Re: IRe: BUG #16792: silent corruption of GIN index resulting in SELECTs returning non-matching rows

On 22/07/2021 12:07, Pawel Kudzia wrote:
> On Thu, Jul 22, 2021 at 9:25 AM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>>
>> Fixed those bugs, new patch version attached. Pawel, can you test this
>> again, please? At this point, I'm pretty sure this isn't going to reveal
>> any more information about the original problem, but at least we're
>> ironing out bugs from the 'amcheck' patch..
>
> thank you for the next patch Heikki!
> no crash this time! i'm sending a message in a separate mail since i'm
> not sure if it'll pass through attachment size limit that's applied
> for the list.

Thanks! So looking at the log, amcheck is not reporting any more problems.

>> I'm grasping at straws here, but here's one more thing we could try: the
>> query returned these incorrect tuples:
>>
>> ctid | entity_id
>> --------------+-----------
>> (4002784,1) | 38048120
>> (4002869,14) | 95333744
>> (2 rows)
>>
>> We know those entries are in the GIN index with key '1373', when they
>> shouldn't be. But I wonder if the correct keys for those tuples are
>> present? Pawel, can you try this, please:
>
> [queries with nore rows returned]

Ok, so the index is missing entries for the correct key. Looks like the
index entries were inserted into the wrong subtree, under wrong key. But
*how* did that happen? I'm out of ideas, I'm afraid :-(.

- Heikki