mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-16 23:53:22 +02:00
If several sessions are concurrently locking a tuple update chain with nonconflicting lock modes using an old snapshot, and they all succeed, it may happen that some of them fail because of restarting the loop (due to a concurrent Xmax change) and getting an error in the subsequent pass while trying to obtain a tuple lock that they already have in some tuple version. This can only happen with very high concurrency (where a row is being both updated and FK-checked by multiple transactions concurrently), but it's been observed in the field and can have unpleasant consequences such as an FK check failing to see a tuple that definitely exists: ERROR: insert or update on table "child_table" violates foreign key constraint "fk_constraint_name" DETAIL: Key (keyid)=(123456) is not present in table "parent_table". (where the key is observably present in the table). Discussion: https://postgr.es/m/20170714210011.r25mrff4nxjhmf3g@alvherre.pgsql |
||
---|---|---|
.. | ||
brin | ||
common | ||
gin | ||
gist | ||
hash | ||
heap | ||
index | ||
nbtree | ||
rmgrdesc | ||
spgist | ||
tablesample | ||
transam | ||
Makefile |