Tom Lane wrote:
> Greg Smith <gsmith@xxxxxxxxxxxxx> writes:
> > On Wed, 26 Dec 2007, Guillaume Smet wrote:
> >> beta RPMs are by default compiled with --enable-debug and
> >> --enable-cassert which doesn't help them to fly fast...
>
> > Got that right. Last time I was going crazy after running pgbench with
> > those options and not having realized what I changed, I was getting a 50%
> > slowdown on results that way compared to without the debugging stuff.
> > Didn't realize it scaled with shared_buffers though.
>
> See AtEOXact_Buffers(). There are probably any number of other
> interesting scaling behaviors --- in my tests, AllocSetCheck() is
> normally a major cycle-eater if --enable-cassert is set, and that costs
> time proportional to the number of memory chunks allocated by the query.
>
> Currently the docs say that --enable-cassert
>
> Enables <firstterm>assertion</> checks in the server, which test for
> many <quote>cannot happen</> conditions. This is invaluable for
> code development purposes, but the tests slow things down a little.
>
> Maybe we ought to put that more strongly --- s/a little/significantly/,
> perhaps?
Docs updated with attached patch, backpatched to 8.3.X.
--
Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/installation.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/installation.sgml,v
retrieving revision 1.302
diff -c -c -r1.302 installation.sgml
*** doc/src/sgml/installation.sgml 17 Feb 2008 16:36:43 -0000 1.302
--- doc/src/sgml/installation.sgml 6 Mar 2008 21:36:39 -0000
***************
*** 1144,1157 ****
<para>
Enables <firstterm>assertion</> checks in the server, which test for
many <quote>cannot happen</> conditions. This is invaluable for
! code development purposes, but the tests slow things down a little.
Also, having the tests turned on won't necessarily enhance the
stability of your server! The assertion checks are not categorized
for severity, and so what might be a relatively harmless bug will
still lead to server restarts if it triggers an assertion
! failure. Currently, this option is not recommended for
! production use, but you should have it on for development work
! or when running a beta version.
</para>
</listitem>
</varlistentry>
--- 1144,1158 ----
<para>
Enables <firstterm>assertion</> checks in the server, which test for
many <quote>cannot happen</> conditions. This is invaluable for
! code development purposes, but the tests can slow down the
! server significantly.
Also, having the tests turned on won't necessarily enhance the
stability of your server! The assertion checks are not categorized
for severity, and so what might be a relatively harmless bug will
still lead to server restarts if it triggers an assertion
! failure. This option is not recommended for production use, but
! you should have it on for development work or when running a beta
! version.
</para>
</listitem>
</varlistentry>
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