Re: [GENERAL] OUTER JOIN IS SLOW

Yes, ANALYZE should definitely improve the performance for query...

--------------
Shoaib Mir
EnterpriseDB (www.enterprisedb.com)

On 12/24/06, Benjamin Arai <benjamin(at)araisoft(dot)com> wrote:
>
> Just to make things more clear I ran EXPLAIN ANALYZE on the slow query.
> I got
>
> Merge Full Join (cost=62.33..73.36 rows=1000 width=19) (actual
> time=39.205..8521.644 rows=272 loops=1)
> Merge Cond: ("outer".pkey = "inner".d1)
> -> Index Scan using mutualfd_weekday_qbid_pkey_idx on
> mutualfd_weekday_qbid (cost=0.00..6.01 rows=1 width=19) (actual
> time=34.579..8510.801 rows=253 loops=1)
> Index Cond: ((pkey >= '2005-12-15'::date) AND (pkey <=
> '2006-12-15'::date))
> Filter: (cusip = '92193920'::text)
> -> Sort (cost=62.33..64.83 rows=1000 width=4) (actual
> time=4.604..5.674 rows=262 loops=1)
> Sort Key: d1.d1
> -> Function Scan on "getDateRange" d1 (cost=0.00..12.50
> rows=1000 width=4) (actual time=2.591..3.591 rows=262 loops=1)
> Total runtime: 8522.894 ms
> (9 rows)
>
> It looks like this line:
>
> "-> Index Scan using mutualfd_weekday_qbid_pkey_idx on
> mutualfd_weekday_qbid (cost=0.00..6.01 rows=1 width=19) (actual
> time=34.579..8510.801 rows=253 loops=1)"
>
> is the problem. As I understand it is using the index but it is low as
> dirt. Hopefully, the -z will fix this. I also ran the same query but
> with earlier dates in the table and the query ran much faster.
>
> Merge Full Join (cost=3492.48..3505.60 rows=1034 width=19) (actual
> time=7.605..12.851 rows=273 loops=1)
> Merge Cond: ("outer".d1 = "inner".pkey)
> -> Sort (cost=62.33..64.83 rows=1000 width=4) (actual
> time=4.586..5.530 rows=263 loops=1)
> Sort Key: d1.d1
> -> Function Scan on "getDateRange" d1 (cost=0.00..12.50
> rows=1000 width=4) (actual time=2.493..3.515 rows=263 loops=1)
> -> Sort (cost=3430.15..3432.74 rows=1034 width=19) (actual
> time=2.998..3.971 rows=263 loops=1)
> Sort Key: mutualfd_weekday_qbid.pkey
> -> Index Scan using mutualfd_weekday_qbid_pkey on
> mutualfd_weekday_qbid (cost=0.00..3378.38 rows=1034 width=19) (actual
> time=0.075..1.843 rows=263 loops=1)
> Index Cond: ((cusip = '92193920'::text) AND (pkey >=
> '1999-12-15'::date) AND (pkey <= '2000-12-15'::date))
> Total runtime: 13.935 ms
> (10 rows)
>
> In this case it only took 13.935ms as compared to 8522.894 ms for the
> newer data.
>
> Benjamin
>
> Shoaib Mir wrote:
> > ....adding to the last email, for now try the work_mem but you should
> > be adding ANALYZE along with the VACUUM (with a cron job I guess) you
> > do regularly.
> >
> > ------------
> > Shoaib Mir
> > EntperpriseDB ( www.enterprisedb.com <http://www.enterprisedb.com>)
> >
> > On 12/24/06, *Shoaib Mir* <shoaibmir(at)gmail(dot)com
> > <mailto:shoaibmir(at)gmail(dot)com>> wrote:
> >
> > Try increasing the work_mem first to see the change, that might
> help.
> >
> > -------------
> > Shoaib Mir
> > EnterpriseDB ( www.enterprisedb.com <http://www.enterprisedb.com>)
> >
> > On 12/24/06, *Benjamin Arai* <benjamin(at)araisoft(dot)com
> > <mailto:benjamin(at)araisoft(dot)com>> wrote:
> >
> > I have been running pieces of my PL function by hand and I
> > have found
> > that the following queries work by themselves taking less than
> > a second
> > to execute.
> >
> > getDateRange"('12/1/2005','12/1/2006') <- simply generates a
> > date
> > list. Doesn't even access a table
> >
> > SELECT * FROM mutualfd_weekday_qbid WHERE cusip='92193920'
> > AND pkey >=
> > '12/15/2005' AND pkey <= '12/15/2006';
> >
> > But when combined as below it takes 10 seconds to execute.
> >
> > SELECT d1 as date, d2.data as data FROM
> > "getDateRange"('12/1/2005','12/1/2006') d1 FULL OUTER JOIN
> > (SELECT *
> > FROM mutualfd_weekday_qbid WHERE cusip='92193920' AND pkey >=
> > '12/15/2005' AND pkey <= '12/15/2006') d2 ON d1=d2.pkey;
> >
> > Do I need to increase the work_mem or is this possible still a
> > ANALYZE
> > issue?
> >
> > Benjamin
> >
> > ---------------------------(end of
> > broadcast)---------------------------
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