| From: | "Rigmor Ukuhe" <rigmor(dot)ukuhe(at)finestmedia(dot)com> |
|---|---|
| To: | <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Index problem |
| Date: | 2003-09-24 10:09:37 |
| Message-ID: | OEEHLFAIJHHMABJPIANIKEMACFAA.rigmor.ukuhe@finestmedia.com |
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| Thread: | |
| Lists: | pgsql-performance |
Hi,
I have a table containing columns:
"END_DATE" timestamptz NOT NULL
"REO_ID" int4 NOT NULL
and i am indexed "REO_ID" coulumn.
I have a query:
select "REO_ID", "END_DATE" from "PRIORITY_STATISTICS" where "REO_ID" IN
('112851' ,'112859' ,'112871' ,'112883' ,'112891' ,'112904' ,'112915'
,'112924' ,'112939' ,'112947' ,'112960' ,'112984' ,'112999' ,'113013'
,'113032' ,'113059' ,'113067' ,'113084' ,'113096' ,'113103' ,'113110'
,'113117' ,'113125' ,'113132' ,'113139' ,'113146' ,'113153' ,'113160'
,'113167' ,'113174' ,'113181' ,'113188' ,'113195' ,'113204' ,'113268'
,'113279' ,'113294' ,'113302' ,'113317' ,'113340' ,'113358' ,'113385'
,'113404' ,'113412' ,'113419' ,'113429' ,'113436' ,'113443' ,'113571'
,'113636' ,'113649' ,'113689' ,'113705' ,'113744' ,'113755' ,'113724'
,'113737' ,'113812' ,'113828' ,'113762' ,'113842' ,'113869' ,'113925'
,'113976' ,'114035' ,'114044' ,'114057' ,'114070' ,'114084' ,'114094'
,'114119' )
and it is _not_ using that index
But following query (notice there are less id-s in WHERE clause, but rest is
same)
select "REO_ID", "END_DATE" from "PRIORITY_STATISTICS" where "REO_ID" IN
('112851' ,'112859' ,'112871' ,'112883' ,'112891' ,'112904' ,'112915'
,'112924' ,'112939' ,'112947' ,'112960' ,'112984' ,'112999' ,'113013'
,'113032' ,'113059' ,'113067' ,'113084' ,'113096' ,'113103' ,'113110'
,'113117' ,'113125' ,'113132' ,'113139' ,'113146' ,'113153' ,'113160'
,'113167' ,'113174' ,'113181' ,'113188' ,'113195' ,'113204' ,'113268'
,'113279' ,'113294' ,'113302' ,'113317' ,'113340' ,'113358' ,'113385'
,'113404' ,'113412' ,'113419' ,'113429' ,'113436' ,'113443' ,'113571'
,'113636' ,'113649' ,'113689' ,'113705' ,'113744' ,'113755' ,'113724'
,'113737' )
will _is_ using index:
Index Scan using PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id, PRIORITY_STATISTICS_reo_id,
PRIORITY_STATISTICS_reo_id on PRIORITY_STATISTICS (cost=0.00..394.06
rows=102 width=12)
What causes this behaviour? is there any workaround? Suggestions?
best,
Rigmor Ukuhe
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