Re: Sample rate added to pg_stat_statements

[Andrey M. Borodin]

> On 7 Jan 2025, at 16:05, Ilia Evdokimov <ilya.evdoki...@tantorlabs.com> wrote:
> 
>> 1. This code seems a little different from your patch. It is trying to avoid 
>> engaging PRNG. I'm not sure it's a good idea, but still. Also, it uses "<=", 
>> not "<".
>> 
>>     xact_is_sampled = log_xact_sample_rate != 0 &&
>> (log_xact_sample_rate == 1 ||
>> pg_prng_double(&pg_global_prng_state) <= log_xact_sample_rate);
>> 
> Are we sure we're discussing the same patch? Because these remarks refer to 
> the 5 version of the patch, which I abandoned due to your remarks.

Yes. v6 has this code
+       if (nesting_level == 0)
+               current_query_sampled = (pg_prng_double(&pg_global_prng_state) 
< pgss_sample_rate);

while upstream has code that I cited. And logic is slightly different.


Best regards, Andrey Borodin.