Horton

Re: New GUC to sample log queries

Adrien NAYRAT <adrien.nayrat@anayrat.info>

View thread View on postgr.es
From: Adrien NAYRAT <adrien.nayrat@anayrat.info>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Dmitry Dolgov <9erthalion6@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, <vik.fearing@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, "Michael Paquier" <michael@paquier.xyz>, David Rowley <david.rowley@2ndquadrant.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-11-30T08:46:57Z
Lists: pgsql-hackers 
On 11/29/18 10:48 PM, Alvaro Herrera wrote:
> Thanks!  I pushed this with two changes -- one was to reword the docs a
> bit more, and the other was to compute in_sample only if it's going to
> be used (when exceeded is true).  I hope this won't upset any compilers ...

Thanks!

> 
> I wonder if there's any sensible way to verify the behavior in an
> automated fashion.  Who know what marvels we'd discover about the
> reliability/uniformity of random() across platforms.
> 

Yes, I also wondered how to add tests.

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