On 7/24/23 14:57, Ashutosh Bapat wrote: > ... > >> >> >> 2) Currently, the sequences hash table is in reorderbuffer, i.e. global. >> I was thinking maybe we should have it in the transaction (because we >> need to do cleanup at the end). It seem a bit inconvenient, because then >> we'd need to either search htabs in all subxacts, or transfer the >> entries to the top-level xact (otoh, we already do that with snapshots), >> and cleanup on abort. >> >> What do you think? > > Hash table per transaction seems saner design. Adding it to the top > level transaction should be fine. The entry will contain an XID > anyway. If we add it to every subtransaction we will need to search > hash table in each of the subtransactions when deciding whether a > sequence change is transactional or not. Top transaction is a > reasonable trade off. >
It's not clear to me what design you're proposing, exactly. If we track it in top-level transactions, then we'd need copy the data whenever a transaction is assigned as a child, and perhaps also remove it when there's a subxact abort. And we'd need to still search the hashes in all toplevel transactions on every sequence increment - in principle we can't have increment for a sequence created in another in-progress transaction, but maybe it's just not assigned yet. regards -- Tomas Vondra EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
