diff options
| -rw-r--r-- | src/backend/commands/indexcmds.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index a08ad1324ba..34153f5eb9a 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -142,6 +142,7 @@ DefineIndex(RangeVar *heapRelation, int16 *coloptions; IndexInfo *indexInfo; int numberOfAttributes; + TransactionId limitXmin; VirtualTransactionId *old_lockholders; VirtualTransactionId *old_snapshots; int n_old_snapshots; @@ -577,6 +578,18 @@ DefineIndex(RangeVar *heapRelation, validate_index(relationId, indexRelationId, snapshot); /* + * Drop the reference snapshot. We must do this before waiting out other + * snapshot holders, else we will deadlock against other processes also + * doing CREATE INDEX CONCURRENTLY, which would see our snapshot as one + * they must wait for. But first, save the snapshot's xmin to use as + * limitXmin for GetCurrentVirtualXIDs(). + */ + limitXmin = snapshot->xmin; + + PopActiveSnapshot(); + UnregisterSnapshot(snapshot); + + /* * The index is now valid in the sense that it contains all currently * interesting tuples. But since it might not contain tuples deleted just * before the reference snap was taken, we have to wait out any @@ -608,7 +621,7 @@ DefineIndex(RangeVar *heapRelation, * GetCurrentVirtualXIDs. If, during any iteration, a particular vxid * doesn't show up in the output, we know we can forget about it. */ - old_snapshots = GetCurrentVirtualXIDs(snapshot->xmin, true, false, + old_snapshots = GetCurrentVirtualXIDs(limitXmin, true, false, PROC_IS_AUTOVACUUM | PROC_IN_VACUUM, &n_old_snapshots); @@ -625,7 +638,7 @@ DefineIndex(RangeVar *heapRelation, int j; int k; - newer_snapshots = GetCurrentVirtualXIDs(snapshot->xmin, + newer_snapshots = GetCurrentVirtualXIDs(limitXmin, true, false, PROC_IS_AUTOVACUUM | PROC_IN_VACUUM, &n_newer_snapshots); @@ -664,12 +677,6 @@ DefineIndex(RangeVar *heapRelation, */ CacheInvalidateRelcacheByRelid(heaprelid.relId); - /* we can now do away with our active snapshot */ - PopActiveSnapshot(); - - /* And we can remove the validating snapshot too */ - UnregisterSnapshot(snapshot); - /* * Last thing to do is release the session-level lock on the parent table. */ |