| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rysdam <drysdam(at)ll(dot)mit(dot)edu> |
| Cc: | Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: EXPLAIN ANALYZE output |
| Date: | 2005-12-27 22:36:28 |
| Message-ID: | 4507.1135722988@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
David Rysdam <drysdam(at)ll(dot)mit(dot)edu> writes:
> According to what I've been able to find:
> A = predicted time to first returned row in milliseconds
^^^^^^^^^^^^ arbitrary units
> B = total cost in arbitrary units
> C = actual time to first returned row in milliseconds
> D = actual total time in milliseconds
> 2) Does EXPLAIN ANALYZE add a lot of overhead that is being measured here?
Yes, its per-row overhead can be significant. Depends on what the query
plan actually is, and how many rows go through, which you didn't say...
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tom Lane | 2005-12-27 22:44:10 | Re: [GENERAL] Running with fsync=off |
| Previous Message | Eugene | 2005-12-27 21:25:37 | POSTGRES DB 3 800 000 rows table, speed up? |