Update AIX FAQ:

At any rate, here's a revision to CVS HEAD to reflect some changes by
myself and by Seneca Cunningham for the AIX FAQ.  It touches on the
following issues:

1.  memcpy pointer patch for dynahash.c

2.  AIX memory management, which can, for 32 bit cases, bite people
    quite unexpectedly...

Chris Browne

doc/FAQ

@@ -1,7 +1,7 @@
 
                 Frequently Asked Questions (FAQ) for PostgreSQL
                                        
-   Last updated: Sun Apr 2 23:40:12 EDT 2006
+   Last updated: Wed Apr 12 16:03:39 EDT 2006
    
    Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
    
@@ -25,7 +25,7 @@
    1.9) How do I find out about known bugs or missing features?
    1.10) What documentation is available?
    1.11) How can I learn SQL?
-   1.12) How do I join the development team?
+   1.12) How do I submit a patch or join the development team?
    1.13) How does PostgreSQL compare to other DBMSs?
    
                            User Client Questions
@@ -275,7 +275,7 @@
    http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM,
    and at http://sqlcourse.com.
    
-  1.12) How do I join the development team?
+  1.12) How do I submit a patch or join the development team?
   
    See the Developer's FAQ.
    
@@ -507,7 +507,8 @@
    files so file system size limits are not important.
    
    The maximum table size, row size, and maximum number of columns can be
-   quadrupled by increasing the default block size to 32k.
+   quadrupled by increasing the default block size to 32k. The maximum
+   table size can also be increased using table partitioning.
    
    One limitation is that indexes can not be created on columns longer
    than about 2,000 characters. Fortunately, such indexes are rarely

doc/FAQ_AIX

@@ -1,5 +1,5 @@
 From: Zeugswetter Andreas <ZeugswetterA@spardat.at>
-$Date: 2006/04/11 21:23:27 $
+$Date: 2006/04/13 11:42:35 $
 
 On AIX 4.3.2 PostgreSQL compiled with the native IBM compiler xlc
 (vac.C 5.0.1) passes all regression tests.  Other versions of OS and
@@ -113,6 +113,68 @@ libraries, the following URLs may help you...
 http://www.faqs.org/faqs/aix-faq/part4/section-22.html
 
 http://www.han.de/~jum/aix/ldd.c
+
+---
+From: Christopher Browne <cbbrowne@ca.afilias.info>
+Date: 2005-11-02
+
+On AIX 5.3 ML3 (e.g. maintenance level 5300-03), there is some problem
+with the handling of the pointer to memcpy.  It is speculated that
+this relates to some linker bug that may have been introduced between
+5300-02 and 5300-03, but we have so far been unable to track down the
+cause.
+
+At any rate, the following patch, which "unwraps" the function
+reference, has been observed to allow PG 8.1 pre-releases to pass
+regression tests.
+
+The same behaviour (albeit with varying underlying functions to
+"blame") has been observed when compiling with either GCC 4.0 or IBM
+XLC.
+
+------------ per Seneca Cunningham -------------------
+
+The following patch works on the AIX 5.3 ML3 box here and didn't cause
+any problems with postgres on the x86 desktop.  It's just a cleaner
+version of what I tried earlier.
+
+*** dynahash.c.orig Tue Nov  1 19:41:42 2005
+--- dynahash.c  Tue Nov  1 20:30:33 2005
+***************
+*** 670,676 ****
+
+
+            /* copy key into record */
+            currBucket->hashvalue = hashvalue;
+!           hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, keysize);
+
+
+            /* caller is expected to fill the data field on return */
+
+
+--- 670,687 ----
+
+
+            /* copy key into record */
+            currBucket->hashvalue = hashvalue;
+!           if (hashp->keycopy == memcpy)
+!           {
+!               memcpy(ELEMENTKEY(currBucket), keyPtr, keysize);
+!           }
+!           else if (hashp->keycopy == strncpy)
+!           {
+!               strncpy(ELEMENTKEY(currBucket), keyPtr, keysize);
+!           }
+!           else
+!           {
+!               hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, keysize);
+!           }
+
+
+            /* caller is expected to fill the data field on return */
+
+------------ per Seneca Cunningham -------------------
+
 ---
 
 AIX, readline, and postgres 8.1.x:
@@ -185,3 +247,121 @@ References
   IBM Redbook
   http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf
   http://www.redbooks.ibm.com/abstracts/sg245674.html?Open
+
+-----
+
+AIX Memory Management: An Overview
+==================================
+
+by Seneca Cunningham...
+
+AIX can be somewhat peculiar with regards to the way it does memory
+management.  You can have a server with many multiples of gigabytes of
+RAM free, but still get out of memory or address space errors when
+running applications.
+
+Two examples of AIX-specific memory problems
+--------------------------------------------
+Both examples were from systems with gigabytes of free RAM.
+
+a) createlang failing with unusual errors
+    Running as the owner of the postgres install:
+        -bash-3.00$ createlang plpgsql template1
+        createlang: language installation failed: ERROR:  could not load library
+        "/opt/dbs/pgsql748/lib/plpgsql.so": A memory address is not in the 
+        address space for the process.
+    
+    Running as a non-owner in the group posessing the postgres install:
+        -bash-3.00$ createlang plpgsql template1
+        createlang: language installation failed: ERROR:  could not load library 
+        "/opt/dbs/pgsql748/lib/plpgsql.so": Bad address
+
+b) out of memory errors in the postgres logs
+    Every memory allocation near or greater than 256MB failing.
+
+
+The cause of these problems
+----------------------------
+
+The overall cause of all these problems is the default bittedness and
+memory model used by the postmaster process.
+
+By default, all binaries built on AIX are 32-bit.  This does not
+depend upon hardware type or kernel in use.  These 32-bit processes
+are limited to 4GB of memory laid out in 256MB segments using one of a
+few models.  The default allows for less than 256MB in the heap as it
+shares a single segment with the stack.
+
+In the case of example a), above, check your umask and the permissions
+of the binaries in your postgres install.  The binaries involved in
+that example were 32-bit and installed as mode 750 instead of 755.
+Due to the permissions being set in this fashion, only the owner or a
+member of the possessing group can load the library.  Since it isn't
+world-readable, the loader places the object into the process' heap
+instead of the shared library segments where it would otherwise be
+placed.
+
+Solutions and workarounds
+-------------------------
+In this section, all build flag syntax is presented for gcc.
+
+The "ideal" solution for this is to use a 64-bit build of postgres,
+but that's not always practical.  Systems with 32-bit processors can
+build, but not run, 64-bit binaries.  
+
+If a 32-bit binary is desired, set LDR_CNTRL to "MAXDATA=0xn0000000",
+where 1 <= n <= 8, before starting the postmaster and try different
+values and postgresql.conf settings to find a configuration that works
+satisfactorily.  This use of LDR_CNTRL tells AIX that you want the
+postmaster to have $MAXDATA bytes set aside for the heap, allocated in
+256MB segments.
+
+When you find a workable configuration, ldedit can be used to modify
+the binaries so that they default to using the desired heap size.
+
+PostgreSQL might also be rebuilt, passing configure
+LDFLAGS="-Wl,-bmaxdata:0xn0000000" to achieve the same effect.
+
+For a 64-bit build, set OBJECT_MODE to 64 and pass CC="gcc -maix64"
+and LDFLAGS="-Wl,-bbigtoc" to configure.  If you omit the export of
+OBJECT_MODE, your build may fail with linker errors.  When OBJECT_MODE
+is set, it tells AIX's build utilities such as ar, as, and ld what
+type of objects to default to handling.
+
+Overcommit
+----------
+
+By default, overcommit of paging space can happen.  While I have not
+seen this occur, AIX will kill processes when it runs out of memory
+and the overcommit is accessed.  The closest to this that I have seen
+is fork failing because the system decided that there was not enough
+memory for another process.  Like many other parts of AIX, the paging
+space allocation method and out-of-memory kill is configurable on a
+system- or process-wide basis if this becomes a problem.
+
+References and resources
+------------------------
+"Large Program Support"
+  AIX Documentation: General Programming Concepts: Writing and Debugging Programs
+  http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixprggd/genprogc/lrg_prg_support.htm
+
+"Program Address Space Overview"
+  AIX Documentation: General Programming Concepts: Writing and Debugging Programs
+  http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixprggd/genprogc/address_space.htm
+
+"Performance Overview of the Virtual Memory Manager (VMM)"
+  AIX Documentation: Performance Management Guide
+  http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/resmgmt2.htm
+
+"Page Space Allocation"
+  AIX Documentation: Performance Management Guide
+  http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/memperf7.htm
+
+"Paging-space thresholds tuning"
+  AIX Documentation: Performance Management Guide
+  http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/memperf6.htm
+
+"Developing and Porting C and C++ Applications on AIX"
+  IBM Redbook
+  http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf
+  http://www.redbooks.ibm.com/abstracts/sg245674.html?Open

doc/src/FAQ/FAQ.html

@@ -10,7 +10,7 @@
   alink="#0000ff">
     <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
 
-    <P>Last updated: Sun Apr  2 23:40:12 EDT 2006</P>
+    <P>Last updated: Wed Apr 12 16:03:39 EDT 2006</P>
 
     <P>Current maintainer: Bruce Momjian (<A href=
     "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)
@@ -38,7 +38,8 @@
      missing features?<BR>
      <A href="#item1.10">1.10</A>) What documentation is available?<BR>
      <A href="#item1.11">1.11</A>) How can I learn <SMALL>SQL</SMALL>?<BR>
-     <A href="#item1.12">1.12</A>) How do I join the development team?<BR>
+     <A href="#item1.12">1.12</A>) How do I submit a patch or join the
+     development team?<BR>
      <A href="#item1.13">1.13</A>) How does PostgreSQL compare to other
     <SMALL>DBMS</SMALL>s?<BR>
      
@@ -363,7 +364,7 @@
     and at <A href=
     "http://sqlcourse.com/">http://sqlcourse.com.</A></P>
 
-    <H3 id="item1.12">1.12) How do I join the development
+    <H3 id="item1.12">1.12) How do I submit a patch or join the development
     team?</H3>
 
     <P>See the <a href="http://www.postgresql.org/docs/faqs.FAQ_DEV.html">
@@ -674,7 +675,8 @@ table?</TD><TD>unlimited</TD></TR>
     important.</P>
 
     <P>The maximum table size, row size, and maximum number of columns
-    can be quadrupled by increasing the default block size to 32k.</P>
+    can be quadrupled by increasing the default block size to 32k.  The
+    maximum table size can also be increased using table partitioning.</P>
 
     <P>One limitation is that indexes can not be created on columns
     longer than about 2,000 characters. Fortunately, such indexes are