From 391eb5e5b6a78fce5179808379cdae20baedd9c3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 4 Mar 2003 21:51:22 +0000
Subject: Reimplement free-space-map management as per recent discussions.
 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().

---
 doc/src/sgml/runtime.sgml | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index b023940dc3d..86d5ddc2852 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -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>
-- 
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