| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | Alban Hertroys <haramrae(at)gmail(dot)com>, Job <Job(at)colliniconsulting(dot)it>, Rob Sargent <robjsargent(at)gmail(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Postgres 9.6.1 big slowdown by upgrading 8.4.22 |
| Date: | 2017-01-08 02:37:37 |
| Message-ID: | 13465.1483843057@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> writes:
> No. now() calls GetCurrentTransactionStartTimestamp(), so it does not
> call gettimeofday() and so the clock source overhead is pretty much
> irrelevant. Moreover it's marked as 'stable' which makes repeated calls
> unnecessary.
Yeah. My own thought, in view of the large version jump involved, is that
there's been some change in the planning of semi-joins that isn't working
well here. But since the OP hasn't provided EXPLAIN output for the
problem case, table schemas, or indeed any of the details suggested in
https://wiki.postgresql.org/wiki/Slow_Query_Questions
it's hard to provide any concrete answers.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Shrikant Bhende | 2017-01-08 04:12:05 | Catalog table which stores database level information |
| Previous Message | Tomas Vondra | 2017-01-08 02:28:24 | Re: Postgres 9.6.1 big slowdown by upgrading 8.4.22 |