Horton

Re: New function pg_stat_statements_reset_query() to reset statistics of a specific query

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: sk@zsrv.org
Cc: vik.fearing@2ndquadrant.com, Haribabu Kommi <kommi.haribabu@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Magnus Hagander <magnus@hagander.net>, Robert Haas <robertmhaas@gmail.com>, Fujii Masao <masao.fujii@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Euler Taveira <euler@timbira.com.br>, pgsql-hackers <pgsql-hackers@postgresql.org>, Simon Riggs <simon@2ndquadrant.com>, Dave Page <dpage@pgadmin.org>
Date: 2018-11-28T12:36:30Z
Lists: pgsql-hackers 
On Wed, Nov 28, 2018 at 4:45 PM Sergei Kornilov <sk@zsrv.org> wrote:
>
> Hello
>
> > My preference is for NULL to mean *all* so this is my favorite option,
> > except that the first query should reset everything.
>
> I am +1 for this option. NULL treat as "any" and pg_stat_statements_reset(NULL,NULL,NULL) to reset everything
>

The problem with this idea is that if someone specifies a particular
parameter using query and the query doesn't return any parameters,
then it can lead to inadvertent behavior.  For example, if user uses
something like pg_stat_statements_reset(<valid_user_id>,
<valid_db_id>, SELECT s.queryid FROM pg_stat_statements AS s WHERE
s.query = 'SELECT $1 AS "ONE"');  now, if the query doesn't return any
row, we will remove the stats for all queries that belong to
(userid,dbid).  It could be surprising for some users, that's why we
came up with option-4 where we keep the default value of parameters as
0.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Extend pg_stat_statements_reset to reset statistics specific to a

  2. Default monitoring roles