|From:||Itagaki Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>|
|To:||Euler Taveira de Oliveira <euler(at)timbira(dot)com>|
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Euler Taveira de Oliveira <euler(at)timbira(dot)com> wrote:
> The functionality is divided in two parts. The first part is a hook in the
> utility module. The idea is capture the commands that doesn't pass through
> executor. I'm afraid that that hook will be used only for capturing non-DML
> queries. If so, why don't we hack the tcop/postgres.c and grab those queries
> from the same point we log statements?
DDLs can be used from user defined functions. It has the same reason
why we have executor hooks instead of tcop hooks.
> The second part is to use that hook to capture non-DML commands for
> pg_stat_statements module.
- I fixed a bug that it should handle only isTopLevel command.
- A new parameter pg_stat_statements.track_ddl (boolean) is
added to enable or disable the feature.
> Do we need to have rows = 0 for non-DML commands?
> Maybe NULL could be an appropriate value.
Yes, but it requires additional management to handle 0 and NULL
separately. I don't think it is worth doing.
> The PREPARE command stopped to count
> the number of rows. Should we count the rows in EXECUTE command or in the
> PREPARE command?
It requires major rewrites of EXECUTE command to pass the number of
affected rows to caller. I doubt it is worth fixing because almost all
drivers use protocol-level prepared statements instead of PREPARE+EXECUTE.
> The other command that doesn't count properly is COPY. Could
> you fix that?
I added codes for it.
> I'm concerned about storing some commands that expose passwords
> like CREATE ROLE foo PASSWORD 'secret'; I know that the queries are only
> showed to superusers but maybe we should add this information to documentation
> or provide a mechanism to exclude those commands.
I think there is no additonal problem there because we can see the 'secret'
command using pg_stat_activity even now.
> I don't know if it is worth the trouble adding some code to capture VACUUM and
> ANALYZE commands called inside autovacuum.
I'd like to exclude VACUUM and ANALYZE by autovacuum because
pg_stat_statements should not filled with those commands.
NTT Open Source Software Center
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