How does memory overcommit affect PostgreSQL?

In Linux 2.4 and later, the default virtual memory behavior is not optimal for PostgreSQL. Because of the way that the kernel implements memory overcommit, the kernel may terminate the PostgreSQL server (the postmaster process) if the memory demands of another process cause the system to run out of virtual memory.

If this happens, you will see a kernel message
Out of Memory: Killed process 12345 (postmaster).

This indicates that the postmaster process has been terminated due to memory pressure. Although existing database connections will continue to function normally, no new connections will be accepted. To recover, PostgreSQL will need to be restarted.

One way to avoid this problem is to run PostgreSQL on a machine where you can be sure that other processes will not run the machine out of memory.

On Linux 2.6 and later, a better solution is to modify the kernel’s behavior so that it will not “overcommit” memory. This is done by selecting strict overcommit mode via sysctl:

sysctl -w vm.overcommit_memory=2

or placing an equivalent entry in /etc/sysctl.conf. You may also wish to modify the related setting vm.overcommit_ratio. For details see the kernel documentation file Documentation/vm/overcommit-accounting.

  • Email, SSL
  • 0 brukere syntes dette svaret var til hjelp
Var dette svaret til hjelp?

Related Articles

Installation of Geotrust True Site Icon

Installation of True Site icon: Per the subscriber agreement, you are required to install the...

Create a backup file of a SQL Server database?

Open Enterprise Manager and expand the registered SQL Server Expand Databases Right-click on...

Finding what packages are installed on a Linux system

For distributions that use RPM format packages, use the command: $ rpm -qa You may want to...

Copy MySQL database to another server through shell?

Copying MySQL Databases to another server If you are using MySQL 3.23 or later, you can copy the...

Manage Database Roles

Solution Database roles are conceptually completely separate from operating system users....