A server parameter determining the shared memory implementation to use

shared_memory_type is a configuration parameter determining which shared memory implementation to use.

shared_memory_type was added in PostgreSQL 12.


Possible values are:

  • mmap
  • sysv
  • windows

Not all values are supported on all platforms.

Default value

The default value for shared_memory_type is the first of the above values supported on the local system.

For Linux et al this will be mmap; for Windows, windows.

Use of sysv (which is not the default on any platform) is not recommended.

Change history


GUC configuration item, Memory

See also

dynamic_shared_memory_type, shared_memory_size, shared_memory_size_in_huge_pages, huge_pages