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| author | Andres Freund <andres@anarazel.de> | 2023-03-11 14:12:51 -0800 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2023-03-11 14:12:51 -0800 |
| commit | 16327240da29b70e41a65d49212b31da9a94e177 (patch) | |
| tree | 8531d28cff4dfac6fa406112c78a270448d9a874 | |
| parent | 4e633016abe9b82053aafb2fe9d3317add73f74d (diff) | |
| download | postgresql-16327240da29b70e41a65d49212b31da9a94e177.tar.gz postgresql-16327240da29b70e41a65d49212b31da9a94e177.zip | |
amcheck: Fix ordering bug in update_cached_xid_range()
The initialization order in update_cached_xid_range() was wrong, calling
FullTransactionIdFromXidAndCtx() before setting
->next_xid. FullTransactionIdFromXidAndCtx() uses ->next_xid.
In most situations this will not cause visible issues, because the next call
to update_cached_xid_range() will use a less wrong ->next_xid. It's rare that
xids advance fast enough for this to be a problem.
Found while adding more asserts to the 64bit xid infrastructure.
Reviewed-by: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://postgr.es/m/20230108002923.cyoser3ttmt63bfn@awork3.anarazel.de
Backpatch: 14-, where heapam verification was introduced
| -rw-r--r-- | contrib/amcheck/verify_heapam.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c index 4fcfd6df72d..33c5b338959 100644 --- a/contrib/amcheck/verify_heapam.c +++ b/contrib/amcheck/verify_heapam.c @@ -1576,6 +1576,9 @@ FullTransactionIdFromXidAndCtx(TransactionId xid, const HeapCheckContext *ctx) { uint32 epoch; + Assert(TransactionIdIsNormal(ctx->next_xid)); + Assert(FullTransactionIdIsNormal(ctx->next_fxid)); + if (!TransactionIdIsNormal(xid)) return FullTransactionIdFromEpochAndXid(0, xid); epoch = EpochFromFullTransactionId(ctx->next_fxid); @@ -1597,8 +1600,8 @@ update_cached_xid_range(HeapCheckContext *ctx) LWLockRelease(XidGenLock); /* And compute alternate versions of the same */ - ctx->oldest_fxid = FullTransactionIdFromXidAndCtx(ctx->oldest_xid, ctx); ctx->next_xid = XidFromFullTransactionId(ctx->next_fxid); + ctx->oldest_fxid = FullTransactionIdFromXidAndCtx(ctx->oldest_xid, ctx); } /* |