Re: Enable pg_stat_statements extension for limited statements only

Sayyid Ali Sajjad Rizavi <sasrizavi@gmail.com> writes:
> Hi, I'd like to propose a change and get advice if I should work on it.
> The extension pg_stat_statements is very helpful, but the downside is that
> it will take up too much disk space when storing query stats if it's
> enabled for all statements like SELECT, INSERT, UPDATE, DELETE.

It will only take up a lot of disk space if you let it, by setting
the pg_stat_statements.max parameter too high.

> For example, deletes do not happen too frequently; so I'd like to be able
> to enable pg_stat_statements only for the DELETE statement, maybe using
> some flags.

I'm a little skeptical of the value of that.  Why would you want stats
only for infrequent statements?

I'm not denying that there might be usefulness in filtering what
pg_stat_statements will track, but it's not clear to me that
this particular proposal will be useful to many people.

I wonder whether there would be more use in filters expressed
as regular expressions to match against the statement text.
That would allow, for example, tracking statements that mention
a particular table as well as statements with a particular
head keyword.  I could see usefulness in both a positive filter
(must match this to get tracked) and a negative one (must not
match this to get tracked).

            regards, tom lane