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* Add regression test checking combinations of (object,backend_type,context) in pg_stat_io
@ 2025-03-05 02:05 Michael Paquier <[email protected]>
2025-03-05 07:34 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Bertrand Drouvot <[email protected]>
0 siblings, 1 reply; 36+ messages in thread
From: Michael Paquier @ 2025-03-05 02:05 UTC (permalink / raw)
To: Postgres hackers <[email protected]>
Hi all,
While working on I/O statistics, I have noticed that it is not
complicated to break the set of rows returned by pg_stat_io if one is
not careful when updating pgstat_tracks_io_object().
Attached is a patch that I've found useful as a sanity check,
returning all the combinations supported for BackendType, IOContext
and IOObject, so as it is easily possible to evaluate if the
information returned is relevant.
Thoughts?
--
Michael
Attachments:
[text/x-diff] statio-regress-check.patch (3.2K, ../../[email protected]/2-statio-regress-check.patch)
download | inline diff:
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 093e6368dbbe..8a28bc0ed623 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -11,6 +11,83 @@ SHOW track_counts; -- must be on
on
(1 row)
+-- List of backend types, context and objects tracked in pg_stat_io.
+\a
+SELECT backend_type, object, context FROM pg_stat_io ORDER BY 1, 2, 3;
+backend_type|object|context
+autovacuum launcher|relation|bulkread
+autovacuum launcher|relation|init
+autovacuum launcher|relation|normal
+autovacuum launcher|wal|init
+autovacuum launcher|wal|normal
+autovacuum worker|relation|bulkread
+autovacuum worker|relation|init
+autovacuum worker|relation|normal
+autovacuum worker|relation|vacuum
+autovacuum worker|wal|init
+autovacuum worker|wal|normal
+background worker|relation|bulkread
+background worker|relation|bulkwrite
+background worker|relation|init
+background worker|relation|normal
+background worker|relation|vacuum
+background worker|temp relation|normal
+background worker|wal|init
+background worker|wal|normal
+background writer|relation|init
+background writer|relation|normal
+background writer|wal|init
+background writer|wal|normal
+checkpointer|relation|init
+checkpointer|relation|normal
+checkpointer|wal|init
+checkpointer|wal|normal
+client backend|relation|bulkread
+client backend|relation|bulkwrite
+client backend|relation|init
+client backend|relation|normal
+client backend|relation|vacuum
+client backend|temp relation|normal
+client backend|wal|init
+client backend|wal|normal
+slotsync worker|relation|bulkread
+slotsync worker|relation|bulkwrite
+slotsync worker|relation|init
+slotsync worker|relation|normal
+slotsync worker|relation|vacuum
+slotsync worker|temp relation|normal
+slotsync worker|wal|init
+slotsync worker|wal|normal
+standalone backend|relation|bulkread
+standalone backend|relation|bulkwrite
+standalone backend|relation|init
+standalone backend|relation|normal
+standalone backend|relation|vacuum
+standalone backend|wal|init
+standalone backend|wal|normal
+startup|relation|bulkread
+startup|relation|bulkwrite
+startup|relation|init
+startup|relation|normal
+startup|relation|vacuum
+startup|wal|init
+startup|wal|normal
+walreceiver|wal|init
+walreceiver|wal|normal
+walsender|relation|bulkread
+walsender|relation|bulkwrite
+walsender|relation|init
+walsender|relation|normal
+walsender|relation|vacuum
+walsender|temp relation|normal
+walsender|wal|init
+walsender|wal|normal
+walsummarizer|wal|init
+walsummarizer|wal|normal
+walwriter|wal|init
+walwriter|wal|normal
+(71 rows)
+\a
-- ensure that both seqscan and indexscan plans are allowed
SET enable_seqscan TO on;
SET enable_indexscan TO on;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 0a44e14d9f4a..141e2073e8cb 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -8,6 +8,11 @@
-- conditio sine qua non
SHOW track_counts; -- must be on
+-- List of backend types, context and objects tracked in pg_stat_io.
+\a
+SELECT backend_type, object, context FROM pg_stat_io ORDER BY 1, 2, 3;
+\a
+
-- ensure that both seqscan and indexscan plans are allowed
SET enable_seqscan TO on;
SET enable_indexscan TO on;
[application/pgp-signature] signature.asc (833B, ../../[email protected]/3-signature.asc)
download
^ permalink raw reply [nested|flat] 36+ messages in thread
* Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io
2025-03-05 02:05 Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
@ 2025-03-05 07:34 ` Bertrand Drouvot <[email protected]>
2025-03-05 12:19 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
0 siblings, 1 reply; 36+ messages in thread
From: Bertrand Drouvot @ 2025-03-05 07:34 UTC (permalink / raw)
To: Michael Paquier <[email protected]>; +Cc: Postgres hackers <[email protected]>
Hi,
On Wed, Mar 05, 2025 at 11:05:48AM +0900, Michael Paquier wrote:
> Hi all,
>
> While working on I/O statistics, I have noticed that it is not
> complicated to break the set of rows returned by pg_stat_io if one is
> not careful when updating pgstat_tracks_io_object().
>
> Attached is a patch that I've found useful as a sanity check,
> returning all the combinations supported for BackendType, IOContext
> and IOObject, so as it is easily possible to evaluate if the
> information returned is relevant.
>
> Thoughts?
That would mean changing the test each time pgstat_tracks_io_object() is
modified in such a way that the output is changed. That's a good thing as
the writer will need to double check if the new output makes sense according
to his changes. So I don't see any reason not to add this test.
+SELECT backend_type, object, context FROM pg_stat_io ORDER BY 1, 2, 3;
What about adding some extra paranoia like?
SELECT backend_type, object, context FROM pg_stat_io ORDER BY backend_type, object, context COLLATE "C";
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
^ permalink raw reply [nested|flat] 36+ messages in thread
* Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io
2025-03-05 02:05 Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
2025-03-05 07:34 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Bertrand Drouvot <[email protected]>
@ 2025-03-05 12:19 ` Michael Paquier <[email protected]>
2025-03-09 22:55 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
0 siblings, 1 reply; 36+ messages in thread
From: Michael Paquier @ 2025-03-05 12:19 UTC (permalink / raw)
To: Bertrand Drouvot <[email protected]>; +Cc: Postgres hackers <[email protected]>
On Wed, Mar 05, 2025 at 07:34:16AM +0000, Bertrand Drouvot wrote:
> That would mean changing the test each time pgstat_tracks_io_object() is
> modified in such a way that the output is changed. That's a good thing as
> the writer will need to double check if the new output makes sense according
> to his changes. So I don't see any reason not to add this test.
Thanks for the review.
> What about adding some extra paranoia like?
>
> SELECT backend_type, object, context FROM pg_stat_io ORDER BY
> backend_type, object, context COLLATE "C";
Why not, to force the ordering.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, ../../[email protected]/2-signature.asc)
download
^ permalink raw reply [nested|flat] 36+ messages in thread
* Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io
2025-03-05 02:05 Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
2025-03-05 07:34 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Bertrand Drouvot <[email protected]>
2025-03-05 12:19 ` Re: Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
@ 2025-03-09 22:55 ` Michael Paquier <[email protected]>
0 siblings, 0 replies; 36+ messages in thread
From: Michael Paquier @ 2025-03-09 22:55 UTC (permalink / raw)
To: Bertrand Drouvot <[email protected]>; +Cc: Postgres hackers <[email protected]>
On Wed, Mar 05, 2025 at 09:19:16PM +0900, Michael Paquier wrote:
> On Wed, Mar 05, 2025 at 07:34:16AM +0000, Bertrand Drouvot wrote:
>> What about adding some extra paranoia like?
>>
>> SELECT backend_type, object, context FROM pg_stat_io ORDER BY
>> backend_type, object, context COLLATE "C";
>
> Why not, to force the ordering.
For the sake of the archives. As 8b532771a099 has proved, this has
required two more COLLATE clauses in the query to force a stable
output, but we are in the clear now.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, ../../[email protected]/2-signature.asc)
download
^ permalink raw reply [nested|flat] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ 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; 36+ 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] 36+ messages in thread
end of thread, other threads:[~2026-02-27 18:01 UTC | newest]
Thread overview: 36+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2025-03-05 02:05 Add regression test checking combinations of (object,backend_type,context) in pg_stat_io Michael Paquier <[email protected]>
2025-03-05 07:34 ` Bertrand Drouvot <[email protected]>
2025-03-05 12:19 ` Michael Paquier <[email protected]>
2025-03-09 22:55 ` Michael Paquier <[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 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 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]>
2025-12-04 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]>
2025-12-13 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]>
2026-01-12 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]>
2026-01-27 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]>
2026-02-16 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]>
2026-02-27 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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