On Tue, Nov 30, 2021 at 5:49 PM Simon Riggs <simon.ri...@enterprisedb.com> wrote:
> transam.c uses a single item cache to prevent thrashing from repeated > lookups, which reduces problems with shared access to SLRUs. > multitrans.c also has similar. > > I notice that subtrans. doesn't have this, but could easily do so. > Patch attached, which seems separate to other attempts at tuning. Yeah, this definitely makes sense. > On review, I think it is also possible that we update subtrans ONLY if > someone uses >PGPROC_MAX_CACHED_SUBXIDS. > This would make subtrans much smaller and avoid one-entry-per-page > which is a major source of cacheing. > This would means some light changes in GetSnapshotData(). > Let me know if that seems interesting also? Do you mean to say avoid setting the sub-transactions parent if the number of sun-transactions is not crossing PGPROC_MAX_CACHED_SUBXIDS? But the TransactionIdDidCommit(), might need to fetch the parent if the transaction status is TRANSACTION_STATUS_SUB_COMMITTED, so how would we handle that? -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
