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@ -10,7 +10,7 @@ |
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alink="#0000ff"> |
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> |
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<P>Last updated: Tue Feb 1 16:10:47 EST 2005</P> |
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<P>Last updated: Wed Feb 2 08:40:42 EST 2005</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>) |
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@ -61,11 +61,9 @@ |
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<A href="#3.4">3.4</A>) What debugging features are available?<BR> |
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<A href="#3.5">3.5</A>) Why do I get <I>"Sorry, too many |
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clients"</I> when trying to connect?<BR> |
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<A href="#3.6">3.6</A>) What is in the <I>pgsql_tmp</I> |
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directory?<BR> |
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<A href="#3.7">3.7</A>) Why do I need to do a dump and restore |
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<A href="#3.6">3.6</A>) Why do I need to do a dump and restore |
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to upgrade PostgreSQL releases?<BR> |
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<A href="#3.8">3.8</A>) What computer hardware should I use?<BR> |
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<A href="#3.7">3.7</A>) What computer hardware should I use?<BR> |
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<H2 align="center">Operational Questions</H2> |
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@ -573,19 +571,7 @@ |
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<I>max_connections</I> value in <I>postgresql.conf</I> and |
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restarting the <I>postmaster</I>.</P> |
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<H4><A name="3.6">3.6</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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executor. For example, if a sort needs to be done to satisfy an |
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<SMALL>ORDER BY</SMALL> and the sort requires more space than the |
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backend's <I>-S</I> parameter allows, then temporary files are created |
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here to hold the extra data.</P> |
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<P>The temporary files are usually deleted automatically, but might |
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remain if a backend crashes during a sort. A stop and restart of the |
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<I>postmaster</I> will remove files from those directories.</P> |
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<H4><A name="3.7">3.7</A>) Why do I need to do a dump and restore |
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<H4><A name="3.6">3.6</A>) Why do I need to do a dump and restore |
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to upgrade between major PostgreSQL releases?</H4> |
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<P>The PostgreSQL team makes only small changes between minor releases, |
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@ -596,7 +582,7 @@ |
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data in a generic format that can then be loaded in using the new internal |
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format.</P> |
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<H4><A name="3.8">3.8</A>) What computer hardware should I use?</H4> |
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<H4><A name="3.7">3.7</A>) What computer hardware should I use?</H4> |
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<P>Because PC hardware is mostly compatible, people tend to believe that |
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all PC hardware is of equal quality. It is not. ECC RAM, SCSI, and |
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@ -672,7 +658,7 @@ |
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table, and a database?</H4> |
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<P>These are the limits:</P> |
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<CENTER> |
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<BLOCKQUOTE> |
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<TABLE BORDER=1> |
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<TR><TD>Maximum size for a database?</TD><TD>unlimited (32 TB databases |
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exist)</TD></TR> |
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@ -685,8 +671,7 @@ on column types</TD></TR> |
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<TR><TD>Maximum number of indexes on a |
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table?</TD><TD>unlimited</TD></TR> |
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</TABLE> |
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</CENTER> |
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<BR> |
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</BLOCKQUOTE> |
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<P>Of course, these are not actually unlimited, but limited to |
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available disk space and memory/swap space. Performance may suffer |
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@ -837,7 +822,7 @@ table?</TD><TD>unlimited</TD></TR> |
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<H4><A name="4.10">4.10</A>) What is the difference between the |
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various character types?</H4> |
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<CENTER> |
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<BLOCKQUOTE> |
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<TABLE BORDER=1> |
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<TR><TH>Type</TH><TH>Internal Name</TH><TH>Notes</TH></TR> |
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<TR><TD>VARCHAR(n)</TD><TD>varchar</TD><TD>size specifies maximum |
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@ -850,7 +835,8 @@ length</TD></TR> |
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(null-byte safe)</TD></TR> |
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<TR><TD>"char"</TD><TD>char</TD><TD>one character</TD></TR> |
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</TABLE> |
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</CENTER> |
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</BLOCKQUOTE> |
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<P>You will see the internal name when examining system catalogs |
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and in some error messages.</P> |
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