"Mark Liberman" <[EMAIL PROTECTED]> wrote
>
> First run, after a night of inactivity:
>
> -> Bitmap Index Scan on 1min_events_file_id_begin_idx
> (cost=0.00..37.85 rows=3670 width=0) (actual time=313.468..313.468
> rows=11082
> loops=1)
> Index Cond: (file_id = 137271)
> Total runtime: 313.643 ms
>
> Second run, after that:
>
> -> Bitmap Index Scan on 1min_events_file_id_begin_idx
> (cost=0.00..37.85 rows=3670 width=0) (actual time=2.106..2.106 rows=11082
> loops=1)
> Index Cond: (file_id = 137271)
> Total runtime: 2.276 ms
It is clear that the first query takes longer time because of the IO time of
index 1min_events_file_id_begin_idx (see 313.468 vs. 2.106). I am afraid
currently there is no easy solution for this situation, unless you could
predicate which part of relation/index your query will use, then you can
preload or "warm-up" cache for it.
Regards,
Qingqing
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
