In Linux 2.4 and later, the default virtual memory behavior is not

optimal for <productname>PostgreSQL</productname>. Because of the

way that the kernel implements memory overcommit, the kernel might

terminate the <productname>PostgreSQL</productname> server (the

master server process) if the memory demands of

another process cause the system to run out of virtual memory.

terminate the <productname>PostgreSQL</productname> postmaster (the

master server process) if the memory demands of either

<productname>PostgreSQL</productname> or another process cause the

system to run out of virtual memory.

</para>

<para>

swap space are exhausted.

</para>

<para>

If <productname>PostgreSQL</productname> itself is the cause of the

system running out of memory, you can avoid the problem by changing

your configuration. In some cases, it may help to lower memory-related

configuration parameters, particularly

<link linkend="guc-shared-buffers"><varname>shared_buffers</></link>

and <link linkend="guc-work-mem"><varname>work_mem</></link>. In

other cases, the problem may be caused by allowing too many connections

to the database server itself. In many cases, it may be better to reduce

<link linkend="guc-max-connections"><varname>max_connections</></link>

and instead make use of external connection-pooling software.

</para>

<para>

On Linux 2.6 and later, it is possible to modify the

kernel's behavior so that it will not <quote>overcommit</> memory.