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Update documentation table describing how shared memory is used by 

various facilities.
This commit is contained in:
Bruce Momjian 2008-12-18 17:03:09 +00:00
parent a666d28543
commit cee63eab8d
1 changed files with 19 additions and 25 deletions
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44
doc/src/sgml/runtime.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.423 2008/12/16 19:30:43 alvherre Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.424 2008/12/18 17:03:09 momjian Exp $ -->
<chapter Id="runtime">
<title>Operating System Environment</title>
@ -1080,41 +1080,45 @@ set semsys:seminfo_semmsl=32
<table id="shared-memory-parameters">
<title>Configuration parameters affecting
<productname>PostgreSQL</productname>'s shared memory usage</>
<title><productname>PostgreSQL</productname> shared memory usage</>
<tgroup cols="2">
<thead>
<row>
<entry>Name</>
<entry>Approximate multiplier (bytes per increment) as of 8.3</>
<entry>Usage</>
<entry>Approximate shared memory bytes required (as of 8.3)</>
</row>
</thead>
<tbody>
<row>
<entry><xref linkend="guc-max-connections"></>
<entry>1800 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
<entry>Connections</>
<entry>(1800 + 270 * <xref
linkend="guc-max-locks-per-transaction">) * <xref
linkend="guc-max-connections"></entry>
</row>
<row>
<entry><xref linkend="guc-autovacuum-max-workers"></>
<entry>1800 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
<entry>Autovacuum workers</>
<entry>(1800 + 270 * <xref
linkend="guc-max-locks-per-transaction">) * <xref
linkend="guc-autovacuum-max-workers"></entry>
</row>
<row>
<entry><xref linkend="guc-max-prepared-transactions"></>
<entry>770 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
<entry>Prepared transactions</>
<entry>(770 + 270 * <xref
linkend="guc-max-locks-per-transaction">) * <xref linkend="guc-max-prepared-transactions"></entry>
</row>
<row>
<entry><xref linkend="guc-shared-buffers"></>
<entry>8400 (assuming 8 kB <symbol>BLCKSZ</>)</entry>
<entry>Shared disk buffers</>
<entry>(<xref linkend="guc-block-size"> + 208) * <xref linkend="guc-shared-buffers"></entry>
</row>
<row>
<entry><xref linkend="guc-wal-buffers"></>
<entry>8200 (assuming 8 kB <symbol>XLOG_BLCKSZ</>)</entry>
<entry>WAL buffers</>
<entry>(<xref linkend="guc-wal-block-size"> + 8) * <xref linkend="guc-wal-buffers"></entry>
</row>
<row>
@ -1125,18 +1129,8 @@ set semsys:seminfo_semmsl=32
</tgroup>
</table>
<note>
<para>
The multipliers for <varname>shared_buffers</> and
<varname>wal_buffers</> should be the number of buffers, not the
amount in bytes. To find out the number of shared or wal buffers, divide
the amount in bytes by <xref linkend="guc-block-size"> and
<xref linkend="guc-wal-block-size">, respectively.
</para>
</note>
</sect2>
<sect2>
<title>Resource Limits</title>