Re: Access to transaction status

"Christian Plattner" <postgresql(at)sioux(dot)ch> writes:
> From: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>> How much later? clog is not kept forever.

> ... Ofcourse one should not do a
> VACUUM FULL while not being sure about the status of a transaction in the
> past :)

As long as you haven't done a cluster-wide VACUUM, clog status will not
get recycled. For the application you're describing I think this will
work fine.

You might want to set up the API of the inquiry function to include
specified return codes for UNKNOWN (older than beginning of clog) and
FUTURE (greater than NextXid) as well as COMMITTED, ABORTED, and
INPROGRESS. The current implementation can't easily give you UNKNOWN
(it'll error out instead) but any general-usage function of this kind
would have to offer that.

regards, tom lane