From: | Reynard Hilman <reynardmh(at)lightsky(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | index not being used |
Date: | 2002-12-14 20:43:37 |
Message-ID: | 3DFB97F9.8050801@lightsky.com |
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Lists: | pgsql-general |
I'm having problem where index is not being used in query on very big
table (10 million rows), even after I set the enable_seqscan=off and
enable_indexscan=on. The query always choose seq scan when I do EXPLAIN.
This causes the query to take about 25 seconds to execute.
However, if the table only has 1 million rows, the query chooses the
index scan and only take about 80 msec.
here is the table structure:
create table test_10million (
id int8,
app_id int8
);
< fill the table with 10 million record >
create index test_10million_id on test_10million (id);
this query always uses sequential scan:
select * from test_10million where id = 123 and app_id = 100;
Does the number of rows matter here? (is 10 million too big for the
index table?).
thanks,
- reynard
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