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Reimplement free-space-map management as per recent discussions.

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Adjustable threshold is gone in favor of keeping track of total requested
page storage and doling out proportional fractions to each relation
(with a minimum amount per relation, and some quantization of the results
to avoid thrashing with small changes in page counts).  Provide special-
case code for indexes so as not to waste space storing useless page
free space counts.  Restructure internal data storage to be a flat array
instead of list-of-chunks; this may cost a little more work in data
copying when reorganizing, but allows binary search to be used during
lookup_fsm_page_entry().
This commit is contained in:
Tom Lane
2003-03-04 21:51:22 +00:00
parent a455c94257
commit 391eb5e5b6
10 changed files with 1165 additions and 741 deletions
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14
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.169 2003/02/19 04:06:28 momjian Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.170 2003/03/04 21:51:19 tgl Exp $
-->
<Chapter Id="runtime">
@ -1725,7 +1725,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
<listitem>
<para>
Sets the maximum number of disk pages for which free space will
be tracked in the shared free-space map. The default is 10000.
be tracked in the shared free-space map. Six bytes of shared memory
are consumed for each page slot. This setting must be more than
16 * <varname>max_fsm_relations</varname>. The default is 20000.
This option can only be set at server start.
</para>
</listitem>
@ -1735,9 +1737,11 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
<term><varname>MAX_FSM_RELATIONS</varname> (<type>integer</type>)</term>
<listitem>
<para>
Sets the maximum number of relations (tables) for which free
space will be tracked in the shared free-space map. The default
is 1000. This option can only be set at server start.
Sets the maximum number of relations (tables and indexes) for which
free space will be tracked in the shared free-space map. Roughly
fifty bytes of shared memory are consumed for each slot.
The default is 1000.
This option can only be set at server start.
</para>
</listitem>
</varlistentry>