Re: Regression tests fail once XID counter exceeds 2 billion

On Sun, Nov 13, 2011 at 11:16 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> While investigating bug #6291 I was somewhat surprised to discover
> $SUBJECT.  The cause turns out to be this kluge in alter_table.sql:
>
>        select virtualtransaction
>        from pg_locks
>        where transactionid = txid_current()::integer

...

> that plasters on the appropriate epoch value for an
> assumed-to-be-current-or-recent xid, and returns something that squares
> with the txid_snapshot functions.  Then the test could be coded without
> kluges as

That fixes the test, but it doesn't fix the unreasonability of this situation.

We need a function called transactionid_current() so a normal user can write

select virtualtransaction
from pg_locks
where transactionid = transactionid_current()

and have it "just work".

We need a function whose behaviour matches xid columns in pg_locks and
elsewhere and that doesn't need to have anything to do with txid
datatype.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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