Frequently Asked Questions (FAQ) for PostgreSQL
- Last updated: Sun Mar 3 11:02:16 EST 2002
+ Last updated: Sun Mar 3 13:35:39 EST 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
4.8) My queries are slow or don't make use of the indexes. Why?
Indexes are not automatically used by every query. Indexes are only
- used if the table is larger than a minimum size, and the index selects
+ used if the table is larger than a minimum size, and the query selects
only a small percentage of the rows in the table. This is because the
random disk access caused by an index scan is sometimes slower than a
straight read through the table, or sequential scan.
alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
- <P>Last updated: Sun Mar 3 11:02:16 EST 2002</P>
+ <P>Last updated: Sun Mar 3 13:35:39 EST 2002</P>
<P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
<H4><A name="4.8">4.8</A>) My queries are slow or don't make use of
the indexes. Why?</H4>
Indexes are not automatically used by every query. Indexes are only
- used if the table is larger than a minimum size, and the index
+ used if the table is larger than a minimum size, and the query
selects only a small percentage of the rows in the table. This is
because the random disk access caused by an index scan is sometimes
slower than a straight read through the table, or sequential scan.