> On Wed, 7 May 2014 09:38:16 +0300, "Vlad Khorsun" wrote:
>>> This leads me to the questions:
>>> 1) When are prepared or rolled back transactions removed from
>>> RDB$TRANSACTIONS? Or are they kept indefinitely?
>>
>> Its never removed. And i see no problem with it.
I was a bit wrong - when distributed transaction is *committed* by
connection
which started it *and* if there was provided information about all participants
(i.e.
there is description record) - in this case engine automatically deletes record
in
RDB$TRANSACTION.
In other cases (rollback by original connection, no description or
commit\rollback
after reconnect) - record is not deleted. I think it is necessary to allow
transaction
manager to handle local sub-transaction again, if necessary (if recover attempt
failed
at another node, for example)
> I assume it doesn't survive a backup/restore cycle, otherwise we have a
> problem with duplicate transaction ids ;)
Exactly :)
>>> 2) Is there an alternative to removing this information?
>>
>> I see no big need to clean up RDB$TRANSACTIONS. If we really want,
> we
>> can
>> make sweep to take care about it - to delete entires which is older than
>> new OIT.
>> But again, i see no real needs to do it.
>
> I am trying to understand why Jaybird deletes the entry. It looks like it
> is doing it, because in a recovery situation it retrieves *all*
> transactions listed in RDB$TRANSACTIONS and iterates over it to match the
> Xid used on prepare to find the right transaction id. This works fine when
> the number of transactions is small, but is probably not a good idea when
> there is a large number of transactions.
gfix lists in-limbo transactions using isc_database_info('isc_info_limbo')
call.
It doesn't query RDB$TRANSACTIONS for the list, only for the descriptions.
Regards,
Vlad
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