--- Vida Luz <vlal@ideay.net.ni> escribió:
> Hi all
>
> I have a table in y database that have 8,000,000 of
> rows, when I execut a
> query on this table, the answuer is very slow.
>
> I have a index in this table by datem, my table is
>
> Column | Type | Modifiers
> ---------+---------------------------+-----------
> nombre | character varying(15) |
> mensaje | character varying(250) |
> nombre_env | character varying(100) |
> cel_env | character varying(15) |
> fecha | date |
> hora | time(0) without time zone |
> Indexes: correo_fecha
>
> Myindex is:
> Index "correo_fecha"
> Column | Type
> --------+------
> fecha | date
> btree
>
> My query is
>
> select EXTRACT(MONTH FROM M.fecha) as ho,count(*) as
> tot from correo M
> where EXTRACT(YEAR FROM M.fecha)='2004' group by
> EXTRACT(MONTH FROM
> M.fecha);
>
> When I executed a EXPLAIN ANALIZE, I hace the
> following Answer
>
> Aggregate (cost=122439.31..122558.36 rows=2381
> width=4) (actual
> time=64626.46..76021.93 rows=11 loops=1)
> -> Group (cost=122439.31..122498.84 rows=23809
> width=4) (actual
> time=63951.10..73332.27 rows=4177209 loops=1)
> -> Sort (cost=122439.31..122439.31
> rows=23809 width=4) (actual
> time=63951.09..67240.94 rows=4177209 loops=1)
> -> Seq Scan on web_sms m
> (cost=0.00..120708.48 rows=23809
> width=4) (actual time=0.30..55077.31 rows=4177209
> loops=1)
> Total runtime: 76069.22 msec
>
> How can I do to acceletate the answer?
>
> Thanks.
>
Maybe this question should be done at the PERFORMANCE
list.
What about creating the index on the extract
expresion?
CREATE INDEX tuIndice ON correo (date_part('year',
fecha));
I found the other way i suggested in the spanish list
is not correct (sintax) but this way it works (i have
proved it).
regards,
Jaime Casanova
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