[Pgpool-general] EXPLAIN statement fails on 'kind mismatch'

[Tatsuo Ishii]

> >> hello
> >>
> >> after 2 weeks pgpool-II (2.25) was working good,
> >> I now have:
> >> 'kind mismatch among backends. Possible last query was: "EXPLAIN SELECT
> >> *
> >> FROM ycore.transfer_record WHERE
> >> transfer_record_id>400" kind details are: 0[D] 1[C]'
> >>
> >> just when we wanted to move to production.
> >>
> >> all other things still work, also 'EXPLAIN' on other tables,
> >> (also same query on this table worked until now)
> >> I have full logs of pgpool + 2 postgres backends
> >> how can I find out whats wrong ?
> >
> > Can you show me the outputs of EXPAIN which are executed directly on
> > postgres backends? My bet is, there are dead tuples difference between
> > backends which cause execution plan differences.
> > --
> > Tatsuo Ishii
> > SRA OSS, Inc. Japan
> >
> 
> backend 0:
> 
> explain select * from ycore.transfer_record where transfer_record_id > 400;
>                                        QUERY PLAN
> -----------------------------------------------------------------------------------------
>  Bitmap Heap Scan on transfer_record  (cost=4.60..20.16 rows=45 width=356)
>    Recheck Cond: (transfer_record_id > 400)
>    ->  Bitmap Index Scan on idx_tr_transfer_record_id  (cost=0.00..4.59
> rows=45 width=0)
>          Index Cond: (transfer_record_id > 400)
> (4 rows)
> 
> 
> backend 1:
> 
> explain select * from ycore.transfer_record where transfer_record_id > 400;
>                             QUERY PLAN
> -------------------------------------------------------------------
>  Seq Scan on transfer_record  (cost=0.00..24.48 rows=49 width=331)
>    Filter: (transfer_record_id > 400)
> (2 rows)
> 
> 
> 
> I can see there is a difference, but i don't know how to check what caused
> it, and how to avoid it next time.

Please make sure that you have idx_tr_transfer_record_id index on
backend 1. If you already have, please try vacuum analyze on the
database directly on backend 1.
--
Tatsuo Ishii
SRA OSS, Inc. Japan