Re: xmin increasing within a transaction block?

Hi,

On 2017-11-06 10:36:06 +0100, Luca Ferrari wrote:
> Hi all,
> I suspect this has a trivial explaination, but this is what I'm experiencing:
>
> > CREATE TABLE foo( i int );
> > BEGIN;
> * > INSERT INTO foo(i) VALUES( 1 );
> * > INSERT INTO foo(i) VALUES( 2 );
> * > SELECT xmin, cmin, xmax, cmax, i FROM foo;
> xmin | cmin | xmax | cmax | i
> ------+------+------+------+---
> 2466 | 0 | 0 | 0 | 1
> 2467 | 1 | 0 | 1 | 2
> (2 rows)
>
> * > SELECT txid_current();
> txid_current
> --------------
> 2465
> (1 row)
>
>
> Why is xmin greater than the current transaction id (and most notably
> not "fixed")?
> What am I missing here?
> I'm running 9.6.5.

That doesn't look like plain postgres behaviour to me. Any chance you're
using a pooler in statement mode in front of postgres?

Greetings,

Andres Freund