Horton

Re: New GUC to sample log queries

Dmitry Dolgov <9erthalion6@gmail.com>

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From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: adrien.nayrat@anayrat.info, Vik Fearing <vik.fearing@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Michael Paquier <michael@paquier.xyz>, david.rowley@2ndquadrant.com, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-11-19T13:52:05Z
Lists: pgsql-hackers 
> On Mon, Nov 19, 2018 at 2:40 PM Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>
> On 11/19/18 2:57 AM, Michael Paquier wrote:
> > On Sun, Nov 18, 2018 at 12:18:33PM +0100, Dmitry Dolgov wrote:
> >> Since it's hard to come up with a concise name that will mention sampling rate
> >> in the context of min_duration_statement, I think it's fine to name this
> >> configuration "log_sample_rate", as long as it's dependency from
> >> log_min_duration_statements is clearly explained in the documentation.
> >
> > log_sample_rate looks fine to me as a name.
>
> That seems far too short to me - the name should indicate it applies to
> statement logging. I'd say log_statement_sample_rate is better.

I agree, sounds reasonable.

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