Re: BUG #14889: explain analyze is taking much more time than actual execution

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, mahmoud alorfaly <mahmoud(dot)alorfaly(at)gmail(dot)com>, PostgreSQL mailing lists <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: BUG #14889: explain analyze is taking much more time than actual execution
Date: 2017-11-06 21:20:39
Message-ID: CAEepm=0OFFHRkDUYzdHFPpQeki6b5U59PjOF7KW17PseH4vSCA@mail.gmail.com
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On Tue, Nov 7, 2017 at 3:43 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> The size of the overhead in this case implies that gettimeofday() is doing
> a kernel call, which I wouldn't really have expected on any modern Linux
> kernel. What hardware is this on? Is there virtualization involved?

A virtual server with no vDSO, I'll bet. Like this:

https://stackoverflow.com/questions/42622427/gettimeofday-not-using-vdso

--
Thomas Munro
http://www.enterprisedb.com

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