On 02.06.2025 19:25, Alexander Korotkov wrote:
On Tue, May 13, 2025 at 12:49 PM Alena Rybakina
<a.rybak...@postgrespro.ru> wrote:
On 12.05.2025 08:30, Amit Kapila wrote:
On Fri, May 9, 2025 at 5:34 PM Alena Rybakina <a.rybak...@postgrespro.ru> wrote:
I did a rebase and finished the part with storing statistics separately from
the relation statistics - now it is possible to disable the collection of
statistics for relationsh using gucs and
this allows us to solve the problem with the memory consumed.
I think this patch is trying to collect data similar to what we do for
pg_stat_statements for SQL statements. So, can't we follow a similar
idea such that these additional statistics will be collected once some
external module like pg_stat_statements is enabled? That module should
be responsible for accumulating and resetting the data, so we won't
have this memory consumption issue.
The idea is good, it will require one hook for the pgstat_report_vacuum
function, the extvac_stats_start and extvac_stats_end functions can be
run if the extension is loaded, so as not to add more hooks.
+1
Nice idea of a hook. Given the volume of the patch, it might be a
good idea to keep this as an extension.
Okay, I'll realize it and apply the patch)
But I see a problem here with tracking deleted objects for which
statistics are no longer needed. There are two solutions to this and I
don't like both of them, to be honest.
The first way is to add a background process that will go through the
table with saved statistics and check whether the relation or the
database are relevant now or not and if not, then
delete the vacuum statistics information for it. This may be
resource-intensive. The second way is to add hooks for deleting the
database and relationships (functions dropdb, index_drop,
heap_drop_with_catalog).
Can we workaround this with object_access_hook?
I think this could fix the problem. For the OAT-DROP access type, we can
call a function to reset the vacuum statistics for relations that are
about to be dropped.
At the moment, I don’t see any limitations to using this approach.
--
Regards,
Alena Rybakina
Postgres Professional
