 100644
--- a/src/include/catalog/pg_tablespace.h
+++ b/src/include/catalog/pg_tablespace.h
@@ -21,6 +21,14 @@
#include "catalog/genbki.h"
#include "catalog/pg_tablespace_d.h" /* IWYU pragma: export */
+/*
+ * Reserved tablespace OID for partitioned table pseudo locators.
+ * This is not an actual tablespace, just a reserved value to distinguish
+ * partitioned table statistics from regular table statistics. Ensures it does
+ * not conflict with the ones in pg_tablespace.dat.
+ */
+#define PSEUDO_PARTITION_TABLE_SPCOID 1665
+
/* ----------------
* pg_tablespace definition. cpp turns this into
* typedef struct FormData_pg_tablespace
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 216b93492ba..689c624f373 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -15,6 +15,7 @@
#include "portability/instr_time.h"
#include "postmaster/pgarch.h" /* for MAX_XFN_CHARS */
#include "replication/conflict.h"
+#include "storage/relfilelocator.h"
#include "utils/backend_progress.h" /* for backward compatibility */ /* IWYU pragma: export */
#include "utils/backend_status.h" /* for backward compatibility */ /* IWYU pragma: export */
#include "utils/pgstat_kind.h"
@@ -38,6 +39,12 @@ typedef struct RelationData *Relation;
/* Default directory to store temporary statistics data in */
#define PG_STAT_TMP_DIR "pg_stat_tmp"
+/*
+ * Build a pgstat key Objid based on a RelFileLocator.
+ */
+#define RelFileLocatorToPgStatObjid(locator) \
+ (((uint64) (locator).spcOid << 32) | (locator).relNumber)
+
/* Values for track_functions GUC variable --- order is significant! */
typedef enum TrackFunctionsLevel
{
@@ -178,11 +185,11 @@ typedef struct PgStat_TableCounts
*/
typedef struct PgStat_TableStatus
{
- Oid id; /* table's OID */
- bool shared; /* is it a shared catalog? */
+ uint64 id; /* hash of relfilelocator for stats key */
struct PgStat_TableXactStatus *trans; /* lowest subxact's counts */
PgStat_TableCounts counts; /* event counts to be sent */
Relation relation; /* rel that is using this entry */
+ RelFileLocator locator; /* table's relfilelocator */
} PgStat_TableStatus;
/* ----------
@@ -738,8 +745,8 @@ extern void pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
void *recdata, uint32 len);
extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
-extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(bool shared,
- Oid reloid);
+extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_by_locator(RelFileLocator locator);
+extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(Oid reloid);
extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 9b8fbae00ed..42f29496551 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -765,6 +765,7 @@ extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
extern void pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
+extern bool pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator);
/*
diff --git a/src/test/recovery/t/029_stats_restart.pl b/src/test/recovery/t/029_stats_restart.pl
index cdc427dbc78..4d00087dc6f 100644
--- a/src/test/recovery/t/029_stats_restart.pl
+++ b/src/test/recovery/t/029_stats_restart.pl
@@ -55,10 +55,10 @@ trigger_funcrel_stat();
# verify stats objects exist
$sect = "initial";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
# regular shutdown
@@ -79,10 +79,10 @@ copy($og_stats, $statsfile) or die "Copy failed: $!";
$node->start;
$sect = "copy";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
$node->stop('immediate');
@@ -96,10 +96,10 @@ $node->start;
# stats should have been discarded
$sect = "post immediate";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
# get rid of backup statsfile
@@ -110,10 +110,10 @@ unlink $statsfile or die "cannot unlink $statsfile $!";
trigger_funcrel_stat();
$sect = "post immediate, new";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
# regular shutdown
@@ -129,10 +129,10 @@ $node->start;
# no stats present due to invalid stats file
$sect = "invalid_overwrite";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
@@ -145,10 +145,10 @@ append_file($og_stats, "XYZ");
$node->start;
$sect = "invalid_append";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
@@ -307,9 +307,9 @@ sub trigger_funcrel_stat
sub have_stats
{
- my ($kind, $dboid, $objid) = @_;
+ my ($db, $kind, $dboid, $objid) = @_;
- return $node->safe_psql($connect_db,
+ return $node->safe_psql($db,
"SELECT pg_stat_have_stats('$kind', $dboid, $objid)");
}
--
2.34.1
--USlF2Vr25us5UpvY
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v13-0002-handle-relation-statistics-correctly-during-rewr.patch"
^ permalink raw reply [nested|flat] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ 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; 367+ 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] 367+ messages in thread
end of thread, other threads:[~2026-02-27 18:01 UTC | newest]
Thread overview: 367+ 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 v09 3/9] 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]>
2025-03-24 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 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]>
2025-08-11 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 v25 3/4] Move conversion of a "historic" to MVCC snapshot to a separate function. Antonin Houska <[email protected]>
2025-10-01 09:45 [PATCH v13 1/2] Key PGSTAT_KIND_RELATION by relfile locator Bertrand Drouvot <[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]>
2025-12-13 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]>
2026-01-12 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]>
2026-01-27 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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]>
2026-02-27 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]>
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