diff options
Diffstat (limited to 'src/backend/access/transam/slru.c')
| -rw-r--r-- | src/backend/access/transam/slru.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index 61249f4a12d..275058036a2 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -1208,6 +1208,14 @@ SimpleLruFlush(SlruCtl ctl, bool allow_redirtied) /* * Remove all segments before the one holding the passed page number + * + * All SLRUs prevent concurrent calls to this function, either with an LWLock + * or by calling it only as part of a checkpoint. Mutual exclusion must begin + * before computing cutoffPage. Mutual exclusion must end after any limit + * update that would permit other backends to write fresh data into the + * segment immediately preceding the one containing cutoffPage. Otherwise, + * when the SLRU is quite full, SimpleLruTruncate() might delete that segment + * after it has accrued freshly-written data. */ void SimpleLruTruncate(SlruCtl ctl, int cutoffPage) |