recovery_target_xid & crashes on the master

Hi

I'm currently working on splitting StartupXLog into smaller
parts, because I need to reuse some of the parts for concurrent
wal recovery (for my GSoC project)

The function recoveryStopsHere in xlog.c checks if we should
stop recovery due to the values of recovery_target_xid and
recovery_target_time. For recovery_target_xid, we stop if
we see a commit or abort record for the given xid.

Now I wonder what happens if an (admittely rather confused) DBA
uses an xid of a transaction that was aborted because of a
crash of the master as recovery_target_xid. The way I read the
code, postgres will just recover until it reaches the end of
the xlog in that case because neither an COMMIT nor an ABORT
for that xid exists in the WAL.

I'm not sure if this is worth fixing - it seems like a rather
contrived corner case - but I though I'd bring it up...

greetings, Florian Pflug

Florian G. Pflug wrote:
> Hi
>
> I'm currently working on splitting StartupXLog into smaller
> parts, because I need to reuse some of the parts for concurrent
> wal recovery (for my GSoC project)
>
> The function recoveryStopsHere in xlog.c checks if we should
> stop recovery due to the values of recovery_target_xid and
> recovery_target_time. For recovery_target_xid, we stop if
> we see a commit or abort record for the given xid.
>
> Now I wonder what happens if an (admittely rather confused) DBA
> uses an xid of a transaction that was aborted because of a
> crash of the master as recovery_target_xid. The way I read the
> code, postgres will just recover until it reaches the end of
> the xlog in that case because neither an COMMIT nor an ABORT
> for that xid exists in the WAL.
>
> I'm not sure if this is worth fixing - it seems like a rather
> contrived corner case - but I though I'd bring it up...

I think you meant to send that to pgsql-hackers, not pgadmin-hackers...

//Magnus

Magnus Hagander wrote:
<snipped my mail>

> I think you meant to send that to pgsql-hackers, not pgadmin-hackers...
Ups - sorry for the noise. One shouldn't rely on thunderbird's
address autocompletion to read one's thoughts ;-)

greetings, Florian Pflug