Add a couple of notes pointing out that GIN index build time is very

sensitive to maintenance_work_mem (something I just learned the hard
way).

2 files changed, 22 insertions, 4 deletions

diff --git a/doc/src/sgml/gin.sgml b/doc/src/sgml/gin.sgml
index 61a3f0f4ec1..1b7f105ac56 100644
--- a/doc/src/sgml/gin.sgml
+++ b/doc/src/sgml/gin.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.12 2007/11/13 23:36:26 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.13 2007/11/16 03:23:07 tgl Exp $ -->
 
 <chapter id="GIN">
 <title>GIN Indexes</title>
@@ -162,6 +162,17 @@
   </varlistentry>
 
   <varlistentry>
+   <term><xref linkend="guc-maintenance-work-mem"></term>
+   <listitem>
+    <para>
+     Build time for a <acronym>GIN</acronym> index is very sensitive to
+     the <varname>maintenance_work_mem</> setting; it doesn't pay to
+     skimp on work memory during index creation.
+    </para>
+   </listitem>
+  </varlistentry>
+
+  <varlistentry>
    <term><xref linkend="guc-gin-fuzzy-search-limit"></term>
    <listitem>
     <para>
@@ -177,8 +188,8 @@
     </para>
     <para>
      To facilitate controlled execution of such queries
-     <acronym>GIN</acronym> has a configurable soft upper limit on the size
-     of the returned set, the
+     <acronym>GIN</acronym> has a configurable soft upper limit on the
+     number of rows returned, the
      <varname>gin_fuzzy_search_limit</varname> configuration parameter.
      It is set to 0 (meaning no limit) by default.
      If a non-zero limit is set, then the returned set is a subset of
diff --git a/doc/src/sgml/textsearch.sgml b/doc/src/sgml/textsearch.sgml
index 0a153c465cd..b43872cca5c 100644
--- a/doc/src/sgml/textsearch.sgml
+++ b/doc/src/sgml/textsearch.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.35 2007/11/14 23:48:55 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.36 2007/11/16 03:23:07 tgl Exp $ -->
 
 <chapter id="textsearch">
  <title id="textsearch-title">Full Text Search</title>
@@ -3257,6 +3257,13 @@ EXPLAIN SELECT * FROM apod WHERE textsearch @@ to_tsquery('supernovae');
   </para>
 
   <para>
+   Note that <acronym>GIN</acronym> index build time can often be improved
+   by increasing <xref linkend="guc-maintenance-work-mem">, while
+   <acronym>GiST</acronym> index build time is not sensitive to that
+   parameter.
+  </para>
+
+  <para>
    Partitioning of big collections and the proper use of GiST and GIN indexes
    allows the implementation of very fast searches with online update.
    Partitioning can be done at the database level using table inheritance