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help / color / mirror / Atom feedFrom: Masahiko Sawada <[email protected]>
To: [email protected] <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: Drouvot, Bertrand <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Oh, Mike <[email protected]>
Subject: Re: [BUG] Logical replication failure "ERROR: could not map filenode "base/13237/442428" to relation OID" with catalog modifying txns
Date: Sun, 17 Jul 2022 21:58:36 +0900
Message-ID: <CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com> (raw)
In-Reply-To: <OSZPR01MB63106E9CE179D80F46CB3154FD8B9@OSZPR01MB6310.jpnprd01.prod.outlook.com>
References: <[email protected]>
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<CAD21AoAn9T6mS8sMF5=tFV66Wru92s933ihRVunLPEU_+0=Xiw@mail.gmail.com>
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On Fri, Jul 15, 2022 at 3:32 PM [email protected]
<[email protected]> wrote:
>
> On Mon, Jul 11, 2022 9:54 PM Masahiko Sawada <[email protected]> wrote:
> >
> > I've attached an updated patch, please review it.
> >
>
> Thanks for your patch. Here are some comments for the REL14-v1 patch.
>
> 1.
> + Size sz = sizeof(TransactionId) * nxacts;;
>
> There is a redundant semicolon at the end.
>
> 2.
> + workspace = MemoryContextAlloc(rb->context, rb->n_initial_running_xacts);
>
> Should it be:
> + workspace = MemoryContextAlloc(rb->context, sizeof(TransactionId) * rb->n_initial_running_xacts);
>
> 3.
> + /* bound check if there is at least one transaction to be removed */
> + if (NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
> + running->oldestRunningXid))
> + return;
> +
>
> Here, I think it should return if rb->initial_running_xacts[0] is older than
> oldestRunningXid, right? Should it be changed to:
>
> + if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
> + running->oldestRunningXid))
> + return;
>
> 4.
> + if ((parsed->xinfo & XACT_XINFO_HAS_INVALS) != 0)
>
> Maybe we can change it like the following, to be consistent with other places in
> this file. It's also fine if you don't change it.
>
> + if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
Thank you for the comments!
I've attached patches for all supported branches including the master.
Regards,
--
Masahiko Sawada
EDB: https://www.enterprisedb.com/
Attachments:
[application/octet-stream] REL13-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch (15.2K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/2-REL13-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch)
download | inline diff:
From 02e669a57d782b4488860ace7167bcff09af397f Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Mon, 11 Jul 2022 21:49:06 +0900
Subject: [PATCH v6] Fix catalog lookup with the wrong snapshot during logical
decoding.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change the reorder buffer so that it
remembers the initial running transaction written in the
xl_running_xacts record that we decoded first, and mark the
transaction as containing catalog changes if it’s in the list of the
initial running transactions and its commit record has
XACT_XINFO_HAS_INVALS.
This has false positive; we could end up adding the transaction that
didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the
COMMIT record. It doesn’t have the information on which (sub)
transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't
necessarily indicate that the transaction has catalog change. But it
doesn't become a problem since we use historic snapshot only for
reading system catalogs.
On the master branch, we took a more future-proof approach of writing
catalog modifying transactions to the serialized snapshot. But we
cannot backpatch it because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 44 +++++++
.../specs/catalog_change_snapshot.spec | 39 ++++++
src/backend/replication/logical/decode.c | 17 +++
.../replication/logical/reorderbuffer.c | 116 ++++++++++++++++++
src/include/replication/reorderbuffer.h | 36 ++++++
6 files changed, 253 insertions(+), 1 deletion(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index f439c582a5..6ec09ab192 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -7,7 +7,7 @@ REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
decoding_into_rel binary prepared replorigin time messages \
spill slot truncate
ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
- oldest_xmin snapshot_transfer subxact_without_top
+ oldest_xmin snapshot_transfer subxact_without_top catalog_change_snapshot
REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..dc4f9b7018
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,44 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+---------------------------------------
+BEGIN
+table public.tbl1: TRUNCATE: (no-flags)
+COMMIT
+(3 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..662760fbcf
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACT record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the XACT_RUNNING record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACT
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 5a2b828aa3..e2fa5ae6b5 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -316,6 +316,9 @@ DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
xl_running_xacts *running = (xl_running_xacts *) XLogRecGetData(r);
+ /* Process the initial running transactions, if any */
+ ReorderBufferProcessInitialXacts(ctx->reorder, running);
+
SnapBuildProcessRunningXacts(builder, buf->origptr, running);
/*
@@ -572,6 +575,20 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
commit_time = parsed->origin_timestamp;
}
+ /*
+ * If the COMMIT record has invalidation messages, it could have catalog
+ * changes. We check if it's in the list of the initial running transactions
+ * and then mark it as containing catalog change.
+ *
+ * This must be done before SnapBuildCommitTxn() so that we can include
+ * catalog change transactions to the historic snapshot.
+ */
+ if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
+ ReorderBufferInitialXactsSetCatalogChanges(ctx->reorder, xid,
+ parsed->nsubxacts,
+ parsed->subxacts,
+ buf->origptr);
+
/*
* Process invalidation messages, even if we're not interested in the
* transaction's contents, since the various caches need to always be
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index ef8c2ea6df..e6905d9264 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -318,6 +318,9 @@ ReorderBufferAllocate(void)
buffer->outbufsize = 0;
buffer->size = 0;
+ buffer->initial_running_xacts = NULL;
+ buffer->n_initial_running_xacts = 0;
+
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
@@ -3859,3 +3862,116 @@ restart:
*cmax = ent->cmax;
return true;
}
+
+/*
+ * Process the transactions in xl_running_xacts record, and remember the
+ * transactions first and later remove those that aren't needed anymore.
+ *
+ * We can ideally remove the transactions from the initial running xacts array
+ * once it is finished (committed/aborted) but that could be costly as we need
+ * to maintain the xids order in the array.
+ */
+void
+ReorderBufferProcessInitialXacts(ReorderBuffer *rb, xl_running_xacts *running)
+{
+ LogicalDecodingContext *ctx = rb->private_data;
+ SnapBuild *builder = ctx->snapshot_builder;
+ TransactionId *workspace;
+ int surviving_xids = 0;
+
+ /* Build the initial running transactions list for the first call */
+ if (unlikely(SnapBuildCurrentState(builder) == SNAPBUILD_START))
+ {
+ int nxacts = running->subxcnt + running->xcnt;
+ Size sz = sizeof(TransactionId) * nxacts;
+
+ Assert(rb->n_initial_running_xacts == 0);
+
+ rb->n_initial_running_xacts = nxacts;
+ rb->initial_running_xacts = MemoryContextAlloc(rb->context, sz);
+ memcpy(rb->initial_running_xacts, running->xids, sz);
+ qsort(rb->initial_running_xacts, nxacts, sizeof(TransactionId),
+ xidComparator);
+
+ return;
+ }
+
+ /* Quick exit if there is no initial running transactions */
+ if (likely(rb->n_initial_running_xacts == 0))
+ return;
+
+ /* bound check if there is at least one transaction to remove */
+ if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
+ running->oldestRunningXid))
+ return;
+
+ /*
+ * Remove transactions that would have been processed and we don't need to
+ * keep track off anymore.
+ *
+ * The purged array must also be sorted in xidComparator order.
+ */
+ workspace = MemoryContextAlloc(rb->context,
+ rb->n_initial_running_xacts * sizeof(TransactionId));
+ for (int i = 0; i < rb->n_initial_running_xacts; i++)
+ {
+ if (NormalTransactionIdPrecedes(rb->initial_running_xacts[i],
+ running->oldestRunningXid))
+ ; /* remove */
+ else
+ workspace[surviving_xids++] = rb->initial_running_xacts[i];
+ }
+
+ if (surviving_xids > 0)
+ memcpy(rb->initial_running_xacts, workspace,
+ sizeof(TransactionId) * surviving_xids);
+ else
+ {
+ pfree(rb->initial_running_xacts);
+ rb->initial_running_xacts = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, oldest running xid %u",
+ (uint32) rb->n_initial_running_xacts,
+ (uint32) surviving_xids,
+ running->oldestRunningXid);
+
+ rb->n_initial_running_xacts = surviving_xids;
+ pfree(workspace);
+}
+
+/*
+ * If the given xid is in the list of the initial running xacts, we mark both it
+ * and its subtransactions as containing catalog changes if not yet.
+ */
+void
+ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt, TransactionId *subxacts,
+ XLogRecPtr lsn)
+{
+ /*
+ * Skip if there is no initial running xacts information or the
+ * transaction is already marked as containing catalog changes.
+ */
+ if (likely(rb->n_initial_running_xacts == 0 ||
+ ReorderBufferXidHasCatalogChanges(rb, xid)))
+ return;
+
+ /*
+ * If this committed transaction is the one that was running at the time
+ * when decoding the first RUNNING_XACTS record and have done catalog
+ * changes, we can mark both the top transaction and its subtransactions
+ * as containing catalog changes.
+ */
+ if (bsearch(&xid, rb->initial_running_xacts, rb->n_initial_running_xacts,
+ sizeof(TransactionId), xidComparator) != NULL)
+ {
+ ReorderBufferXidSetCatalogChanges(rb, xid, lsn);
+
+ for (int i = 0; i < subxcnt; i++)
+ {
+ ReorderBufferAssignChild(rb, xid, subxacts[i], lsn);
+ ReorderBufferXidSetCatalogChanges(rb, subxacts[i], lsn);
+ }
+ }
+}
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 5347597e92..d90640ead8 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -12,6 +12,7 @@
#include "access/htup_details.h"
#include "lib/ilist.h"
#include "storage/sinval.h"
+#include "storage/standby.h"
#include "utils/hsearch.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
@@ -408,6 +409,35 @@ struct ReorderBuffer
XLogRecPtr current_restart_decoding_lsn;
+ /*
+ * Array of transactions and subtransactions that were running when
+ * the xl_running_xacts record that we decoded first was written.
+ * The array is sorted in xidComparator order. Xids are removed from
+ * the array when decoding xl_running_xacts record, and then the array
+ * eventually becomes an empty.
+ *
+ * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
+ * if the transaction has changed the catalog, and that information
+ * is not serialized to SnapBuilder. Therefore, if the logical
+ * decoding decodes the commit record of the transaction that actually
+ * has done catalog changes without these records, we miss to add
+ * the xid to the snapshot, and end up looking at catalogs with the
+ * wrong snapshot. To avoid this problem, if the COMMIT record of
+ * the xid listed in initial_running_xacts has XACT_XINFO_HAS_INVALS
+ * flag, we mark both the top transaction and its substransactions
+ * as containing catalog changes.
+ *
+ * We could end up adding the transaction that didn't change catalog
+ * to the snapshot since we cannot distinguish whether the transaction
+ * has catalog changes only by checking the COMMIT record. It doesn't
+ * have the information on which (sub) transaction has catalog changes,
+ * and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the
+ * transaction has catalog change. But it doesn't become a problem since
+ * we use historic snapshot only for reading system catalogs.
+ */
+ TransactionId *initial_running_xacts;
+ int n_initial_running_xacts;
+
/* buffer for disk<->memory conversions */
char *outbuf;
Size outbufsize;
@@ -465,4 +495,10 @@ void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
void StartupReorderBuffer(void);
+void ReorderBufferProcessInitialXacts(ReorderBuffer *rb,
+ xl_running_xacts *running);
+void ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt,
+ TransactionId *subxacts,
+ XLogRecPtr lsn);
#endif
--
2.24.3 (Apple Git-128)
[application/octet-stream] REL12-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch (15.2K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/3-REL12-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch)
download | inline diff:
From ef780b39be74ca91ed94031451a823268c1e05ee Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Sun, 17 Jul 2022 07:19:00 +0900
Subject: [PATCH v6] Fix catalog lookup with the wrong snapshot during logical
decoding.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change the reorder buffer so that it
remembers the initial running transaction written in the
xl_running_xacts record that we decoded first, and mark the
transaction as containing catalog changes if it’s in the list of the
initial running transactions and its commit record has
XACT_XINFO_HAS_INVALS.
This has false positive; we could end up adding the transaction that
didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the
COMMIT record. It doesn’t have the information on which (sub)
transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't
necessarily indicate that the transaction has catalog change. But it
doesn't become a problem since we use historic snapshot only for
reading system catalogs.
On the master branch, we took a more future-proof approach of writing
catalog modifying transactions to the serialized snapshot. But we
cannot backpatch it because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 44 +++++++
.../specs/catalog_change_snapshot.spec | 39 ++++++
src/backend/replication/logical/decode.c | 17 +++
.../replication/logical/reorderbuffer.c | 116 ++++++++++++++++++
src/include/replication/reorderbuffer.h | 36 ++++++
6 files changed, 253 insertions(+), 1 deletion(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index f439c582a5..6ec09ab192 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -7,7 +7,7 @@ REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
decoding_into_rel binary prepared replorigin time messages \
spill slot truncate
ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
- oldest_xmin snapshot_transfer subxact_without_top
+ oldest_xmin snapshot_transfer subxact_without_top catalog_change_snapshot
REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..dc4f9b7018
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,44 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+---------------------------------------
+BEGIN
+table public.tbl1: TRUNCATE: (no-flags)
+COMMIT
+(3 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..662760fbcf
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACT record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the XACT_RUNNING record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACT
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 60d07ce4eb..94983644a1 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -319,6 +319,9 @@ DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
xl_running_xacts *running = (xl_running_xacts *) XLogRecGetData(r);
+ /* Process the initial running transactions, if any */
+ ReorderBufferProcessInitialXacts(ctx->reorder, running);
+
SnapBuildProcessRunningXacts(builder, buf->origptr, running);
/*
@@ -575,6 +578,20 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
commit_time = parsed->origin_timestamp;
}
+ /*
+ * If the COMMIT record has invalidation messages, it could have catalog
+ * changes. We check if it's in the list of the initial running transactions
+ * and then mark it as containing catalog change.
+ *
+ * This must be done before SnapBuildCommitTxn() so that we can include
+ * catalog change transactions to the historic snapshot.
+ */
+ if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
+ ReorderBufferInitialXactsSetCatalogChanges(ctx->reorder, xid,
+ parsed->nsubxacts,
+ parsed->subxacts,
+ buf->origptr);
+
/*
* Process invalidation messages, even if we're not interested in the
* transaction's contents, since the various caches need to always be
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 475f76fa5e..314111dcd2 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -279,6 +279,9 @@ ReorderBufferAllocate(void)
buffer->outbuf = NULL;
buffer->outbufsize = 0;
+ buffer->initial_running_xacts = NULL;
+ buffer->n_initial_running_xacts = 0;
+
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
@@ -3593,3 +3596,116 @@ restart:
*cmax = ent->cmax;
return true;
}
+
+/*
+ * Process the transactions in xl_running_xacts record, and remember the
+ * transactions first and later remove those that aren't needed anymore.
+ *
+ * We can ideally remove the transactions from the initial running xacts array
+ * once it is finished (committed/aborted) but that could be costly as we need
+ * to maintain the xids order in the array.
+ */
+void
+ReorderBufferProcessInitialXacts(ReorderBuffer *rb, xl_running_xacts *running)
+{
+ LogicalDecodingContext *ctx = rb->private_data;
+ SnapBuild *builder = ctx->snapshot_builder;
+ TransactionId *workspace;
+ int surviving_xids = 0;
+
+ /* Build the initial running transactions list for the first call */
+ if (unlikely(SnapBuildCurrentState(builder) == SNAPBUILD_START))
+ {
+ int nxacts = running->subxcnt + running->xcnt;
+ Size sz = sizeof(TransactionId) * nxacts;
+
+ Assert(rb->n_initial_running_xacts == 0);
+
+ rb->n_initial_running_xacts = nxacts;
+ rb->initial_running_xacts = MemoryContextAlloc(rb->context, sz);
+ memcpy(rb->initial_running_xacts, running->xids, sz);
+ qsort(rb->initial_running_xacts, nxacts, sizeof(TransactionId),
+ xidComparator);
+
+ return;
+ }
+
+ /* Quick exit if there is no initial running transactions */
+ if (likely(rb->n_initial_running_xacts == 0))
+ return;
+
+ /* bound check if there is at least one transaction to remove */
+ if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
+ running->oldestRunningXid))
+ return;
+
+ /*
+ * Remove transactions that would have been processed and we don't need to
+ * keep track off anymore.
+ *
+ * The purged array must also be sorted in xidComparator order.
+ */
+ workspace = MemoryContextAlloc(rb->context,
+ rb->n_initial_running_xacts * sizeof(TransactionId));
+ for (int i = 0; i < rb->n_initial_running_xacts; i++)
+ {
+ if (NormalTransactionIdPrecedes(rb->initial_running_xacts[i],
+ running->oldestRunningXid))
+ ; /* remove */
+ else
+ workspace[surviving_xids++] = rb->initial_running_xacts[i];
+ }
+
+ if (surviving_xids > 0)
+ memcpy(rb->initial_running_xacts, workspace,
+ sizeof(TransactionId) * surviving_xids);
+ else
+ {
+ pfree(rb->initial_running_xacts);
+ rb->initial_running_xacts = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, oldest running xid %u",
+ (uint32) rb->n_initial_running_xacts,
+ (uint32) surviving_xids,
+ running->oldestRunningXid);
+
+ rb->n_initial_running_xacts = surviving_xids;
+ pfree(workspace);
+}
+
+/*
+ * If the given xid is in the list of the initial running xacts, we mark both it
+ * and its subtransactions as containing catalog changes if not yet.
+ */
+void
+ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt, TransactionId *subxacts,
+ XLogRecPtr lsn)
+{
+ /*
+ * Skip if there is no initial running xacts information or the
+ * transaction is already marked as containing catalog changes.
+ */
+ if (likely(rb->n_initial_running_xacts == 0 ||
+ ReorderBufferXidHasCatalogChanges(rb, xid)))
+ return;
+
+ /*
+ * If this committed transaction is the one that was running at the time
+ * when decoding the first RUNNING_XACTS record and have done catalog
+ * changes, we can mark both the top transaction and its subtransactions
+ * as containing catalog changes.
+ */
+ if (bsearch(&xid, rb->initial_running_xacts, rb->n_initial_running_xacts,
+ sizeof(TransactionId), xidComparator) != NULL)
+ {
+ ReorderBufferXidSetCatalogChanges(rb, xid, lsn);
+
+ for (int i = 0; i < subxcnt; i++)
+ {
+ ReorderBufferAssignChild(rb, xid, subxacts[i], lsn);
+ ReorderBufferXidSetCatalogChanges(rb, subxacts[i], lsn);
+ }
+ }
+}
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index bc97b08a90..d6466a4e20 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -12,6 +12,7 @@
#include "access/htup_details.h"
#include "lib/ilist.h"
#include "storage/sinval.h"
+#include "storage/standby.h"
#include "utils/hsearch.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
@@ -385,6 +386,35 @@ struct ReorderBuffer
XLogRecPtr current_restart_decoding_lsn;
+ /*
+ * Array of transactions and subtransactions that were running when
+ * the xl_running_xacts record that we decoded first was written.
+ * The array is sorted in xidComparator order. Xids are removed from
+ * the array when decoding xl_running_xacts record, and then the array
+ * eventually becomes an empty.
+ *
+ * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
+ * if the transaction has changed the catalog, and that information
+ * is not serialized to SnapBuilder. Therefore, if the logical
+ * decoding decodes the commit record of the transaction that actually
+ * has done catalog changes without these records, we miss to add
+ * the xid to the snapshot, and end up looking at catalogs with the
+ * wrong snapshot. To avoid this problem, if the COMMIT record of
+ * the xid listed in initial_running_xacts has XACT_XINFO_HAS_INVALS
+ * flag, we mark both the top transaction and its substransactions
+ * as containing catalog changes.
+ *
+ * We could end up adding the transaction that didn't change catalog
+ * to the snapshot since we cannot distinguish whether the transaction
+ * has catalog changes only by checking the COMMIT record. It doesn't
+ * have the information on which (sub) transaction has catalog changes,
+ * and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the
+ * transaction has catalog change. But it doesn't become a problem since
+ * we use historic snapshot only for reading system catalogs.
+ */
+ TransactionId *initial_running_xacts;
+ int n_initial_running_xacts;
+
/* buffer for disk<->memory conversions */
char *outbuf;
Size outbufsize;
@@ -439,4 +469,10 @@ void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
void StartupReorderBuffer(void);
+void ReorderBufferProcessInitialXacts(ReorderBuffer *rb,
+ xl_running_xacts *running);
+void ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt,
+ TransactionId *subxacts,
+ XLogRecPtr lsn);
#endif
--
2.24.3 (Apple Git-128)
[application/octet-stream] REL14-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch (15.1K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/4-REL14-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch)
download | inline diff:
From 7fddf151b27e185cf27ae0f6d1a965a0b928c22a Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Mon, 11 Jul 2022 21:49:06 +0900
Subject: [PATCH v6] Fix catalog lookup with the wrong snapshot during logical
decoding.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change the reorder buffer so that it
remembers the initial running transaction written in the
xl_running_xacts record that we decoded first, and mark the
transaction as containing catalog changes if it’s in the list of the
initial running transactions and its commit record has
XACT_XINFO_HAS_INVALS.
This has false positive; we could end up adding the transaction that
didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the
COMMIT record. It doesn’t have the information on which (sub)
transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't
necessarily indicate that the transaction has catalog change. But it
doesn't become a problem since we use historic snapshot only for
reading system catalogs.
On the master branch, we took a more future-proof approach of writing
catalog modifying transactions to the serialized snapshot. But we
cannot backpatch it because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 44 +++++++
.../specs/catalog_change_snapshot.spec | 39 ++++++
src/backend/replication/logical/decode.c | 17 +++
.../replication/logical/reorderbuffer.c | 116 ++++++++++++++++++
src/include/replication/reorderbuffer.h | 36 ++++++
6 files changed, 253 insertions(+), 1 deletion(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index 9a31e0b879..4553252d75 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -8,7 +8,7 @@ REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
spill slot truncate stream stats twophase twophase_stream
ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
oldest_xmin snapshot_transfer subxact_without_top concurrent_stream \
- twophase_snapshot
+ twophase_snapshot catalog_change_snapshot
REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..dc4f9b7018
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,44 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+---------------------------------------
+BEGIN
+table public.tbl1: TRUNCATE: (no-flags)
+COMMIT
+(3 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..662760fbcf
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACT record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the XACT_RUNNING record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACT
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 92dfafc632..8d72c5af1f 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -407,6 +407,9 @@ DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
xl_running_xacts *running = (xl_running_xacts *) XLogRecGetData(r);
+ /* Process the initial running transactions, if any */
+ ReorderBufferProcessInitialXacts(ctx->reorder, running);
+
SnapBuildProcessRunningXacts(builder, buf->origptr, running);
/*
@@ -691,6 +694,20 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
commit_time = parsed->origin_timestamp;
}
+ /*
+ * If the COMMIT record has invalidation messages, it could have catalog
+ * changes. We check if it's in the list of the initial running transactions
+ * and then mark it as containing catalog change.
+ *
+ * This must be done before SnapBuildCommitTxn() so that we can include
+ * catalog change transactions to the historic snapshot.
+ */
+ if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
+ ReorderBufferInitialXactsSetCatalogChanges(ctx->reorder, xid,
+ parsed->nsubxacts,
+ parsed->subxacts,
+ buf->origptr);
+
SnapBuildCommitTxn(ctx->snapshot_builder, buf->origptr, xid,
parsed->nsubxacts, parsed->subxacts);
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index e59d1396b5..bef9fb9bb2 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -346,6 +346,9 @@ ReorderBufferAllocate(void)
buffer->outbufsize = 0;
buffer->size = 0;
+ buffer->initial_running_xacts = NULL;
+ buffer->n_initial_running_xacts = 0;
+
buffer->spillTxns = 0;
buffer->spillCount = 0;
buffer->spillBytes = 0;
@@ -5154,3 +5157,116 @@ restart:
*cmax = ent->cmax;
return true;
}
+
+/*
+ * Process the transactions in xl_running_xacts record, and remember the
+ * transactions first and later remove those that aren't needed anymore.
+ *
+ * We can ideally remove the transactions from the initial running xacts array
+ * once it is finished (committed/aborted) but that could be costly as we need
+ * to maintain the xids order in the array.
+ */
+void
+ReorderBufferProcessInitialXacts(ReorderBuffer *rb, xl_running_xacts *running)
+{
+ LogicalDecodingContext *ctx = rb->private_data;
+ SnapBuild *builder = ctx->snapshot_builder;
+ TransactionId *workspace;
+ int surviving_xids = 0;
+
+ /* Build the initial running transactions list for the first call */
+ if (unlikely(SnapBuildCurrentState(builder) == SNAPBUILD_START))
+ {
+ int nxacts = running->subxcnt + running->xcnt;
+ Size sz = sizeof(TransactionId) * nxacts;
+
+ Assert(rb->n_initial_running_xacts == 0);
+
+ rb->n_initial_running_xacts = nxacts;
+ rb->initial_running_xacts = MemoryContextAlloc(rb->context, sz);
+ memcpy(rb->initial_running_xacts, running->xids, sz);
+ qsort(rb->initial_running_xacts, nxacts, sizeof(TransactionId),
+ xidComparator);
+
+ return;
+ }
+
+ /* Quick exit if there is no initial running transactions */
+ if (likely(rb->n_initial_running_xacts == 0))
+ return;
+
+ /* bound check if there is at least one transaction to remove */
+ if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
+ running->oldestRunningXid))
+ return;
+
+ /*
+ * Remove transactions that would have been processed and we don't need to
+ * keep track off anymore.
+ *
+ * The purged array must also be sorted in xidComparator order.
+ */
+ workspace = MemoryContextAlloc(rb->context,
+ rb->n_initial_running_xacts * sizeof(TransactionId));
+ for (int i = 0; i < rb->n_initial_running_xacts; i++)
+ {
+ if (NormalTransactionIdPrecedes(rb->initial_running_xacts[i],
+ running->oldestRunningXid))
+ ; /* remove */
+ else
+ workspace[surviving_xids++] = rb->initial_running_xacts[i];
+ }
+
+ if (surviving_xids > 0)
+ memcpy(rb->initial_running_xacts, workspace,
+ sizeof(TransactionId) * surviving_xids);
+ else
+ {
+ pfree(rb->initial_running_xacts);
+ rb->initial_running_xacts = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, oldest running xid %u",
+ (uint32) rb->n_initial_running_xacts,
+ (uint32) surviving_xids,
+ running->oldestRunningXid);
+
+ rb->n_initial_running_xacts = surviving_xids;
+ pfree(workspace);
+}
+
+/*
+ * If the given xid is in the list of the initial running xacts, we mark both it
+ * and its subtransactions as containing catalog changes if not yet.
+ */
+void
+ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt, TransactionId *subxacts,
+ XLogRecPtr lsn)
+{
+ /*
+ * Skip if there is no initial running xacts information or the
+ * transaction is already marked as containing catalog changes.
+ */
+ if (likely(rb->n_initial_running_xacts == 0 ||
+ ReorderBufferXidHasCatalogChanges(rb, xid)))
+ return;
+
+ /*
+ * If this committed transaction is the one that was running at the time
+ * when decoding the first RUNNING_XACTS record and have done catalog
+ * changes, we can mark both the top transaction and its subtransactions
+ * as containing catalog changes.
+ */
+ if (bsearch(&xid, rb->initial_running_xacts, rb->n_initial_running_xacts,
+ sizeof(TransactionId), xidComparator) != NULL)
+ {
+ ReorderBufferXidSetCatalogChanges(rb, xid, lsn);
+
+ for (int i = 0; i < subxcnt; i++)
+ {
+ ReorderBufferAssignChild(rb, xid, subxacts[i], lsn);
+ ReorderBufferXidSetCatalogChanges(rb, subxacts[i], lsn);
+ }
+ }
+}
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index ba257d81b5..fe0f52d4e1 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -12,6 +12,7 @@
#include "access/htup_details.h"
#include "lib/ilist.h"
#include "storage/sinval.h"
+#include "storage/standby.h"
#include "utils/hsearch.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
@@ -589,6 +590,35 @@ struct ReorderBuffer
/* memory accounting */
Size size;
+ /*
+ * Array of transactions and subtransactions that were running when
+ * the xl_running_xacts record that we decoded first was written.
+ * The array is sorted in xidComparator order. Xids are removed from
+ * the array when decoding xl_running_xacts record, and then the array
+ * eventually becomes an empty.
+ *
+ * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
+ * if the transaction has changed the catalog, and that information
+ * is not serialized to SnapBuilder. Therefore, if the logical
+ * decoding decodes the commit record of the transaction that actually
+ * has done catalog changes without these records, we miss to add
+ * the xid to the snapshot, and end up looking at catalogs with the
+ * wrong snapshot. To avoid this problem, if the COMMIT record of
+ * the xid listed in initial_running_xacts has XACT_XINFO_HAS_INVALS
+ * flag, we mark both the top transaction and its substransactions
+ * as containing catalog changes.
+ *
+ * We could end up adding the transaction that didn't change catalog
+ * to the snapshot since we cannot distinguish whether the transaction
+ * has catalog changes only by checking the COMMIT record. It doesn't
+ * have the information on which (sub) transaction has catalog changes,
+ * and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the
+ * transaction has catalog change. But it doesn't become a problem since
+ * we use historic snapshot only for reading system catalogs.
+ */
+ TransactionId *initial_running_xacts;
+ int n_initial_running_xacts;
+
/*
* Statistics about transactions spilled to disk.
*
@@ -678,4 +708,10 @@ void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
void StartupReorderBuffer(void);
+void ReorderBufferProcessInitialXacts(ReorderBuffer *rb,
+ xl_running_xacts *running);
+void ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt,
+ TransactionId *subxacts,
+ XLogRecPtr lsn);
#endif
--
2.24.3 (Apple Git-128)
[application/octet-stream] REL11-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch (15.1K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/5-REL11-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch)
download | inline diff:
From 99f61380e562afbe70f2c0bbd5b025d18c5c36f8 Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Sun, 17 Jul 2022 07:30:23 +0900
Subject: [PATCH v6] Fix catalog lookup with the wrong snapshot during logical
decoding.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change the reorder buffer so that it
remembers the initial running transaction written in the
xl_running_xacts record that we decoded first, and mark the
transaction as containing catalog changes if it’s in the list of the
initial running transactions and its commit record has
XACT_XINFO_HAS_INVALS.
This has false positive; we could end up adding the transaction that
didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the
COMMIT record. It doesn’t have the information on which (sub)
transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't
necessarily indicate that the transaction has catalog change. But it
doesn't become a problem since we use historic snapshot only for
reading system catalogs.
On the master branch, we took a more future-proof approach of writing
catalog modifying transactions to the serialized snapshot. But we
cannot backpatch it because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 44 +++++++
.../specs/catalog_change_snapshot.spec | 39 ++++++
src/backend/replication/logical/decode.c | 17 +++
.../replication/logical/reorderbuffer.c | 116 ++++++++++++++++++
src/include/replication/reorderbuffer.h | 36 ++++++
6 files changed, 253 insertions(+), 1 deletion(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index 65a91a8014..973b94738a 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -51,7 +51,7 @@ regresscheck-install-force: | submake-regress submake-test_decoding temp-install
$(REGRESSCHECKS)
ISOLATIONCHECKS=mxact delayed_startup ondisk_startup concurrent_ddl_dml \
- oldest_xmin snapshot_transfer subxact_without_top
+ oldest_xmin snapshot_transfer subxact_without_top catalog_change_snapshot
isolationcheck: | submake-isolation submake-test_decoding temp-install
$(pg_isolation_regress_check) \
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..dc4f9b7018
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,44 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+---------------------------------------
+BEGIN
+table public.tbl1: TRUNCATE: (no-flags)
+COMMIT
+(3 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..662760fbcf
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACT record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the XACT_RUNNING record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACT
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index c085f7b0f3..9c483ddc12 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -320,6 +320,9 @@ DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
xl_running_xacts *running = (xl_running_xacts *) XLogRecGetData(r);
+ /* Process the initial running transactions, if any */
+ ReorderBufferProcessInitialXacts(ctx->reorder, running);
+
SnapBuildProcessRunningXacts(builder, buf->origptr, running);
/*
@@ -576,6 +579,20 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
commit_time = parsed->origin_timestamp;
}
+ /*
+ * If the COMMIT record has invalidation messages, it could have catalog
+ * changes. We check if it's in the list of the initial running transactions
+ * and then mark it as containing catalog change.
+ *
+ * This must be done before SnapBuildCommitTxn() so that we can include
+ * catalog change transactions to the historic snapshot.
+ */
+ if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
+ ReorderBufferInitialXactsSetCatalogChanges(ctx->reorder, xid,
+ parsed->nsubxacts,
+ parsed->subxacts,
+ buf->origptr);
+
/*
* Process invalidation messages, even if we're not interested in the
* transaction's contents, since the various caches need to always be
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 6c9b5dbced..495135a9f6 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -271,6 +271,9 @@ ReorderBufferAllocate(void)
buffer->outbuf = NULL;
buffer->outbufsize = 0;
+ buffer->initial_running_xacts = NULL;
+ buffer->n_initial_running_xacts = 0;
+
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
@@ -3571,3 +3574,116 @@ restart:
*cmax = ent->cmax;
return true;
}
+
+/*
+ * Process the transactions in xl_running_xacts record, and remember the
+ * transactions first and later remove those that aren't needed anymore.
+ *
+ * We can ideally remove the transactions from the initial running xacts array
+ * once it is finished (committed/aborted) but that could be costly as we need
+ * to maintain the xids order in the array.
+ */
+void
+ReorderBufferProcessInitialXacts(ReorderBuffer *rb, xl_running_xacts *running)
+{
+ LogicalDecodingContext *ctx = rb->private_data;
+ SnapBuild *builder = ctx->snapshot_builder;
+ TransactionId *workspace;
+ int surviving_xids = 0;
+
+ /* Build the initial running transactions list for the first call */
+ if (unlikely(SnapBuildCurrentState(builder) == SNAPBUILD_START))
+ {
+ int nxacts = running->subxcnt + running->xcnt;
+ Size sz = sizeof(TransactionId) * nxacts;
+
+ Assert(rb->n_initial_running_xacts == 0);
+
+ rb->n_initial_running_xacts = nxacts;
+ rb->initial_running_xacts = MemoryContextAlloc(rb->context, sz);
+ memcpy(rb->initial_running_xacts, running->xids, sz);
+ qsort(rb->initial_running_xacts, nxacts, sizeof(TransactionId),
+ xidComparator);
+
+ return;
+ }
+
+ /* Quick exit if there is no initial running transactions */
+ if (likely(rb->n_initial_running_xacts == 0))
+ return;
+
+ /* bound check if there is at least one transaction to remove */
+ if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
+ running->oldestRunningXid))
+ return;
+
+ /*
+ * Remove transactions that would have been processed and we don't need to
+ * keep track off anymore.
+ *
+ * The purged array must also be sorted in xidComparator order.
+ */
+ workspace = MemoryContextAlloc(rb->context,
+ rb->n_initial_running_xacts * sizeof(TransactionId));
+ for (int i = 0; i < rb->n_initial_running_xacts; i++)
+ {
+ if (NormalTransactionIdPrecedes(rb->initial_running_xacts[i],
+ running->oldestRunningXid))
+ ; /* remove */
+ else
+ workspace[surviving_xids++] = rb->initial_running_xacts[i];
+ }
+
+ if (surviving_xids > 0)
+ memcpy(rb->initial_running_xacts, workspace,
+ sizeof(TransactionId) * surviving_xids);
+ else
+ {
+ pfree(rb->initial_running_xacts);
+ rb->initial_running_xacts = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, oldest running xid %u",
+ (uint32) rb->n_initial_running_xacts,
+ (uint32) surviving_xids,
+ running->oldestRunningXid);
+
+ rb->n_initial_running_xacts = surviving_xids;
+ pfree(workspace);
+}
+
+/*
+ * If the given xid is in the list of the initial running xacts, we mark both it
+ * and its subtransactions as containing catalog changes if not yet.
+ */
+void
+ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt, TransactionId *subxacts,
+ XLogRecPtr lsn)
+{
+ /*
+ * Skip if there is no initial running xacts information or the
+ * transaction is already marked as containing catalog changes.
+ */
+ if (likely(rb->n_initial_running_xacts == 0 ||
+ ReorderBufferXidHasCatalogChanges(rb, xid)))
+ return;
+
+ /*
+ * If this committed transaction is the one that was running at the time
+ * when decoding the first RUNNING_XACTS record and have done catalog
+ * changes, we can mark both the top transaction and its subtransactions
+ * as containing catalog changes.
+ */
+ if (bsearch(&xid, rb->initial_running_xacts, rb->n_initial_running_xacts,
+ sizeof(TransactionId), xidComparator) != NULL)
+ {
+ ReorderBufferXidSetCatalogChanges(rb, xid, lsn);
+
+ for (int i = 0; i < subxcnt; i++)
+ {
+ ReorderBufferAssignChild(rb, xid, subxacts[i], lsn);
+ ReorderBufferXidSetCatalogChanges(rb, subxacts[i], lsn);
+ }
+ }
+}
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 3686cd2800..e8c6b661ba 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -12,6 +12,7 @@
#include "access/htup_details.h"
#include "lib/ilist.h"
#include "storage/sinval.h"
+#include "storage/standby.h"
#include "utils/hsearch.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
@@ -390,6 +391,35 @@ struct ReorderBuffer
XLogRecPtr current_restart_decoding_lsn;
+ /*
+ * Array of transactions and subtransactions that were running when
+ * the xl_running_xacts record that we decoded first was written.
+ * The array is sorted in xidComparator order. Xids are removed from
+ * the array when decoding xl_running_xacts record, and then the array
+ * eventually becomes an empty.
+ *
+ * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
+ * if the transaction has changed the catalog, and that information
+ * is not serialized to SnapBuilder. Therefore, if the logical
+ * decoding decodes the commit record of the transaction that actually
+ * has done catalog changes without these records, we miss to add
+ * the xid to the snapshot, and end up looking at catalogs with the
+ * wrong snapshot. To avoid this problem, if the COMMIT record of
+ * the xid listed in initial_running_xacts has XACT_XINFO_HAS_INVALS
+ * flag, we mark both the top transaction and its substransactions
+ * as containing catalog changes.
+ *
+ * We could end up adding the transaction that didn't change catalog
+ * to the snapshot since we cannot distinguish whether the transaction
+ * has catalog changes only by checking the COMMIT record. It doesn't
+ * have the information on which (sub) transaction has catalog changes,
+ * and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the
+ * transaction has catalog change. But it doesn't become a problem since
+ * we use historic snapshot only for reading system catalogs.
+ */
+ TransactionId *initial_running_xacts;
+ int n_initial_running_xacts;
+
/* buffer for disk<->memory conversions */
char *outbuf;
Size outbufsize;
@@ -444,4 +474,10 @@ void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
void StartupReorderBuffer(void);
+void ReorderBufferProcessInitialXacts(ReorderBuffer *rb,
+ xl_running_xacts *running);
+void ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt,
+ TransactionId *subxacts,
+ XLogRecPtr lsn);
#endif
--
2.24.3 (Apple Git-128)
[application/octet-stream] REL10-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch (14.9K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/6-REL10-v6-0001-Fix-catalog-lookup-with-the-wrong-snapshot-during.patch)
download | inline diff:
From 6140ffb31521bd2bc89201bcb7b550a9adf992ee Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Sun, 17 Jul 2022 21:28:35 +0900
Subject: [PATCH v6] Fix catalog lookup with the wrong snapshot during logical
decoding.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change the reorder buffer so that it
remembers the initial running transaction written in the
xl_running_xacts record that we decoded first, and mark the
transaction as containing catalog changes if it’s in the list of the
initial running transactions and its commit record has
XACT_XINFO_HAS_INVALS.
This has false positive; we could end up adding the transaction that
didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the
COMMIT record. It doesn’t have the information on which (sub)
transaction has catalog changes, and XACT_XINFO_HAS_INVALS doesn't
necessarily indicate that the transaction has catalog change. But it
doesn't become a problem since we use historic snapshot only for
reading system catalogs.
On the master branch, we took a more future-proof approach of writing
catalog modifying transactions to the serialized snapshot. But we
cannot backpatch it because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 41 +++++++
.../specs/catalog_change_snapshot.spec | 39 ++++++
src/backend/replication/logical/decode.c | 17 +++
.../replication/logical/reorderbuffer.c | 116 ++++++++++++++++++
src/include/replication/reorderbuffer.h | 36 ++++++
6 files changed, 250 insertions(+), 1 deletion(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index 2db2b2774b..73bc0fe1fe 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -51,7 +51,7 @@ regresscheck-install-force: | submake-regress submake-test_decoding temp-install
$(REGRESSCHECKS)
ISOLATIONCHECKS=mxact delayed_startup ondisk_startup concurrent_ddl_dml \
- oldest_xmin snapshot_transfer subxact_without_top
+ oldest_xmin snapshot_transfer subxact_without_top catalog_change_snapshot
isolationcheck: | submake-isolation submake-test_decoding temp-install
$(pg_isolation_regress_check) \
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..15f9540b3f
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,41 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..662760fbcf
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACT record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the XACT_RUNNING record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACT
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 6f8920f52c..fa0e9b1f38 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -316,6 +316,9 @@ DecodeStandbyOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
{
xl_running_xacts *running = (xl_running_xacts *) XLogRecGetData(r);
+ /* Process the initial running transactions, if any */
+ ReorderBufferProcessInitialXacts(ctx->reorder, running);
+
SnapBuildProcessRunningXacts(builder, buf->origptr, running);
/*
@@ -552,6 +555,20 @@ DecodeCommit(LogicalDecodingContext *ctx, XLogRecordBuffer *buf,
commit_time = parsed->origin_timestamp;
}
+ /*
+ * If the COMMIT record has invalidation messages, it could have catalog
+ * changes. We check if it's in the list of the initial running transactions
+ * and then mark it as containing catalog change.
+ *
+ * This must be done before SnapBuildCommitTxn() so that we can include
+ * catalog change transactions to the historic snapshot.
+ */
+ if (parsed->xinfo & XACT_XINFO_HAS_INVALS)
+ ReorderBufferInitialXactsSetCatalogChanges(ctx->reorder, xid,
+ parsed->nsubxacts,
+ parsed->subxacts,
+ buf->origptr);
+
/*
* Process invalidation messages, even if we're not interested in the
* transaction's contents, since the various caches need to always be
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 061555652c..661436622f 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -272,6 +272,9 @@ ReorderBufferAllocate(void)
buffer->outbuf = NULL;
buffer->outbufsize = 0;
+ buffer->initial_running_xacts = NULL;
+ buffer->n_initial_running_xacts = 0;
+
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
@@ -3509,3 +3512,116 @@ restart:
*cmax = ent->cmax;
return true;
}
+
+/*
+ * Process the transactions in xl_running_xacts record, and remember the
+ * transactions first and later remove those that aren't needed anymore.
+ *
+ * We can ideally remove the transactions from the initial running xacts array
+ * once it is finished (committed/aborted) but that could be costly as we need
+ * to maintain the xids order in the array.
+ */
+void
+ReorderBufferProcessInitialXacts(ReorderBuffer *rb, xl_running_xacts *running)
+{
+ LogicalDecodingContext *ctx = rb->private_data;
+ SnapBuild *builder = ctx->snapshot_builder;
+ TransactionId *workspace;
+ int surviving_xids = 0;
+
+ /* Build the initial running transactions list for the first call */
+ if (unlikely(SnapBuildCurrentState(builder) == SNAPBUILD_START))
+ {
+ int nxacts = running->subxcnt + running->xcnt;
+ Size sz = sizeof(TransactionId) * nxacts;
+
+ Assert(rb->n_initial_running_xacts == 0);
+
+ rb->n_initial_running_xacts = nxacts;
+ rb->initial_running_xacts = MemoryContextAlloc(rb->context, sz);
+ memcpy(rb->initial_running_xacts, running->xids, sz);
+ qsort(rb->initial_running_xacts, nxacts, sizeof(TransactionId),
+ xidComparator);
+
+ return;
+ }
+
+ /* Quick exit if there is no initial running transactions */
+ if (likely(rb->n_initial_running_xacts == 0))
+ return;
+
+ /* bound check if there is at least one transaction to remove */
+ if (!NormalTransactionIdPrecedes(rb->initial_running_xacts[0],
+ running->oldestRunningXid))
+ return;
+
+ /*
+ * Remove transactions that would have been processed and we don't need to
+ * keep track off anymore.
+ *
+ * The purged array must also be sorted in xidComparator order.
+ */
+ workspace = MemoryContextAlloc(rb->context,
+ rb->n_initial_running_xacts * sizeof(TransactionId));
+ for (int i = 0; i < rb->n_initial_running_xacts; i++)
+ {
+ if (NormalTransactionIdPrecedes(rb->initial_running_xacts[i],
+ running->oldestRunningXid))
+ ; /* remove */
+ else
+ workspace[surviving_xids++] = rb->initial_running_xacts[i];
+ }
+
+ if (surviving_xids > 0)
+ memcpy(rb->initial_running_xacts, workspace,
+ sizeof(TransactionId) * surviving_xids);
+ else
+ {
+ pfree(rb->initial_running_xacts);
+ rb->initial_running_xacts = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, oldest running xid %u",
+ (uint32) rb->n_initial_running_xacts,
+ (uint32) surviving_xids,
+ running->oldestRunningXid);
+
+ rb->n_initial_running_xacts = surviving_xids;
+ pfree(workspace);
+}
+
+/*
+ * If the given xid is in the list of the initial running xacts, we mark both it
+ * and its subtransactions as containing catalog changes if not yet.
+ */
+void
+ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt, TransactionId *subxacts,
+ XLogRecPtr lsn)
+{
+ /*
+ * Skip if there is no initial running xacts information or the
+ * transaction is already marked as containing catalog changes.
+ */
+ if (likely(rb->n_initial_running_xacts == 0 ||
+ ReorderBufferXidHasCatalogChanges(rb, xid)))
+ return;
+
+ /*
+ * If this committed transaction is the one that was running at the time
+ * when decoding the first RUNNING_XACTS record and have done catalog
+ * changes, we can mark both the top transaction and its subtransactions
+ * as containing catalog changes.
+ */
+ if (bsearch(&xid, rb->initial_running_xacts, rb->n_initial_running_xacts,
+ sizeof(TransactionId), xidComparator) != NULL)
+ {
+ ReorderBufferXidSetCatalogChanges(rb, xid, lsn);
+
+ for (int i = 0; i < subxcnt; i++)
+ {
+ ReorderBufferAssignChild(rb, xid, subxacts[i], lsn);
+ ReorderBufferXidSetCatalogChanges(rb, subxacts[i], lsn);
+ }
+ }
+}
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index d4555676d6..956d4e3329 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -12,6 +12,7 @@
#include "access/htup_details.h"
#include "lib/ilist.h"
#include "storage/sinval.h"
+#include "storage/standby.h"
#include "utils/hsearch.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
@@ -376,6 +377,35 @@ struct ReorderBuffer
XLogRecPtr current_restart_decoding_lsn;
+ /*
+ * Array of transactions and subtransactions that were running when
+ * the xl_running_xacts record that we decoded first was written.
+ * The array is sorted in xidComparator order. Xids are removed from
+ * the array when decoding xl_running_xacts record, and then the array
+ * eventually becomes an empty.
+ *
+ * We rely on HEAP2_NEW_CID records and XACT_INVALIDATIONS to know
+ * if the transaction has changed the catalog, and that information
+ * is not serialized to SnapBuilder. Therefore, if the logical
+ * decoding decodes the commit record of the transaction that actually
+ * has done catalog changes without these records, we miss to add
+ * the xid to the snapshot, and end up looking at catalogs with the
+ * wrong snapshot. To avoid this problem, if the COMMIT record of
+ * the xid listed in initial_running_xacts has XACT_XINFO_HAS_INVALS
+ * flag, we mark both the top transaction and its substransactions
+ * as containing catalog changes.
+ *
+ * We could end up adding the transaction that didn't change catalog
+ * to the snapshot since we cannot distinguish whether the transaction
+ * has catalog changes only by checking the COMMIT record. It doesn't
+ * have the information on which (sub) transaction has catalog changes,
+ * and XACT_XINFO_HAS_INVALS doesn't necessarily indicate that the
+ * transaction has catalog change. But it doesn't become a problem since
+ * we use historic snapshot only for reading system catalogs.
+ */
+ TransactionId *initial_running_xacts;
+ int n_initial_running_xacts;
+
/* buffer for disk<->memory conversions */
char *outbuf;
Size outbufsize;
@@ -427,4 +457,10 @@ void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
void StartupReorderBuffer(void);
+void ReorderBufferProcessInitialXacts(ReorderBuffer *rb,
+ xl_running_xacts *running);
+void ReorderBufferInitialXactsSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
+ int subxcnt,
+ TransactionId *subxacts,
+ XLogRecPtr lsn);
#endif
--
2.24.3 (Apple Git-128)
[application/octet-stream] master-v6-0001-Add-catalog-modifying-transactions-to-logical-dec.patch (26.1K, ../CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com/7-master-v6-0001-Add-catalog-modifying-transactions-to-logical-dec.patch)
download | inline diff:
From 832c8b155da37dd2505218a366053e9c74b4203a Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <[email protected]>
Date: Wed, 6 Jul 2022 12:53:36 +0900
Subject: [PATCH v6] Add catalog modifying transactions to logical decoding
serialized snapshot.
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, if the logical
decoding decodes only the commit record of the transaction that
actually has modified a catalog, we missed adding its XID to the
snapshot. We ended up looking at catalogs with the wrong snapshot.
To fix this problem, this change adds the list of transaction IDs and
sub-transaction IDs, that have modified catalogs and are running when
snapshot serialization, to the serialized snapshot. When decoding a
COMMIT record, we check both the list and the ReorderBuffer to see if
the transaction has modified catalogs.
Since this adds additional information to the serialized snapshot, we
cannot backpatch it. For back branches, we take another approach;
remember the last-running-xacts list of the first decoded
RUNNING_XACTS record and check if the transaction whose commit record
has XACT_XINFO_HAS_INVALS and whose XID is in the list. This doesn't
require any file format changes but the transaction will end up being
added to the snapshot even if it has only relcache invalidations.
This commit bumps SNAPBUILD_VERSION because of change in SnapBuild.
Back-patch to all supported released.
---
contrib/test_decoding/Makefile | 2 +-
.../expected/catalog_change_snapshot.out | 44 +++
.../specs/catalog_change_snapshot.spec | 39 +++
.../replication/logical/reorderbuffer.c | 69 ++++-
src/backend/replication/logical/snapbuild.c | 261 ++++++++++++------
src/include/replication/reorderbuffer.h | 12 +
6 files changed, 339 insertions(+), 88 deletions(-)
create mode 100644 contrib/test_decoding/expected/catalog_change_snapshot.out
create mode 100644 contrib/test_decoding/specs/catalog_change_snapshot.spec
diff --git a/contrib/test_decoding/Makefile b/contrib/test_decoding/Makefile
index b220906479..c7ce603706 100644
--- a/contrib/test_decoding/Makefile
+++ b/contrib/test_decoding/Makefile
@@ -8,7 +8,7 @@ REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
spill slot truncate stream stats twophase twophase_stream
ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
oldest_xmin snapshot_transfer subxact_without_top concurrent_stream \
- twophase_snapshot slot_creation_error
+ twophase_snapshot slot_creation_error catalog_change_snapshot
REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
diff --git a/contrib/test_decoding/expected/catalog_change_snapshot.out b/contrib/test_decoding/expected/catalog_change_snapshot.out
new file mode 100644
index 0000000000..dc4f9b7018
--- /dev/null
+++ b/contrib/test_decoding/expected/catalog_change_snapshot.out
@@ -0,0 +1,44 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s0_init s0_begin s0_savepoint s0_truncate s1_checkpoint s1_get_changes s0_commit s0_begin s0_insert s1_checkpoint s1_get_changes s0_commit s1_get_changes
+step s0_init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
+?column?
+--------
+init
+(1 row)
+
+step s0_begin: BEGIN;
+step s0_savepoint: SAVEPOINT sp1;
+step s0_truncate: TRUNCATE tbl1;
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+----
+(0 rows)
+
+step s0_commit: COMMIT;
+step s0_begin: BEGIN;
+step s0_insert: INSERT INTO tbl1 VALUES (1);
+step s1_checkpoint: CHECKPOINT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+---------------------------------------
+BEGIN
+table public.tbl1: TRUNCATE: (no-flags)
+COMMIT
+(3 rows)
+
+step s0_commit: COMMIT;
+step s1_get_changes: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0');
+data
+-------------------------------------------------------------
+BEGIN
+table public.tbl1: INSERT: val1[integer]:1 val2[integer]:null
+COMMIT
+(3 rows)
+
+?column?
+--------
+stop
+(1 row)
+
diff --git a/contrib/test_decoding/specs/catalog_change_snapshot.spec b/contrib/test_decoding/specs/catalog_change_snapshot.spec
new file mode 100644
index 0000000000..2971ddc69c
--- /dev/null
+++ b/contrib/test_decoding/specs/catalog_change_snapshot.spec
@@ -0,0 +1,39 @@
+# Test decoding only the commit record of the transaction that have
+# modified catalogs.
+setup
+{
+ DROP TABLE IF EXISTS tbl1;
+ CREATE TABLE tbl1 (val1 integer, val2 integer);
+}
+
+teardown
+{
+ DROP TABLE tbl1;
+ SELECT 'stop' FROM pg_drop_replication_slot('isolation_slot');
+}
+
+session "s0"
+setup { SET synchronous_commit=on; }
+step "s0_init" { SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); }
+step "s0_begin" { BEGIN; }
+step "s0_savepoint" { SAVEPOINT sp1; }
+step "s0_truncate" { TRUNCATE tbl1; }
+step "s0_insert" { INSERT INTO tbl1 VALUES (1); }
+step "s0_commit" { COMMIT; }
+
+session "s1"
+setup { SET synchronous_commit=on; }
+step "s1_checkpoint" { CHECKPOINT; }
+step "s1_get_changes" { SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'skip-empty-xacts', '1', 'include-xids', '0'); }
+
+# For the transaction that TRUNCATEd the table tbl1, the last decoding decodes
+# only its COMMIT record, because it starts from the RUNNING_XACTS record emitted
+# during the first checkpoint execution. This transaction must be marked as
+# containing catalog changes while decoding the COMMIT record and the decoding
+# of the INSERT record must read the pg_class with the correct historic snapshot.
+#
+# Note that in a case where bgwriter wrote the RUNNING_XACTS record between "s0_commit"
+# and "s0_begin", this doesn't happen as the decoding starts from the RUNNING_XACTS
+# record written by bgwriter. One might think we can either stop the bgwriter or
+# increase LOG_SNAPSHOT_INTERVAL_MS but it's not practical via tests.
+permutation "s0_init" "s0_begin" "s0_savepoint" "s0_truncate" "s1_checkpoint" "s1_get_changes" "s0_commit" "s0_begin" "s0_insert" "s1_checkpoint" "s1_get_changes" "s0_commit" "s1_get_changes"
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 88a37fde72..d7f430623d 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -349,6 +349,8 @@ ReorderBufferAllocate(void)
buffer->by_txn_last_xid = InvalidTransactionId;
buffer->by_txn_last_txn = NULL;
+ buffer->catchange_ntxns = 0;
+
buffer->outbuf = NULL;
buffer->outbufsize = 0;
buffer->size = 0;
@@ -366,6 +368,7 @@ ReorderBufferAllocate(void)
dlist_init(&buffer->toplevel_by_lsn);
dlist_init(&buffer->txns_by_base_snapshot_lsn);
+ dlist_init(&buffer->catchange_txns);
/*
* Ensure there's no stale data from prior uses of this slot, in case some
@@ -1526,7 +1529,7 @@ ReorderBufferCleanupTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
}
/*
- * Remove TXN from its containing list.
+ * Remove TXN from its containing lists.
*
* Note: if txn is known as subxact, we are deleting the TXN from its
* parent's list of known subxacts; this leaves the parent's nsubxacts
@@ -1535,6 +1538,14 @@ ReorderBufferCleanupTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
*/
dlist_delete(&txn->node);
+ if (rbtxn_has_catalog_changes(txn))
+ {
+ dlist_delete(&txn->catchange_node);
+ rb->catchange_ntxns--;
+
+ Assert(rb->catchange_ntxns >= 0);
+ }
+
/* now remove reference from buffer */
hash_search(rb->by_txn,
(void *) &txn->xid,
@@ -3275,10 +3286,16 @@ ReorderBufferXidSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
+ ReorderBufferTXN *toptxn;
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
- txn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
+ if (!rbtxn_has_catalog_changes(txn))
+ {
+ txn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
+ dlist_push_tail(&rb->catchange_txns, &txn->catchange_node);
+ rb->catchange_ntxns++;
+ }
/*
* Mark top-level transaction as having catalog changes too if one of its
@@ -3286,8 +3303,52 @@ ReorderBufferXidSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
* conveniently check just top-level transaction and decide whether to
* build the hash table or not.
*/
- if (txn->toptxn != NULL)
- txn->toptxn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
+ toptxn = txn->toptxn;
+ if (toptxn != NULL && !rbtxn_has_catalog_changes(toptxn))
+ {
+ toptxn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
+ dlist_push_tail(&rb->catchange_txns, &toptxn->catchange_node);
+ rb->catchange_ntxns++;
+ }
+}
+
+/*
+ * Return palloc'ed array of the transactions that have changed catalogs.
+ * The returned array is sorted in xidComparator order.
+ *
+ * The caller must free the returned array when done with it.
+ */
+TransactionId *
+ReorderBufferGetCatalogChangesXacts(ReorderBuffer *rb)
+{
+ dlist_iter iter;
+ TransactionId *xids = NULL;
+ size_t xcnt = 0;
+
+ /* Quick return if the list is empty */
+ if (dlist_is_empty(&rb->catchange_txns))
+ {
+ Assert(rb->catchange_ntxns == 0);
+ return NULL;
+ }
+
+ /* Initialize XID array */
+ xids = (TransactionId *) palloc(sizeof(TransactionId) * rb->catchange_ntxns);
+ dlist_foreach(iter, &rb->catchange_txns)
+ {
+ ReorderBufferTXN *txn = dlist_container(ReorderBufferTXN,
+ catchange_node,
+ iter.cur);
+
+ Assert(rbtxn_has_catalog_changes(txn));
+
+ xids[xcnt++] = txn->xid;
+ }
+
+ qsort(xids, xcnt, sizeof(TransactionId), xidComparator);
+
+ Assert((xcnt > 0) && (xcnt == rb->catchange_ntxns));
+ return xids;
}
/*
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 73c0f15214..dce8da9e25 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -241,6 +241,30 @@ struct SnapBuild
*/
TransactionId *xip;
} committed;
+
+ /*
+ * Array of transactions and subtransactions that had modified catalogs
+ * and were running when the snapshot was serialized.
+ *
+ * We normally rely on HEAP2_NEW_CID and XLOG_XACT_INVALIDATIONS records to
+ * know if the transaction has changed the catalog. But it could happen that
+ * the logical decoding decodes only the commit record of the transaction.
+ * This array keeps track of the transactions that have modified catalogs
+ * and were running when serializing a snapshot, and this array is used to
+ * add such transactions to the snapshot.
+ *
+ * This array is set once when restoring the snapshot, xids are removed
+ * from the array when decoding xl_running_xacts record, and then eventually
+ * becomes empty.
+ */
+ struct
+ {
+ /* number of transactions */
+ size_t xcnt;
+
+ /* This array must be sorted in xidComparator order */
+ TransactionId *xip;
+ } catchange;
};
/*
@@ -250,8 +274,8 @@ struct SnapBuild
static ResourceOwner SavedResourceOwnerDuringExport = NULL;
static bool ExportInProgress = false;
-/* ->committed manipulation */
-static void SnapBuildPurgeCommittedTxn(SnapBuild *builder);
+/* ->committed and ->catchange manipulation */
+static void SnapBuildPurgeOlderTxn(SnapBuild *builder);
/* snapshot building/manipulation/distribution functions */
static Snapshot SnapBuildBuildSnapshot(SnapBuild *builder);
@@ -262,6 +286,8 @@ static void SnapBuildSnapIncRefcount(Snapshot snap);
static void SnapBuildDistributeNewCatalogSnapshot(SnapBuild *builder, XLogRecPtr lsn);
+static inline bool SnapBuildXidHasCatalogChanges(SnapBuild *builder, TransactionId xid);
+
/* xlog reading helper functions for SnapBuildProcessRunningXacts */
static bool SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *running);
static void SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff);
@@ -269,6 +295,7 @@ static void SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutof
/* serialization functions */
static void SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn);
static bool SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn);
+static void SnapBuildRestoreContents(int fd, char *dest, Size size, const char *path);
/*
* Allocate a new snapshot builder.
@@ -306,6 +333,9 @@ AllocateSnapshotBuilder(ReorderBuffer *reorder,
palloc0(builder->committed.xcnt_space * sizeof(TransactionId));
builder->committed.includes_all_transactions = true;
+ builder->catchange.xcnt = 0;
+ builder->catchange.xip = NULL;
+
builder->initial_xmin_horizon = xmin_horizon;
builder->start_decoding_at = start_lsn;
builder->building_full_snapshot = need_full_snapshot;
@@ -888,12 +918,15 @@ SnapBuildAddCommittedTxn(SnapBuild *builder, TransactionId xid)
}
/*
- * Remove knowledge about transactions we treat as committed that are smaller
- * than ->xmin. Those won't ever get checked via the ->committed array but via
- * the clog machinery, so we don't need to waste memory on them.
+ * Remove knowledge about transactions we treat as committed or containing catalog
+ * changes that are smaller than ->xmin. Those won't ever get checked via
+ * the ->committed or ->catchange array, respectively. The committed xids will
+ * get checked via the clog machinery. We can ideally remove the transaction
+ * from catchange array once it is finished (committed/aborted) but that could
+ * be costly as we need to maintain the xids order in the array.
*/
static void
-SnapBuildPurgeCommittedTxn(SnapBuild *builder)
+SnapBuildPurgeOlderTxn(SnapBuild *builder)
{
int off;
TransactionId *workspace;
@@ -928,6 +961,40 @@ SnapBuildPurgeCommittedTxn(SnapBuild *builder)
builder->committed.xcnt = surviving_xids;
pfree(workspace);
+
+ /*
+ * purge xids in ->catchange as well. The purged array must also be
+ * sorted in xidComparator order.
+ */
+ if (builder->catchange.xcnt > 0)
+ {
+ /*
+ * Since catchange.xip is sorted, we find the lower bound of
+ * xids that still are interesting.
+ */
+ for (off = 0; off < builder->catchange.xcnt; off++)
+ {
+ if (TransactionIdFollowsOrEquals(builder->catchange.xip[off],
+ builder->xmin))
+ break;
+ }
+
+ surviving_xids = builder->catchange.xcnt - off;
+ if (surviving_xids > 0)
+ memmove(builder->catchange.xip, &(builder->catchange.xip[off]),
+ surviving_xids * sizeof(TransactionId));
+ else
+ {
+ /* catchange list becomes empty */
+ pfree(builder->catchange.xip);
+ builder->catchange.xip = NULL;
+ }
+
+ elog(DEBUG3, "purged catalog modifying transactions from %u to %u, xmin %u",
+ (uint32) builder->catchange.xcnt, (uint32) surviving_xids,
+ builder->xmin);
+ builder->catchange.xcnt = surviving_xids;
+ }
}
/*
@@ -983,7 +1050,7 @@ SnapBuildCommitTxn(SnapBuild *builder, XLogRecPtr lsn, TransactionId xid,
* Add subtransaction to base snapshot if catalog modifying, we don't
* distinguish to toplevel transactions there.
*/
- if (ReorderBufferXidHasCatalogChanges(builder->reorder, subxid))
+ if (SnapBuildXidHasCatalogChanges(builder, subxid))
{
sub_needs_timetravel = true;
needs_snapshot = true;
@@ -1012,7 +1079,7 @@ SnapBuildCommitTxn(SnapBuild *builder, XLogRecPtr lsn, TransactionId xid,
}
/* if top-level modified catalog, it'll need a snapshot */
- if (ReorderBufferXidHasCatalogChanges(builder->reorder, xid))
+ if (SnapBuildXidHasCatalogChanges(builder, xid))
{
elog(DEBUG2, "found top level transaction %u, with catalog changes",
xid);
@@ -1089,6 +1156,21 @@ SnapBuildCommitTxn(SnapBuild *builder, XLogRecPtr lsn, TransactionId xid,
}
}
+/*
+ * Check both the reorder buffer and the snapshot to see if the given
+ * transaction has modified catalogs.
+ */
+static inline bool
+SnapBuildXidHasCatalogChanges(SnapBuild *builder, TransactionId xid)
+{
+ if (ReorderBufferXidHasCatalogChanges(builder->reorder, xid))
+ return true;
+
+ /* Check the catchange XID array */
+ return ((builder->catchange.xcnt > 0) &&
+ (bsearch(&xid, builder->catchange.xip, builder->catchange.xcnt,
+ sizeof(TransactionId), xidComparator) != NULL));
+}
/* -----------------------------------
* Snapshot building functions dealing with xlog records
@@ -1135,7 +1217,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
builder->xmin = running->oldestRunningXid;
/* Remove transactions we don't need to keep track off anymore */
- SnapBuildPurgeCommittedTxn(builder);
+ SnapBuildPurgeOlderTxn(builder);
/*
* Advance the xmin limit for the current replication slot, to allow
@@ -1438,6 +1520,7 @@ SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff)
*
* struct SnapBuildOnDisk;
* TransactionId * committed.xcnt; (*not xcnt_space*)
+ * TransactionId * catchange.xcnt;
*
*/
typedef struct SnapBuildOnDisk
@@ -1467,7 +1550,7 @@ typedef struct SnapBuildOnDisk
offsetof(SnapBuildOnDisk, version)
#define SNAPBUILD_MAGIC 0x51A1E001
-#define SNAPBUILD_VERSION 4
+#define SNAPBUILD_VERSION 5
/*
* Store/Load a snapshot from disk, depending on the snapshot builder's state.
@@ -1493,6 +1576,8 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
{
Size needed_length;
SnapBuildOnDisk *ondisk = NULL;
+ TransactionId *catchange_xip = NULL;
+ size_t catchange_xcnt;
char *ondisk_c;
int fd;
char tmppath[MAXPGPATH];
@@ -1578,8 +1663,12 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m", tmppath)));
+ /* Get the catalog modifying transactions that are yet not committed */
+ catchange_xip = ReorderBufferGetCatalogChangesXacts(builder->reorder);
+ catchange_xcnt = builder->reorder->catchange_ntxns;
+
needed_length = sizeof(SnapBuildOnDisk) +
- sizeof(TransactionId) * builder->committed.xcnt;
+ sizeof(TransactionId) * (builder->committed.xcnt + catchange_xcnt);
ondisk_c = MemoryContextAllocZero(builder->context, needed_length);
ondisk = (SnapBuildOnDisk *) ondisk_c;
@@ -1598,16 +1687,31 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
ondisk->builder.snapshot = NULL;
ondisk->builder.reorder = NULL;
ondisk->builder.committed.xip = NULL;
+ ondisk->builder.catchange.xip = NULL;
+ /* update catchange only on disk data */
+ ondisk->builder.catchange.xcnt = catchange_xcnt;
COMP_CRC32C(ondisk->checksum,
&ondisk->builder,
sizeof(SnapBuild));
/* copy committed xacts */
- sz = sizeof(TransactionId) * builder->committed.xcnt;
- memcpy(ondisk_c, builder->committed.xip, sz);
- COMP_CRC32C(ondisk->checksum, ondisk_c, sz);
- ondisk_c += sz;
+ if (builder->committed.xcnt > 0)
+ {
+ sz = sizeof(TransactionId) * builder->committed.xcnt;
+ memcpy(ondisk_c, builder->committed.xip, sz);
+ COMP_CRC32C(ondisk->checksum, ondisk_c, sz);
+ ondisk_c += sz;
+ }
+
+ /* copy catalog modifying xacts */
+ if (catchange_xcnt > 0)
+ {
+ sz = sizeof(TransactionId) * catchange_xcnt;
+ memcpy(ondisk_c, catchange_xip, sz);
+ COMP_CRC32C(ondisk->checksum, ondisk_c, sz);
+ ondisk_c += sz;
+ }
FIN_CRC32C(ondisk->checksum);
@@ -1694,6 +1798,8 @@ out:
/* be tidy */
if (ondisk)
pfree(ondisk);
+ if (catchange_xip)
+ pfree(catchange_xip);
}
/*
@@ -1707,7 +1813,6 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
int fd;
char path[MAXPGPATH];
Size sz;
- int readBytes;
pg_crc32c checksum;
/* no point in loading a snapshot if we're already there */
@@ -1739,29 +1844,7 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
/* read statically sized portion of snapshot */
- pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
- readBytes = read(fd, &ondisk, SnapBuildOnDiskConstantSize);
- pgstat_report_wait_end();
- if (readBytes != SnapBuildOnDiskConstantSize)
- {
- int save_errno = errno;
-
- CloseTransientFile(fd);
-
- if (readBytes < 0)
- {
- errno = save_errno;
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not read file \"%s\": %m", path)));
- }
- else
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg("could not read file \"%s\": read %d of %zu",
- path, readBytes,
- (Size) SnapBuildOnDiskConstantSize)));
- }
+ SnapBuildRestoreContents(fd, (char *) &ondisk, SnapBuildOnDiskConstantSize, path);
if (ondisk.magic != SNAPBUILD_MAGIC)
ereport(ERROR,
@@ -1781,56 +1864,26 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
SnapBuildOnDiskConstantSize - SnapBuildOnDiskNotChecksummedSize);
/* read SnapBuild */
- pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
- readBytes = read(fd, &ondisk.builder, sizeof(SnapBuild));
- pgstat_report_wait_end();
- if (readBytes != sizeof(SnapBuild))
- {
- int save_errno = errno;
-
- CloseTransientFile(fd);
-
- if (readBytes < 0)
- {
- errno = save_errno;
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not read file \"%s\": %m", path)));
- }
- else
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg("could not read file \"%s\": read %d of %zu",
- path, readBytes, sizeof(SnapBuild))));
- }
+ SnapBuildRestoreContents(fd, (char *) &ondisk.builder, sizeof(SnapBuild), path);
COMP_CRC32C(checksum, &ondisk.builder, sizeof(SnapBuild));
/* restore committed xacts information */
- sz = sizeof(TransactionId) * ondisk.builder.committed.xcnt;
- ondisk.builder.committed.xip = MemoryContextAllocZero(builder->context, sz);
- pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
- readBytes = read(fd, ondisk.builder.committed.xip, sz);
- pgstat_report_wait_end();
- if (readBytes != sz)
+ if (ondisk.builder.committed.xcnt > 0)
{
- int save_errno = errno;
-
- CloseTransientFile(fd);
+ sz = sizeof(TransactionId) * ondisk.builder.committed.xcnt;
+ ondisk.builder.committed.xip = MemoryContextAllocZero(builder->context, sz);
+ SnapBuildRestoreContents(fd, (char *) ondisk.builder.committed.xip, sz, path);
+ COMP_CRC32C(checksum, ondisk.builder.committed.xip, sz);
+ }
- if (readBytes < 0)
- {
- errno = save_errno;
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not read file \"%s\": %m", path)));
- }
- else
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg("could not read file \"%s\": read %d of %zu",
- path, readBytes, sz)));
+ /* restore catalog modifying xacts information */
+ if (ondisk.builder.catchange.xcnt > 0)
+ {
+ sz = sizeof(TransactionId) * ondisk.builder.catchange.xcnt;
+ ondisk.builder.catchange.xip = MemoryContextAllocZero(builder->context, sz);
+ SnapBuildRestoreContents(fd, (char *) ondisk.builder.catchange.xip, sz, path);
+ COMP_CRC32C(checksum, ondisk.builder.catchange.xip, sz);
}
- COMP_CRC32C(checksum, ondisk.builder.committed.xip, sz);
if (CloseTransientFile(fd) != 0)
ereport(ERROR,
@@ -1885,6 +1938,14 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
}
ondisk.builder.committed.xip = NULL;
+ /* set catalog modifying transactions */
+ if (builder->catchange.xip)
+ pfree(builder->catchange.xip);
+ builder->catchange.xcnt = ondisk.builder.catchange.xcnt;
+ builder->catchange.xip = ondisk.builder.catchange.xip;
+
+ ondisk.builder.catchange.xip = NULL;
+
/* our snapshot is not interesting anymore, build a new one */
if (builder->snapshot != NULL)
{
@@ -1906,9 +1967,43 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
snapshot_not_interesting:
if (ondisk.builder.committed.xip != NULL)
pfree(ondisk.builder.committed.xip);
+ if (ondisk.builder.catchange.xip != NULL)
+ pfree(ondisk.builder.catchange.xip);
return false;
}
+/*
+ * Read the contents of the serialized snapshot to the dest.
+ */
+static void
+SnapBuildRestoreContents(int fd, char *dest, Size size, const char *path)
+{
+ int readBytes;
+
+ pgstat_report_wait_start(WAIT_EVENT_SNAPBUILD_READ);
+ readBytes = read(fd, dest, size);
+ pgstat_report_wait_end();
+ if (readBytes != size)
+ {
+ int save_errno = errno;
+
+ CloseTransientFile(fd);
+
+ if (readBytes < 0)
+ {
+ errno = save_errno;
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not read file \"%s\": %m", path)));
+ }
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg("could not read file \"%s\": read %d of %zu",
+ path, readBytes, sizeof(SnapBuild))));
+ }
+}
+
/*
* Remove all serialized snapshots that are not required anymore because no
* slot can need them. This doesn't actually have to run during a checkpoint,
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index d109d0baed..fd84f175c0 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -380,6 +380,11 @@ typedef struct ReorderBufferTXN
*/
dlist_node node;
+ /*
+ * A node in the list of catalog modifying transactions
+ */
+ dlist_node catchange_node;
+
/*
* Size of this transaction (changes currently in memory, in bytes).
*/
@@ -526,6 +531,12 @@ struct ReorderBuffer
*/
dlist_head txns_by_base_snapshot_lsn;
+ /*
+ * Transactions and subtransactions that have modified system catalogs.
+ */
+ dlist_head catchange_txns;
+ int catchange_ntxns;
+
/*
* one-entry sized cache for by_txn. Very frequently the same txn gets
* looked up over and over again.
@@ -677,6 +688,7 @@ extern void ReorderBufferSkipPrepare(ReorderBuffer *rb, TransactionId xid);
extern void ReorderBufferPrepare(ReorderBuffer *rb, TransactionId xid, char *gid);
extern ReorderBufferTXN *ReorderBufferGetOldestTXN(ReorderBuffer *);
extern TransactionId ReorderBufferGetOldestXmin(ReorderBuffer *rb);
+extern TransactionId *ReorderBufferGetCatalogChangesXacts(ReorderBuffer *rb);
extern void ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
--
2.24.3 (Apple Git-128)
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Subject: Re: [BUG] Logical replication failure "ERROR: could not map filenode "base/13237/442428" to relation OID" with catalog modifying txns
In-Reply-To: <CAD21AoAUx28e-1YQDA6Uhda+=jkidAy+HY8Zv5SYjtXpRcBiVg@mail.gmail.com>
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