Re: proposal - log_full_scan

On Sat, Apr 17, 2021 at 05:22:59PM +0200, Pavel Stehule wrote:
> 
> The fullscan of this table needs about 30ms and has 200K rows. So
> decreasing log_min_duration to this value is very risky.
> 
> [...]
> 
> I use  pg_stat_all_tables.seq_scan and I see seq scans there. But I need to
> know the related queries.

Maybe you could use pg_qualstats ([1]) for that?  It will give you the list of
quals (with the underlying queryid) with a tag to specify if they were executed
as an index scan or a sequential scan.  It wouldn't detect queries doing
sequential scan that don't have any qual for the underlying relations, but
those shouldn't be a concern in your use case.

If you setup some sampling, the overhead should be minimal.

[1]: https://github.com/powa-team/pg_qualstats/