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| author | Bruce Momjian <bruce@momjian.us> | 2006-02-24 15:00:48 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2006-02-24 15:00:48 +0000 |
| commit | 032858216caa0e820ddfe32ec4cd91a2de31a6b4 (patch) | |
| tree | 24279e57214641e6c0e1d2f95016ffb290bca3f6 | |
| parent | 39825338b4de141a300850f3211141dbb7729118 (diff) | |
| download | postgresql-032858216caa0e820ddfe32ec4cd91a2de31a6b4.tar.gz postgresql-032858216caa0e820ddfe32ec4cd91a2de31a6b4.zip | |
Backpatch FAQ changes to 8.1.X.
| -rw-r--r-- | doc/FAQ | 12 | ||||
| -rw-r--r-- | doc/FAQ_AIX | 2 | ||||
| -rw-r--r-- | doc/src/FAQ/FAQ.html | 14 |
3 files changed, 7 insertions, 21 deletions
@@ -1,7 +1,7 @@ Frequently Asked Questions (FAQ) for PostgreSQL - Last updated: Sun Feb 12 12:15:49 EST 2006 + Last updated: Fri Feb 24 09:59:35 EST 2006 Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -569,14 +569,8 @@ sequential scan followed by an explicit sort is usually faster than an index scan of a large table. However, LIMIT combined with ORDER BY often will use an index because - only a small portion of the table is returned. In fact, though MAX() - and MIN() don't use indexes, it is possible to retrieve such values - using an index with ORDER BY and LIMIT: - SELECT col - FROM tab - ORDER BY col [ DESC ] - LIMIT 1; - + only a small portion of the table is returned. + If you believe the optimizer is incorrect in choosing a sequential scan, use SET enable_seqscan TO 'off' and run query again to see if an index scan is indeed faster. diff --git a/doc/FAQ_AIX b/doc/FAQ_AIX index ff6bcdb32ee..131b38231ff 100644 --- a/doc/FAQ_AIX +++ b/doc/FAQ_AIX @@ -1,5 +1,5 @@ From: Zeugswetter Andreas <ZeugswetterA@spardat.at> -$Date: 2006/02/12 17:17:38 $ +$Date: 2006/02/24 15:00:48 $ On AIX 4.3.2 PostgreSQL compiled with the native IBM compiler xlc (vac.C 5.0.1) passes all regression tests. Other versions of OS and diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 3c10b91607a..7359ba271dc 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -10,7 +10,7 @@ alink="#0000ff"> <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> - <P>Last updated: Sun Feb 12 12:15:49 EST 2006</P> + <P>Last updated: Fri Feb 24 09:59:35 EST 2006</P> <P>Current maintainer: Bruce Momjian (<A href= "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>) @@ -742,16 +742,8 @@ table?</TD><TD>unlimited</TD></TR> usually faster than an index scan of a large table.</P> However, <SMALL>LIMIT</SMALL> combined with <SMALL>ORDER BY</SMALL> often will use an index because only a small portion of the table - is returned. In fact, though MAX() and MIN() don't use indexes, - it is possible to retrieve such values using an index with ORDER BY - and LIMIT: -<PRE> - SELECT col - FROM tab - ORDER BY col [ DESC ] - LIMIT 1; -</PRE> - + is returned.</P> + <P>If you believe the optimizer is incorrect in choosing a sequential scan, use <CODE>SET enable_seqscan TO 'off'</CODE> and run query again to see if an index scan is indeed faster.</P> |