51.87. pg_shmem_allocations

51.87. `pg_shmem_allocations`
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51.87. `pg_shmem_allocations`

The pg_shmem_allocations view shows allocations made from the server's main shared memory segment. This includes both memory allocated by postgres itself and memory allocated by extensions using the mechanisms detailed in Section 37.10.10.

Note that this view does not include memory allocated using the dynamic shared memory infrastructure.

Table 51.88. pg_shmem_allocations Columns

Column Type Description
`name` `text` The name of the shared memory allocation. NULL for unused memory and `<anonymous>` for anonymous allocations.
`off` `int8` The offset at which the allocation starts. NULL for anonymous allocations, since details related to them are not known.
`size` `int8` Size of the allocation
`allocated_size` `int8` Size of the allocation including padding. For anonymous allocations, no information about padding is available, so the `size` and `allocated_size` columns will always be equal. Padding is not meaningful for free memory, so the columns will be equal in that case also.

Column Type

Description

name text

The name of the shared memory allocation. NULL for unused memory and <anonymous> for anonymous allocations.

off int8

The offset at which the allocation starts. NULL for anonymous allocations, since details related to them are not known.

size int8

Size of the allocation

allocated_size int8

Size of the allocation including padding. For anonymous allocations, no information about padding is available, so the size and allocated_size columns will always be equal. Padding is not meaningful for free memory, so the columns will be equal in that case also.

Anonymous allocations are allocations that have been made with ShmemAlloc() directly, rather than via ShmemInitStruct() or ShmemInitHash().

By default, the pg_shmem_allocations view can be read only by superusers.