Horton

Re: New GUC to sample log queries

Adrien NAYRAT <adrien.nayrat@anayrat.info>

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From: Adrien Nayrat <adrien.nayrat@anayrat.info>
To: Dmitry Dolgov <9erthalion6@gmail.com>, Vik Fearing <vik.fearing@2ndquadrant.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Michael Paquier <michael@paquier.xyz>, <david.rowley@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-11-18T09:52:42Z
Lists: pgsql-hackers 
On 11/18/18 12:47 AM, Dmitry Dolgov wrote:
> This patch went through last few commitfests without any activity, but cfbot
> says it still applies and doesn't break any tests. From what I see there was
> some agreement about naming, so the patch is indeed needs more review. Could
> anyone from the reviewers (Vik?) confirm that it's in a good shape?

Thanks Dmitry to bringing this up.

For me, the question is how to name this GUC?
Is "log_sample_rate" is enough? I am not sure because it is only related to
queries logged by log_min_duration_statements.

Alors, I wonder if we should use the same logic for other parameters, such as
log_statement_stats
log_parser_stats
log_planner_stats
log_executor_stats

It was mentioned in this thread
https://www.postgresql.org/message-id/20180710183828.GB3890%40telsasoft.com

Commits

  1. Use pg_strong_random() to select each server process's random seed.

  2. Use a separate random seed for SQL random()/setseed() functions.

  3. Marginal performance hacking in erand48.c.

  4. Fix latent problem with pg_jrand48().

  5. Silence compiler warning

  6. Add log_statement_sample_rate parameter