PostgreSQL version:

shared_buffers

Sets the amount of memory the database server uses for shared memory buffers. The default is typically 128 megabytes (128MB), but might be less if your kernel settings will not support it (as determined during initdb). This setting must be at least 128 kilobytes. (Non-default values of BLCKSZ change the minimum.) However, settings significantly higher than the minimum are usually needed for good performance. This parameter can only be set at server start.

If you have a dedicated database server with 1GB or more of RAM, a reasonable starting value for shared_buffers is 25% of the memory in your system. There are some workloads where even larger settings for shared_buffers are effective, but because PostgreSQL also relies on the operating system cache, it is unlikely that an allocation of more than 40% of RAM to shared_buffers will work better than a smaller amount. Larger settings for shared_buffers usually require a corresponding increase in max_wal_size, in order to spread out the process of writing large quantities of new or changed data over a longer period of time.

On systems with less than 1GB of RAM, a smaller percentage of RAM is appropriate, so as to leave adequate space for the operating system.

Recommendations

A memory quantity defining PostgreSQL's "dedicated" RAM, which is used for connection control, active operations, and more. However, since PostgreSQL also needs free RAM for file system buffers, sorts and maintenance operations, it is not advisable to set shared_buffers to a majority of RAM. Note that increasing shared_buffers often requires you to increase some system kernel parameters, most notably SHMMAX and SHMALL. See Operating System Environment: Managing Kernel Resources in the PostgreSQL documentation for more details. Also note that shared_buffers over 2GB is only supported on 64-bit systems.

Comments

At postgresqlCO.NF (OnGres) we value your privacy and treat all data very seriously. We're fully GDPR compliant, and we continuously monitor and improve our data storage, retention and compliance mechanisms.

This web page does not, however, store any PII (Personally Identifiable Information). The only service that stores any data is Google Analytics, and we use it to gather analytics of the web page.

This website contains some data from the official documentation of the PostgreSQL.org project, and from Annotated.Conf, used with permission.

If you have any question or concern about our terms of service or privacy policy, please contact us at dataprotection _at_ ongres _dot_ com.

OK