Re: Query Optimization

Sorry for the noise.
I make vacuum analyze and the problem is solved.
Kaloyan Iliev

Kaloyan Iliev Iliev wrote:
> Hi,
> Can anyone suggest why this query so slow.
>
> SELECT version();
>                                                version
> ---------------------------------------------------------------------------------------------------------
>
> PostgreSQL 8.4.2 on i386-portbld-freebsd7.2, compiled by GCC cc (GCC)
> 4.2.1 20070719  [FreeBSD], 32-bit
> (1 row)
> explain analyze SELECT  DT.value,
>                        DT.meassure_date,
>                        DT.ms_status_id as status_id,
>                        S.descr_bg as status_bg,
>                        S.descr_en as status_en,
>                        VT.id as value_type_id,
>                        VT.descr_en as value_type_en,
>                        VT.descr_bg as value_type_bg,
>                        T.unit as value_type_unit,
>                        T.name as general_value_type,
>                        T.ms_db_type_id
>                FROM
>                    ms_data AS DT,
>                    ms_statuses AS S,
>                    ms_value_types AS VT,
>                    ms_types AS T,
>                    ms_commands_history AS CH
>               WHERE  DT.ms_value_type_id = 88  AND
>                      DT.meassure_date >= '2010-04-01 1:00:00' AND
>                      DT.meassure_date <= '2010-04-01 1:10:00' AND
>                      DT.ms_command_history_id = CH.id AND
>                      CH.ms_device_id = 7 AND
>                      DT.ms_value_type_id = VT.id AND
>                      VT.ms_type_id = T.id AND
>                      DT.ms_status_id = S.id
>               GROUP BY value,
>                        meassure_date,
>                        status_id,
>                        status_bg,
>                        status_en,
>                        value_type_id,
>                        value_type_en,
>                        value_type_bg,
>                        value_type_unit,
>                        general_value_type,
>                        ms_db_type_id
>               ORDER BY meassure_date DESC;
>                  QUERY PLAN
>
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

>
> Group  (cost=23.93..23.96 rows=1 width=229) (actual
> time=63274.021..63274.021 rows=0
> loops=1)
> ->  Sort  (cost=23.93..23.94 rows=1 width=229) (actual
> time=63274.016..63274.016 rows=0 loops=1)
>    Sort Key: dt.meassure_date, dt.value, dt.ms_status_id, s.descr_bg,
> s.descr_en, vt.id, vt.descr_en, vt.descr_bg, t.unit, t.name,
> t.ms_db_type_id               Sort Method:  quicksort  Memory: 17kB
>        ->  Nested Loop  (cost=0.00..23.92 rows=1 width=229) (actual
> time=63273.982..63273.982 rows=0
> loops=1)
>            ->  Nested Loop  (cost=0.00..19.64 rows=1 width=165)
> (actual time=63273.977..63273.977 rows=0
> loops=1)
>                ->  Nested Loop  (cost=0.00..15.36 rows=1 width=101)
> (actual time=63273.974..63273.974 rows=0
> loops=1)
>                    ->  Nested Loop  (cost=0.00..11.08 rows=1 width=23)
> (actual time=63273.970..63273.970 rows=0
> loops=1)
>                        ->  Index Scan using
> ms_commands_history_ms_device_id_idx on ms_commands_history ch
> (cost=0.00..4.33 rows=1 width=8) (actual time=0.163..25254.004
> rows=9807 loops=1)
>                                      Index Cond: (ms_device_id = 7)
>                                ->  Index Scan using
> ms_data_ms_command_history_id_idx on ms_data dt  (cost=0.00..6.74
> rows=1 width=31) (actual time=3.868..3.868 rows=0 loops=9807)
>                                      Index Cond:
> (dt.ms_command_history_id = ch.id)
>                                      Filter: ((dt.meassure_date >=
> '2010-04-01 01:00:00'::timestamp without time zone) AND
> (dt.meassure_date <= '2010-04-01 01:10:00'::timestamp without time
> zone) AND (dt.ms_value_type_id = 88))
>                          ->  Index Scan using ms_value_types_pkey on
> ms_value_types vt  (cost=0.00..4.27 rows=1 width=82) (never
> executed)                                                 Index Cond:
> (vt.id = 88)
>                    ->  Index Scan using ms_types_pkey on ms_types t
> (cost=0.00..4.27 rows=1 width=72) (never
> executed)
> Index Cond: (t.id = vt.ms_type_id)
>              ->  Index Scan using ms_statuses_pkey on ms_statuses s
> (cost=0.00..4.27 rows=1 width=68) (never
> executed)                                                        Index
> Cond: (s.id = dt.ms_status_id)
> Total runtime: 63274.256 ms
> Thanks in advance.
>
> Kaloyan Iliev
>