Update of /home/cvsd/slony1/slony1-engine/doc/adminguide
In directory main.slony.info:/tmp/cvs-serv12997

Modified Files:
      Tag: REL_1_2_STABLE
	faq.sgml 
Log Message:
Add in docs on problem with UPDATE FUNCTIONS on PG 8.1.[0-3]


Index: faq.sgml
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RCS file: /home/cvsd/slony1/slony1-engine/doc/adminguide/faq.sgml,v
retrieving revision 1.66.2.5
retrieving revision 1.66.2.6
diff -C2 -d -r1.66.2.5 -r1.66.2.6
*** faq.sgml	6 Jun 2007 22:17:10 -0000	1.66.2.5
--- faq.sgml	11 Jun 2007 16:00:58 -0000	1.66.2.6
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*** 163,166 ****
--- 163,236 ----
  </qandaentry>
  
+ <qandaentry id="pg81funs">
+ 
+ <question> <para> I'm trying to upgrade to a newer version of &slony1;
+ and am running into a problem with <xref
+ linkend="stmtupdatefunctions">.  When I run <xref
+ linkend="stmtupdatefunctions">, my
+ <application>postmaster</application> falls over with a Signal 11.
+ There aren't any seeming errors in the log files, aside from the
+ &postgres; logs indicating that, yes indeed, the postmaster fell
+ over.</para>
+ 
+ <para> I connected a debugger to the core file, and it indicates that
+ it was trying to commit a transaction at the time of the
+ failure. </para>
+ 
+ <para> By the way I'm on &postgres; 8.1.[0-3]. </para>
+ </question>
+ 
+ <answer> <para> Unfortunately, early releases of &postgres; 8.1 had a
+ problem where if you redefined a function (such as, say,
+ <function>upgradeSchema(text)</function>), and then, in the same
+ transaction, ran that function, the
+ <application>postmaster</application> would fall over, and the
+ transaction would fail to commit.  </para>
+ 
+ <para> The &lslonik; command <xref linkend="stmtupdatefunctions">
+ functions like that; it, in one transaction, tries to:
+ 
+ <itemizedlist>
+ <listitem><para> Load the new functions (from <filename>slony1_funcs.sql</filename>), notably including <function>upgradeSchema(text)</function>.  </para> </listitem>
+ <listitem><para> Run <function>upgradeSchema(text)</function> to do any necessary upgrades to the database schema. </para> </listitem>
+ <listitem><para> Notify &lslon; processes of a change of configuration.</para> </listitem>
+ </itemizedlist>
+ </para>
+ 
+ <para> Unfortunately, on &postgres; 8.1.0, 8.1.1, 8.1.2, and 8.1.3,
+ this conflicts with a bug where using and modifying a plpgsql function
+ in the same transaction leads to a crash. </para>
+ 
+ <para> Several workarounds are available. </para>
+ 
+ </answer>
+ 
+ <answer> <para> The preferred answer would be to upgrade &postgres; to
+ 8.1.4 or some later version.  Changes between minor versions do not
+ require rebuilding databases; it should merely require copying a
+ suitable 8.1.x build into place, and restarting the
+ <application>postmaster</application> with the new version.  </para>
+ </answer>
+ 
+ <answer><para> If that is unsuitable, it would be possible to perform
+ the upgrade via a series of transactions, performing the equivalent of
+ what &lslonik; does <quote>by hand</quote>: </para>
+ 
+ <itemizedlist>
+ <listitem><para> Take <filename>slony1_funcs.sql</filename> and do three replacements within it: </para> 
+ 
+ <itemizedlist>
+ <listitem><para> Replace <quote>@CLUSTERNAME@</quote> with the name of the cluster </para> </listitem>
+ <listitem><para> Replace <quote>@MODULEVERSION@</quote> with the &slony1; version string, such as <quote>1.2.10</quote> </para> </listitem>
+ <listitem><para> Replace <quote>@NAMESPACE@</quote> with the <quote>double-quoted</quote> name of the cluster namespace, such as "_MyCluster" </para> </listitem>
+ </itemizedlist>
+ </listitem>
+ <listitem><para> Load that <quote>remapped</quote> set of functions into the database.</para> </listitem>
+ <listitem><para> Run the stored function via <command>select <function>upgradeSchema('1.2.7')</function>; </command>, assuming that the previous version of &slony1; in use was version 1.2.7. </para> </listitem>
+ <listitem><para> Restarting all &lslon; processes would probably be a wise move with this sort of <quote>surgery.</quote> </para> </listitem>
+ </itemizedlist>
+ </answer>
+ </qandaentry>
+ 
  </qandadiv>