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Update FAQ.
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doc/FAQ

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Frequently Asked Questions (FAQ) for PostgreSQL
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Last updated: Mon Jan 27 01:24:42 EST 2003
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Last updated: Thu Feb 13 23:07:35 EST 2003
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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doc/src/FAQ/FAQ.html

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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
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<P>Last updated: Thu Dec 5 00:47:26 EST 2002</P>
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<P>Last updated: Thu Feb 13 23:07:35 EST 2003</P>
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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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<H4><A name="1.7">1.7</A>) What is the latest release?</H4>
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<P>The latest release of PostgreSQL is version 7.2.3.</P>
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<P>The latest release of PostgreSQL is version 7.3.1.</P>
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<P>We plan to have major releases every four months.</P>
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interface?</H4>
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Yes, there are several graphical interfaces to PostgreSQL available.
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These include PgAccess <a href="http://www.pgaccess.com">
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http://www.pgaccess.com</a>), PgAdmin II (<a
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These include PgAccess <a href="http://www.pgaccess.org">
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http://www.pgaccess.org</a>), PgAdmin II (<a
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href="http://www.pgadmin.org">http://www.pgadmin.org</a>,
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Win32-only), RHDB Admin (<a
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href="http://sources.redhat.com/rhdb/">http://sources.redhat.com/rhdb/
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http://phppgadmin.sourceforge.net/ </a>), a web-based interface to
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PostgreSQL.
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<P>We have a nice graphical user interface called PgAccess which can
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also be used as a report generator. The Web page is
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<A href="http://www.pgaccess.org/">http://www.pgaccess.org/</A>.</P>
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<H4><A name="2.4">2.4</A>) What languages are able to communicate with
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PostgreSQL?</H4>
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the number of allowed backend processes is so your system won't run
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out of resources.</P>
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<P>In PostgreSQL versions prior to 6.5, the maximum number of
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backends was 64, and changing it required a rebuild after altering
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the MaxBackendId constant in
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<I>include/storage/sinvaladt.h</I>.</P>
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<H4><A name="3.9">3.9</A>) What is in the <I>pgsql_tmp</I> directory?</H4>
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<P>This directory contains temporary files generated by the query
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LIMIT 1;
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</PRE>
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<P>If you believe the optimizer is incorrect in choosing a
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sequential scan, use <CODE>SET enable_seqscan TO 'off'</CODE> and
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run tests to see if an index scan is indeed faster.</P>
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<P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
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<I>~</I>, indexes can only be used in certain circumstances:</P>
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<UL>
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<PRE>
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Type Internal Name Notes
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--------------------------------------------------
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"char" char 1 character
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CHAR(n) bpchar blank padded to the specified fixed length
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VARCHAR(n) varchar size specifies maximum length, no padding
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CHAR(n) bpchar blank padded to the specified fixed length
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TEXT text no specific upper limit on length
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"char" char one character
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BYTEA bytea variable-length byte array (null-byte safe)
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</PRE>
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stored out-of-line by <SMALL>TOAST</SMALL>, so the space on disk
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might also be less than expected.</P>
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<P><SMALL>CHAR(n)</SMALL> is best when storing strings that are
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usually the same length. <SMALL>VARCHAR(n)</SMALL> is best when
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storing variable-length strings but it limits how long a string can
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be. <SMALL>TEXT</SMALL> is for strings of unlimited length, maximum
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1 gigabyte. <SMALL>BYTEA</SMALL> is for storing binary data,
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<SMALL>VARCHAR(n)</SMALL> is best when storing variable-length
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strings and it limits how long a string can be. <SMALL>TEXT</SMALL>
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is for strings of unlimited length, with a maximum of one gigabyte.
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<P><SMALL>CHAR(n)</SMALL> is for storing strings that are all the
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same length. <SMALL>CHAR(n)</SMALL> pads with blanks to the specified
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length, while <SMALL>VARCHAR(n)</SMALL> only stores the characters
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supplied. <SMALL>BYTEA</SMALL> is for storing binary data,
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particularly values that include <SMALL>NULL</SMALL> bytes. These
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types have similar performance characteristics.</P>
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</PRE>
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For this to be fast, <CODE>subcol</CODE> should be an indexed column.
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We hope to fix this limitation in a future release.
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This preformance problem will be fixed in 7.4.
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<H4><A name="4.23">4.23</A>) How do I perform an outer join?</H4>
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