On Tue, Nov 26, 2019 at 3:26 PM [email protected] [firebird-support] <
[email protected]> wrote:
>
> I'm having a problem while running manually sweep, it's not increasing OIT
> as expected.
>
As you mentioned in your bug report, the problem was a transaction stuck in
limbo - the first half of a
two-phase commit. Sweep, quite rightly, doesn't clean up limbo
transactions.
> Just to explain better:
>
> I'm copying de DB as a backup, and I'm trying do sweep it, so I stopped
> Firebird, restarted, tried to sweep, stopped Fb again, tried to sweep with
> offline Fb server, tried gfix -mend, which found 3 warnings (0 fixed):
>
Sweep doesn't require stopping Firebird and stopping Firebird is going to
have no effect on
the transaction that's half way through a two-phase commit.
>
> backup Thu Nov 14 18:27:53 2019
> Database: /db/db_no_sweep.fdb
> Validation started
> Warning: Relation has 2 orphan backversions {0 in use} in table
> CONTAS_A_RECEBER (247)
> Warning: Relation has 3 orphan backversions {0 in use} in table
> NFE_LOTE_DADOS (253)
> Warning: Relation has 8 orphan backversions {0 in use} in table
> NF_SAIDA_CAPA (575)
>
Orphan back versions waste space but have no effect on the consistency of
the database. They
are created if Firebird is stopped during garbage collection. That
shouldn't happen, but neither
program or operating system crashes. When the garbage collector - thread
or cooperative -
finds old versions of a record that are no longer needed by any active
transaction it first sets
the back version pointer to zero in the oldest version of the record that
is needed. Then it
goes to the page that holds the back version and marks that space as free
and available for
reuse.
>
> backup Thu Nov 14 18:53:44 2019
> Database: /db/db_no_sweep.fdb
> Validation finished: 0 errors, 3 warnings, 0 fixed
>
> I've got no error, no warning at all, any ideas?
>
As you suggest elsewhere, Sweep with a verbose mode might report that
transaction xyzzy is stuck
in the middle of a two-phase commit. That would have saved you a lot of
looking
Good luck,
Ann
