Joel Jacobson <joel@gluefinance.com> wrote:
> I applied all the changes on 9.0beta manually and then it compiled without
> any assertion failures.
>
> I also changed the oids to a different unused range, since the ones I used
> before had been taken in 9.0beta1.
Thanks, but you still need to test your patch:
- You need to check your patch with "make check", because it requires adjustments in "rule" test; Your
pg_stat_transaction_functionis the longest name in the system catalog.
- You need to configure postgres with --enable-cassert to enable internal varidations. The attached test case failed
withthe following TRAP.
TRAP: FailedAssertion("!(entry->trans == ((void *)0))", File: "pgstat.c", Line: 715)
TRAP: FailedAssertion("!(tabstat->trans == trans)", File: "pgstat.c", Line: 1758)
> I suspect it is because get_tabstat_entry for some reason returns NULL, in
> for example pg_stat_get_transaction_tuples_inserted(PG_FUNCTION_ARGS).
>
> Does the function look valid? If you can find the error in it, the other
> functions probably have the same problem.
For the above trap, we can see the comment: /* Shouldn't have any pending transaction-dependent counts */
We don't expect to read stats entries during transactions. I'm not sure
whether accessing transitional stats during transaction is safe or not.
We might need to go other directions, for example: - Use "session stats" instead "transaction stats". You can see the
same information in difference of counters between before and after the transaction. - Export pgBufferUsage instead
ofrelation counters. They are buffer counters for all relations, but we can obviously export them because they are
justplain variables.
Regards,
---
Takahiro Itagaki
NTT Open Source Software Center