MEMORY_TRIM

Calls glibc function to reclaim free memory from malloc and return it to the operating system.

Calls glibc function malloc_trim() to reclaim free memory from malloc and return it to the operating system. Details on the trim operation are written to system table MEMORY_EVENTS.

Unless you turn off memory polling, Vertica automatically detects when glibc accumulates an excessive amount of free memory in its allocation arena. When this occurs, Vertica consolidates much of this memory and returns it to the operating system. Call this function if you disable memory polling and wish to reduce glibc-allocated memory manually.

For more information, see Memory trimming.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Volatile

Syntax

MEMORY_TRIM()

Privileges

Superuser

Examples

=> SELECT memory_trim();
                           memory_trim
-----------------------------------------------------------------
 Pre-RSS: [378822656] Post-RSS: [372129792] Benefit: [0.0176675]
(1 row)