On Thu, Jun 16, 2016 at 01:56:44PM -0500, Kevin Grittner wrote:
> On Thu, Jun 16, 2016 at 1:32 PM, Andres Freund <andres@anarazel.de> wrote:
>
> > With old_snapshot_threshold=1 I indeed can reproduce the issue. I
> > disabled autovacuum, to make the scheduling more predictable. But it
> > should "work" just as well with autovacuum.
> >
> > S1: CREATE TABLE toasted(largecol text);
> > INSERT INTO toasted SELECT string_agg(random()::text, '-') FROM generate_series(1, 10000000);
> > BEGIN;
> > DELETE FROM toasted;
> > S2: BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
> > S2: SELECT hashtext(largecol), length(largecol) FROM toasted;
> >> ...
> > S1: COMMIT;
> > S2: SELECT hashtext(largecol), length(largecol) FROM toasted;
> >> ...
> > S1: /* wait for snapshot threshold to be passed */
> > S1: VACUUM pg_toast.pg_toast_16437;
> >> INFO: 00000: "pg_toast_16437": found 61942 removable, 0 nonremovable row versions in 15486 out of 15486 pages
> >> DETAIL: 0 dead row versions cannot be removed yet.
> > S2: SELECT hashtext(largecol), length(largecol) FROM toasted;
> > ERROR: XX000: missing chunk number 0 for toast value 16455 in pg_toast_16437
> > LOCATION: toast_fetch_datum, tuptoaster.c:1945
>
> Thanks! That's something I should be able to work with.
> Unfortunately, I am going to be on vacation, so I won't have any
> results until sometime after 28 June.
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