Tom Lane <tgl@xxxxxxxxxxxxx> writes: > =?UTF-8?q?Mart=C3=ADn_Fern=C3=A1ndez?= <fmartin91@xxxxxxxxx> writes: > >> We are experiencing some `vacuum` issues with a given table >> (potentially more). When a manual vacuum runs on the given table it >> seems that the `vacuum` process is not doing the expected cleanup. > >> DETAIL: 113257 dead row versions cannot be removed yet. > > Locks don't really have anything to do with that: what does matter is > how old is the oldest open transaction, because that determines the > "event horizon" that dead row versions have to fall below before they > can be removed. That oldest transaction might not be holding any locks > at the moment, but it doesn't matter, because in principle it could ask > to read this table later --- and it should see the table's contents as > of its snapshot. > > Serializable transactions are worse than repeatable-read transactions > for this purpose, because the former will keep a snapshot as of their > start time. > > As Jerry mentioned, replication slots can also act like open transactions > for this purpose, though I don't recall how much of that behavior is > present in 9.2.x. Oops, didn't notice OP was on 9.2! Presume none, since I don't think we got rep slots till 9.4 :-) > > regards, tom lane > > -- Jerry Sievers Postgres DBA/Development Consulting e: postgres.consulting@xxxxxxxxxxx p: 312.241.7800
