diff options
| -rw-r--r-- | src/backend/storage/lmgr/predicate.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index 1af41213b41..a794546db3e 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -1004,7 +1004,7 @@ SerialSetActiveSerXmin(TransactionId xid) void CheckPointPredicate(void) { - int tailPage; + int truncateCutoffPage; LWLockAcquire(SerialSLRULock, LW_EXCLUSIVE); @@ -1017,8 +1017,24 @@ CheckPointPredicate(void) if (TransactionIdIsValid(serialControl->tailXid)) { - /* We can truncate the SLRU up to the page containing tailXid */ + int tailPage; + tailPage = SerialPage(serialControl->tailXid); + + /* + * It is possible for the tailXid to be ahead of the headXid. This + * occurs if we checkpoint while there are in-progress serializable + * transaction(s) advancing the tail but we are yet to summarize the + * transactions. In this case, we cutoff up to the headPage and the + * next summary will advance the headXid. + */ + if (SerialPagePrecedesLogically(tailPage, serialControl->headPage)) + { + /* We can truncate the SLRU up to the page containing tailXid */ + truncateCutoffPage = tailPage; + } + else + truncateCutoffPage = serialControl->headPage; } else { @@ -1051,14 +1067,14 @@ CheckPointPredicate(void) * transaction instigating the summarize fails in * SimpleLruReadPage(). */ - tailPage = serialControl->headPage; + truncateCutoffPage = serialControl->headPage; serialControl->headPage = -1; } LWLockRelease(SerialSLRULock); /* Truncate away pages that are no longer required */ - SimpleLruTruncate(SerialSlruCtl, tailPage); + SimpleLruTruncate(SerialSlruCtl, truncateCutoffPage); /* * Write dirty SLRU pages to disk |