From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
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To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeevan Ladhe <jeevan(dot)ladhe(at)enterprisedb(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Binary search in fmgr_isbuiltin() is a bottleneck. |
Date: | 2017-09-27 19:30:45 |
Message-ID: | CA+Tgmob+0YB9R5fnCrHdVAZePjP0riX_oGwMmKgDzdeCoSnrzw@mail.gmail.com |
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On Wed, Sep 27, 2017 at 1:40 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> I don't think you can even measure the overhead of building the
> table. This is inserting ~8k rows in an accurately sized hashtable - a
> vanishingly small amount of time in comparison to the backend startup
> time (and even more so postmaster startup). My measurement shows it
> takes about 0.4 ms to build (gdb in, query, reset oid2builtins = 0,
> query - repeat a couple times).
0.4ms isn't negligible as a fraction of backend startup time, is it?
I think backend startup time is a few milliseconds.
$ echo '\set x 1' > x.txt
$ pgbench -n -C -c 1 -f x.txt -T 10
transaction type: x.txt
scaling factor: 1
query mode: simple
number of clients: 1
number of threads: 1
duration: 10 s
number of transactions actually processed: 5091
latency average = 1.965 ms
tps = 508.866931 (including connections establishing)
tps = 12909.303693 (excluding connections establishing)
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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