Wiki / Configuration Parameters

Specifies the dynamic shared memory implementation that the server should use. Possible values are posix (for POSIX shared memory allocated using shm_open), sysv (for System V shared memory allocated via shmget), windows (for Windows shared memory), and mmap (to simulate shared memory using memory-mapped files stored in the data directory). Not all values are supported on all platforms; the first supported option is usually the default for that platform. The use of the mmap option, which is not the default on any platform, is generally discouraged because the operating system may write modified pages back to disk repeatedly, increasing system I/O load; however, it may be useful for debugging, when the pg_dynshmem directory is stored on a RAM disk, or when other shared memory facilities are not available. This parameter can only be set at server start.

English manual coverage begins with PostgreSQL 7.4. Source history and runtime observations have their own recorded version boundaries.

boot val

posix

category

Resource Usage / Memory

context

postmaster

documented

true

enumvals

posix, sysv, mmap

extra desc

Unknown

lang

en

max val

Unknown

metadata version

18

min val

Unknown

name

dynamic_shared_memory_type

short desc

Selects the dynamic shared memory implementation used.

source

pg-settings-source-snapshot

unit

Unknown

vartype

enum