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Update FAQ.
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doc/FAQ
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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL
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Frequently Asked Questions (FAQ) for PostgreSQL
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Last updated: Wed May 30 18:57:52 EDT 2001
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Last updated: Wed May 30 19:00:33 EDT 2001
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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@ -709,9 +709,9 @@ Maximum number of indexes on a table? unlimited
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column statistics on its own, so VACUUM ANALYZE must be run to collect
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column statistics on its own, so VACUUM ANALYZE must be run to collect
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them periodically.
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them periodically.
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Indexes are usually not used for ORDER BY or joins: a sequential scan
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Indexes are usually not used for ORDER BY or joins. A sequential scan
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followed by an explicit sort is faster than an indexscan of all tuples
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followed by an explicit sort is faster than an indexscan of all tuples
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of a large table, because it takes fewer disk accesses.
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of a large table. This is because random disk access is very slow.
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When using wild-card operators such as LIKE or ~, indices can only be
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When using wild-card operators such as LIKE or ~, indices can only be
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used if the beginning of the search is anchored to the start of the
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used if the beginning of the search is anchored to the start of the
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alink="#0000FF">
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alink="#0000FF">
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
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<P>Last updated: Wed May 30 18:57:52 EDT 2001</P>
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<P>Last updated: Wed May 30 19:00:33 EDT 2001</P>
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<P>Current maintainer: Bruce Momjian (<A href=
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<P>Current maintainer: Bruce Momjian (<A href=
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"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
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"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
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periodically.</P>
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periodically.</P>
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<P>Indexes are usually not used for <SMALL>ORDER BY</SMALL>
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<P>Indexes are usually not used for <SMALL>ORDER BY</SMALL>
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or joins: a sequential scan followed by an explicit sort is
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or joins. A sequential scan followed by an explicit sort is
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faster than an indexscan of all tuples of a large table, because it
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faster than an indexscan of all tuples of a large table. This
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takes fewer disk accesses.</P>
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is because random disk access is very slow.</P>
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<P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
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<P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
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<I>~,</I> indices can only be used if the beginning of the search
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<I>~,</I> indices can only be used if the beginning of the search
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