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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
368 lines
14 KiB
Plaintext
368 lines
14 KiB
Plaintext
From: Zeugswetter Andreas <ZeugswetterA@spardat.at>
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$Date: 2006/04/13 11:41:02 $
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On AIX 4.3.2 PostgreSQL compiled with the native IBM compiler xlc
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(vac.C 5.0.1) passes all regression tests. Other versions of OS and
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compiler should also work. If you don't have a powerpc or use gcc you
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might see rounding differences in the geometry regression test.
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Use the following configure flags in addition to your own
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if you have readline or libz there:
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--with-includes=/usr/local/include --with-libraries=/usr/local/lib
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There will probably be warnings about 0.0/0.0 division and duplicate
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symbols which you can safely ignore.
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Compiling PostgreSQL with gcc (2.95.3) on AIX also works.
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You need libm.a that is in the fileset bos.adt.libm. (Try the
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following command.)
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$ lslpp -l bos.adt.libm
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---
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From: Christopher Browne <cbbrowne@ca.afilias.info>
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Date: 2005-07-15
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On AIX 5.3, there have been some problems getting PostgreSQL to
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compile and run using GCC.
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1. You will want to use a version of GCC subsequent to 3.3.2,
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particularly if you use a prepackaged version. We had good
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success with 4.0.1.
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Problems with earlier versions seem to have more to do with the
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way IBM packaged GCC than with actual issues with GCC, so that if
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you compile GCC yourself, you might well have success with an
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earlier version of GCC.
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2. AIX 5.3 has a problem where sockadr_storage is not defined to be
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large enough. In version 5.3, IBM increased the size of
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sockaddr_un, the address structure for UNIX Domain Sockets, but
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did not correspondingly increase the size of sockadr_storage.
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The result of this is that attempts to use UDS with PostgreSQL
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lead to libpq overflowing the data structure. TCP/IP connections
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work OK, but not UDS, which prevents the regression tests from
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working.
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The nonconformance may be readily demonstrated by compiling and
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running the following C program which calculates and compares the
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sizes of the various structures:
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test_size.c
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------------
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---------- snip here - test_size.c ----------------------------
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#include <stdio.h>
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#include <sys/un.h>
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#include <sys/socket.h>
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int main (int argc, char *argv[]) {
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struct sockaddr_storage a;
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struct sockaddr_un b;
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printf("Size of sockadr_storage: %d\n", sizeof(a));
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printf ("Size of sockaddr_un:%d\n", sizeof(b));
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if (sizeof(a) >= sizeof(b))
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printf ("Conformant to RFC 3493\n");
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else
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printf ("Non-conformant to RFC 3493\n");
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}
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---------- snip here - test_size.c ----------------------------
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The problem was reported to IBM, and is recorded as bug report
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PMR29657.
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An immediate resolution is to alter _SS_MAXSIZE to = 1025 in
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/usr/include/sys/socket.h, which will resolve the immediate problem.
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It appears that the "final" resolution will be to alter _SS_MAXSIZE to
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1280, making the size nicely align with page boundaries.
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IBM will be providing a fix in the next maintenance release (expected
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in October 2005) with an updated socket.h.
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---
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PMR29657 was resolved in APAR IY74147: INCOMPATIBILITY BETWEEN
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SOCKADDR_UN AND SOCKADDR_STORAGE STRUCT
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APAR information
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APAR number IY74147
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Reported component name AIX 5.3
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Reported component ID 5765G0300
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Reported release 530
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Status CLOSED PER
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PE NoPE
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HIPER NoHIPER
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Submitted date 2005-07-18
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Closed date 2005-07-18
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Last modified date 2005-09-06
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If you upgrade to maintenance level 5300-03, that will include this
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fix. Use the command "oslevel -r" to determine what maintenance level
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you are at.
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---
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From: Christopher Browne <cbbrowne@ca.afilias.info>
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Date: 2005-07-15
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Some of the AIX tools may be "a little different" from what you may be
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accustomed to on other platforms. If you are looking for a version of
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ldd, useful for determining what object code depends on what
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libraries, the following URLs may help you...
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http://www.faqs.org/faqs/aix-faq/part4/section-22.html
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http://www.han.de/~jum/aix/ldd.c
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---
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From: Christopher Browne <cbbrowne@ca.afilias.info>
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Date: 2005-11-02
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On AIX 5.3 ML3 (e.g. maintenance level 5300-03), there is some problem
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with the handling of the pointer to memcpy. It is speculated that
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this relates to some linker bug that may have been introduced between
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5300-02 and 5300-03, but we have so far been unable to track down the
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cause.
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At any rate, the following patch, which "unwraps" the function
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reference, has been observed to allow PG 8.1 pre-releases to pass
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regression tests.
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The same behaviour (albeit with varying underlying functions to
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"blame") has been observed when compiling with either GCC 4.0 or IBM
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XLC.
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------------ per Seneca Cunningham -------------------
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The following patch works on the AIX 5.3 ML3 box here and didn't cause
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any problems with postgres on the x86 desktop. It's just a cleaner
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version of what I tried earlier.
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*** dynahash.c.orig Tue Nov 1 19:41:42 2005
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--- dynahash.c Tue Nov 1 20:30:33 2005
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***************
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*** 670,676 ****
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/* copy key into record */
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currBucket->hashvalue = hashvalue;
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! hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, keysize);
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/* caller is expected to fill the data field on return */
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--- 670,687 ----
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/* copy key into record */
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currBucket->hashvalue = hashvalue;
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! if (hashp->keycopy == memcpy)
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! {
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! memcpy(ELEMENTKEY(currBucket), keyPtr, keysize);
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! }
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! else if (hashp->keycopy == strncpy)
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! {
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! strncpy(ELEMENTKEY(currBucket), keyPtr, keysize);
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! }
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! else
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! {
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! hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, keysize);
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! }
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/* caller is expected to fill the data field on return */
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------------ per Seneca Cunningham -------------------
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---
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AIX, readline, and postgres 8.1.x:
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----------------------------------
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If make check doesn't work on AIX with initdb going into an infinite
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loop or failing with child processes terminated with signal 11, the
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problem could be the installed copy of readline. Previously a patch to
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dynahash.c was suggested to get around this, don't use it, better ways
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to get postgres working exist.
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See <http://archives.postgresql.org/pgsql-patches/2005-11/msg00139.php>
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for details about the problem.
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Working around the problem:
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---------------------------
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Try one of the following:
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o Use the new 8.2devel backend Makefile:
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After the matter of readline's export list and the problems that were
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occurring on AIX because of it being linked to the backend, a filter
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to exclude unneeded libraries from being linked against the backend was
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added. Get revision 1.112 of src/backend/Makefile from CVS and replace
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the copy that came with postgres with it. Build normally.
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o Use libedit
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There are a few libedit ports available online. Build and install the
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desired port. If libreadline.a can be found in /lib, /usr/lib, or in
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any location passed to postgres' configure via "--with-libraries=",
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readline will be detected and used by postgres. IBM's rpm of readline
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creates a symlink to /opt/freeware/lib/libreadline.a in /lib, so merely
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excluding /opt/freeware/lib from the passed library path does not stop
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readline from being used.
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If the linker cannot avoid finding libreadline.a, use revision 1.433
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configure.in and 1.19 config/programs.m4 from CVS, change 8.2devel to
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the appropriate 8.1.x in configure.in and run autoconf. Add the
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configure flag "--with-libedit-preferred".
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If the version of libedit used calls its "history.h" something other
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than history.h, place a symlink called history.h to it somewhere that
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the C preprocessor will check.
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o Configure with "--without-readline"
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postgres can be configured with the option "--without-readline". When
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this is enabled, postgres will not link against libreadline or libedit.
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psql will not have history, tab completion, or any of the other niceties
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that readline and libedit bring, but external readline wrappers exist
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that add that functionality.
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o Use readline 5.0
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Readline 5.0 does not induce the problems, however it does export
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memcpy and strncpy when built using the easy method of "-bexpall". Like
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4.3, it is possible to do a build that does not export these symbols,
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but it does take considerable manual effort and the creation of export
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files.
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References
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----------
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"AIX 5L Porting Guide"
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IBM Redbook
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http://www.redbooks.ibm.com/redbooks/pdfs/sg246034.pdf
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http://www.redbooks.ibm.com/abstracts/sg246034.html?Open
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"Developing and Porting C and C++ Applications on AIX"
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IBM Redbook
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http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf
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http://www.redbooks.ibm.com/abstracts/sg245674.html?Open
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-----
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AIX Memory Management: An Overview
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==================================
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by Seneca Cunningham...
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AIX can be somewhat peculiar with regards to the way it does memory
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management. You can have a server with many multiples of gigabytes of
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RAM free, but still get out of memory or address space errors when
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running applications.
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Two examples of AIX-specific memory problems
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--------------------------------------------
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Both examples were from systems with gigabytes of free RAM.
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a) createlang failing with unusual errors
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Running as the owner of the postgres install:
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-bash-3.00$ createlang plpgsql template1
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createlang: language installation failed: ERROR: could not load library
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"/opt/dbs/pgsql748/lib/plpgsql.so": A memory address is not in the
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address space for the process.
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Running as a non-owner in the group posessing the postgres install:
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-bash-3.00$ createlang plpgsql template1
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createlang: language installation failed: ERROR: could not load library
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"/opt/dbs/pgsql748/lib/plpgsql.so": Bad address
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b) out of memory errors in the postgres logs
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Every memory allocation near or greater than 256MB failing.
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The cause of these problems
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----------------------------
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The overall cause of all these problems is the default bittedness and
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memory model used by the postmaster process.
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By default, all binaries built on AIX are 32-bit. This does not
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depend upon hardware type or kernel in use. These 32-bit processes
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are limited to 4GB of memory laid out in 256MB segments using one of a
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few models. The default allows for less than 256MB in the heap as it
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shares a single segment with the stack.
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In the case of example a), above, check your umask and the permissions
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of the binaries in your postgres install. The binaries involved in
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that example were 32-bit and installed as mode 750 instead of 755.
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Due to the permissions being set in this fashion, only the owner or a
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member of the possessing group can load the library. Since it isn't
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world-readable, the loader places the object into the process' heap
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instead of the shared library segments where it would otherwise be
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placed.
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Solutions and workarounds
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-------------------------
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In this section, all build flag syntax is presented for gcc.
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The "ideal" solution for this is to use a 64-bit build of postgres,
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but that's not always practical. Systems with 32-bit processors can
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build, but not run, 64-bit binaries.
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If a 32-bit binary is desired, set LDR_CNTRL to "MAXDATA=0xn0000000",
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where 1 <= n <= 8, before starting the postmaster and try different
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values and postgresql.conf settings to find a configuration that works
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satisfactorily. This use of LDR_CNTRL tells AIX that you want the
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postmaster to have $MAXDATA bytes set aside for the heap, allocated in
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256MB segments.
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When you find a workable configuration, ldedit can be used to modify
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the binaries so that they default to using the desired heap size.
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PostgreSQL might also be rebuilt, passing configure
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LDFLAGS="-Wl,-bmaxdata:0xn0000000" to achieve the same effect.
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For a 64-bit build, set OBJECT_MODE to 64 and pass CC="gcc -maix64"
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and LDFLAGS="-Wl,-bbigtoc" to configure. If you omit the export of
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OBJECT_MODE, your build may fail with linker errors. When OBJECT_MODE
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is set, it tells AIX's build utilities such as ar, as, and ld what
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type of objects to default to handling.
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Overcommit
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----------
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By default, overcommit of paging space can happen. While I have not
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seen this occur, AIX will kill processes when it runs out of memory
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and the overcommit is accessed. The closest to this that I have seen
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is fork failing because the system decided that there was not enough
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memory for another process. Like many other parts of AIX, the paging
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space allocation method and out-of-memory kill is configurable on a
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system- or process-wide basis if this becomes a problem.
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References and resources
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------------------------
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"Large Program Support"
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AIX Documentation: General Programming Concepts: Writing and Debugging Programs
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http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixprggd/genprogc/lrg_prg_support.htm
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"Program Address Space Overview"
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AIX Documentation: General Programming Concepts: Writing and Debugging Programs
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http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixprggd/genprogc/address_space.htm
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"Performance Overview of the Virtual Memory Manager (VMM)"
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AIX Documentation: Performance Management Guide
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http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/resmgmt2.htm
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"Page Space Allocation"
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AIX Documentation: Performance Management Guide
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http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/memperf7.htm
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"Paging-space thresholds tuning"
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AIX Documentation: Performance Management Guide
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http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.doc/aixbman/prftungd/memperf6.htm
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"Developing and Porting C and C++ Applications on AIX"
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IBM Redbook
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http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf
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http://www.redbooks.ibm.com/abstracts/sg245674.html?Open
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