On Wed, Sep 20, 2017 at 7:19 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: >> Page-at-a-time index vacuum as in _hash_vacuum_one_page doesn't matter >> because such an operation doesn't allow TIDs to be reused. > > Page-at-a-time index vacuum also allows TIDs to be reused but this is > done only for already marked dead items whereas vacuum can make the > non-dead entries to be removed. We don't have a problem with > page-at-a-time vacuum as it won't remove any items which the scan is > going to mark as dead.
I don't think page-at-a-time index vacuum allows heap TIDs to be reused. To reuse a heap TID, we have to know that there are no index entries pointing to it. There's no way for the heap to know that a page-at-a-time index vacuum has even happened, let alone which TIDs were affected and that all other indexes have also removed all index entries for those TIDs. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
