Re: vacuum error "left link changed unexpectedly"

Hi Tom,

I did run vacuum verbose".

INFO: vacuuming "public.userclick"
INFO: index "userclick_i01" now contains 13715747 row versions in 60640
pages
DETAIL: 0 index row versions were removed.
14209 index pages have been deleted, 14209 are currently reusable.
CPU 2.46s/6.06u sec elapsed 186.45 sec.
ERROR: left link changed unexpectedly

To me this looks as the index userclick_i01 is corrupted.
I can not recompile PG, this is a production system. Is there anything
else I could do to find out which file is affected?

Ulrich

Lane wrote:
> Ulrich Wisser <ulrich(dot)wisser(at)relevanttraffic(dot)se> writes:
>
>>vacuumdb: vacuuming of database "CLIX2" failed: ERROR: left link
>>changed unexpectedly
>
>
> Hm, is this repeatable? When I wrote the code I thought it was
> a can't-happen case, which is why the error message is so terse
> (it was only pure paranoia that made me put in the check at all).
> I suppose it must indicate a corrupted index, but I'm not clear
> on exactly what the nature of the corruption is.
>
> You might proceed by fixing the error message to be a little more
> helpful, say
>
> if (opaque->btpo_prev != leftsib)
> elog(ERROR, "left link changed unexpectedly in block %u of index %s",
> target, RelationGetRelationName(rel));
>
> (this is in src/backend/access/nbtree/nbtpage.c, about line 863 in
> current sources). Once you know which index has the problem,
> I would like to see the output of pg_filedump on that index.
> After you've got the dump, a REINDEX should fix it.
>
> BTW, which Postgres version is this exactly?
>
> regards, tom lane

--
Ulrich Wisser / System Developer

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