From: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
Cc: | Julien Rouhaud <rjuju123(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: expose parallel leader in CSV and log_line_prefix |
Date: | 2020-07-10 16:55:25 |
Message-ID: | 20200710165524.GL26220@telsasoft.com |
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Lists: | pgsql-hackers |
On Fri, Jul 10, 2020 at 12:45:29PM -0400, Alvaro Herrera wrote:
> On 2020-Mar-18, Justin Pryzby wrote:
>
> > On Sun, Mar 15, 2020 at 12:49:33PM +0100, Julien Rouhaud wrote:
>
> > template1=# SET log_temp_files=0; explain analyze SELECT a,COUNT(1) FROM t a JOIN t b USING(a) GROUP BY 1;
> > 2020-03-15 21:20:47.288 CDT [5537 5537]LOG: statement: SET log_temp_files=0;
> > SET
> > 2020-03-15 21:20:47.289 CDT [5537 5537]LOG: statement: explain analyze SELECT a,COUNT(1) FROM t a JOIN t b USING(a) GROUP BY 1;
> > 2020-03-15 21:20:51.253 CDT [5627 5537]LOG: temporary file: path "base/pgsql_tmp/pgsql_tmp5627.0", size 6094848
> > 2020-03-15 21:20:51.253 CDT [5627 5537]STATEMENT: explain analyze SELECT a,COUNT(1) FROM t a JOIN t b USING(a) GROUP BY 1;
> > 2020-03-15 21:20:51.254 CDT [5626 5537]LOG: temporary file: path "base/pgsql_tmp/pgsql_tmp5626.0", size 6103040
> > 2020-03-15 21:20:51.254 CDT [5626 5537]STATEMENT: explain analyze SELECT a,COUNT(1) FROM t a JOIN t b USING(a) GROUP BY 1;
> > 2020-03-15 21:20:51.263 CDT [5537 5537]LOG: temporary file: path "base/pgsql_tmp/pgsql_tmp5537.1.sharedfileset/o15of16.p0.0", size 557056
>
> I think it's overly verbose; all non-parallel backends are going to get
> their own PID twice, and I'm not sure this is going to be great to
> parse. I think it would be more sensible that if the process does not
> have a parent (leader), %P expands to empty.
That's what's done.
+ <entry>Process ID of the parallel group leader if this process was
+ at some point involved in parallel query, otherwise null. For a
+ parallel group leader itself, this field is set to its own process
+ ID.</entry>
2020-07-10 11:53:32.304 CDT [16699 ]LOG: statement: SELECT 1;
2020-07-10 11:53:32.304 CDT,"pryzbyj","postgres",16699,"[local]",5f089d0b.413b,1,"idle",2020-07-10 11:53:31 CDT,3/4,0,LOG,00000,"statement: SELECT 1;",,,,,,,,,"psql","client backend",
--
Justin
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