Re: foreign key constraint, planner ignore index. - Mailing list pgsql-general

Andrew Nesheret wrote:
> Richard Huxton wrote:
>> Andrew Nesheret wrote:
>>> Richard Huxton wrote:
>>>> If you PREPARE .... then EXECUTE the same query, does it still use
>>>> the index?
> Tested, comments?
>
> --- code -----
>
> --- result ---
> Result for node #2007
>  Index Scan using fki_nodes on sf_ipv4traffic x  (cost=0.00..9.65 rows=1
> width=6) (actual time=0.060..0.060 rows=0 loops=1)
>    Index Cond: ($1 = node)
>  Total runtime: 0.131 ms
> Result for node #156
>  Seq Scan on sf_ipv4traffic x  (cost=0.00..360281.29 rows=15795383
> width=6) (actual time=0.048..108939.142 rows=15795376 loops=1)
>    Filter: ($1 = node)
>  Total runtime: 365989.953 ms

Since you are getting different plans, this can't be a planned query.
Just try feeding a text-file with some SQL PREPARE/EXECUTEs to psql -
you can  EXPLAIN ANALYSE EXECUTE ...


--
   Richard Huxton
   Archonet Ltd