Rearrange logrep worker's snapshot handling some more.
It turns out that worker.c's code path for TRUNCATE was also
careless about establishing a snapshot while executing user-defined
code, allowing the checks added by commit 84f5c2908
to fail when
a trigger is fired in that context.
We could just wrap Push/PopActiveSnapshot around the truncate call,
but it seems better to establish a policy of holding a snapshot
throughout execution of a replication step. To help with that and
possible future requirements, replace the previous ensure_transaction
calls with pairs of begin/end_replication_step calls.
Per report from Mark Dilger. Back-patch to v11, like the previous
changes.
Discussion: https://postgr.es/m/B4A3AF82-79ED-4F4C-A4E5-CD2622098972@enterprisedb.com
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parent
3465328aa1
commit
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@ -169,30 +169,41 @@ should_apply_changes_for_rel(LogicalRepRelMapEntry *rel)
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}
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/*
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* Make sure that we started local transaction.
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* Begin one step (one INSERT, UPDATE, etc) of a replication transaction.
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*
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* Also switches to ApplyMessageContext as necessary.
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* Start a transaction, if this is the first step (else we keep using the
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* existing transaction).
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* Also provide a global snapshot and ensure we run in ApplyMessageContext.
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*/
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static bool
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ensure_transaction(void)
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static void
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begin_replication_step(void)
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{
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if (IsTransactionState())
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SetCurrentStatementStartTimestamp();
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if (!IsTransactionState())
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{
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SetCurrentStatementStartTimestamp();
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if (CurrentMemoryContext != ApplyMessageContext)
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MemoryContextSwitchTo(ApplyMessageContext);
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return false;
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StartTransactionCommand();
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maybe_reread_subscription();
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}
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SetCurrentStatementStartTimestamp();
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StartTransactionCommand();
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maybe_reread_subscription();
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PushActiveSnapshot(GetTransactionSnapshot());
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MemoryContextSwitchTo(ApplyMessageContext);
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return true;
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}
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/*
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* Finish up one step of a replication transaction.
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* Callers of begin_replication_step() must also call this.
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*
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* We don't close out the transaction here, but we should increment
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* the command counter to make the effects of this step visible.
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*/
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static void
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end_replication_step(void)
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{
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PopActiveSnapshot();
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CommandCounterIncrement();
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}
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@ -210,13 +221,6 @@ create_edata_for_relation(LogicalRepRelMapEntry *rel)
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ResultRelInfo *resultRelInfo;
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RangeTblEntry *rte;
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/*
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* Input functions may need an active snapshot, as may AFTER triggers
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* invoked during finish_edata. For safety, ensure an active snapshot
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* exists throughout all our usage of the executor.
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*/
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PushActiveSnapshot(GetTransactionSnapshot());
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edata = (ApplyExecutionData *) palloc0(sizeof(ApplyExecutionData));
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edata->targetRel = rel;
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@ -277,8 +281,6 @@ finish_edata(ApplyExecutionData *edata)
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ExecResetTupleTable(estate->es_tupleTable, false);
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FreeExecutorState(estate);
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pfree(edata);
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PopActiveSnapshot();
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}
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/*
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@ -673,7 +675,7 @@ apply_handle_insert(StringInfo s)
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TupleTableSlot *remoteslot;
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MemoryContext oldctx;
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ensure_transaction();
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begin_replication_step();
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relid = logicalrep_read_insert(s, &newtup);
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rel = logicalrep_rel_open(relid, RowExclusiveLock);
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@ -684,6 +686,7 @@ apply_handle_insert(StringInfo s)
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* transaction so it's safe to unlock it.
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*/
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logicalrep_rel_close(rel, RowExclusiveLock);
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end_replication_step();
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return;
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}
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@ -712,7 +715,7 @@ apply_handle_insert(StringInfo s)
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logicalrep_rel_close(rel, NoLock);
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CommandCounterIncrement();
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end_replication_step();
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}
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/* Workhorse for apply_handle_insert() */
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@ -781,7 +784,7 @@ apply_handle_update(StringInfo s)
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RangeTblEntry *target_rte;
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MemoryContext oldctx;
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ensure_transaction();
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begin_replication_step();
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relid = logicalrep_read_update(s, &has_oldtup, &oldtup,
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&newtup);
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@ -793,6 +796,7 @@ apply_handle_update(StringInfo s)
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* transaction so it's safe to unlock it.
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*/
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logicalrep_rel_close(rel, RowExclusiveLock);
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end_replication_step();
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return;
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}
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@ -849,7 +853,7 @@ apply_handle_update(StringInfo s)
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logicalrep_rel_close(rel, NoLock);
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CommandCounterIncrement();
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end_replication_step();
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}
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/* Workhorse for apply_handle_update() */
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@ -925,7 +929,7 @@ apply_handle_delete(StringInfo s)
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TupleTableSlot *remoteslot;
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MemoryContext oldctx;
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ensure_transaction();
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begin_replication_step();
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relid = logicalrep_read_delete(s, &oldtup);
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rel = logicalrep_rel_open(relid, RowExclusiveLock);
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@ -936,6 +940,7 @@ apply_handle_delete(StringInfo s)
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* transaction so it's safe to unlock it.
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*/
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logicalrep_rel_close(rel, RowExclusiveLock);
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end_replication_step();
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return;
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}
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@ -966,7 +971,7 @@ apply_handle_delete(StringInfo s)
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logicalrep_rel_close(rel, NoLock);
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CommandCounterIncrement();
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end_replication_step();
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}
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/* Workhorse for apply_handle_delete() */
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@ -1291,7 +1296,7 @@ apply_handle_truncate(StringInfo s)
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ListCell *lc;
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LOCKMODE lockmode = AccessExclusiveLock;
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ensure_transaction();
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begin_replication_step();
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remote_relids = logicalrep_read_truncate(s, &cascade, &restart_seqs);
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@ -1379,7 +1384,7 @@ apply_handle_truncate(StringInfo s)
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table_close(rel, NoLock);
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}
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CommandCounterIncrement();
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end_replication_step();
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}
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