out of memory

SQLSTATE 53200 condition out_of_memory class 53 — Insufficient Resources severity ERROR

Reproduced & verified on PostgreSQL 14.23, 15.18, 16.14, 17.10 and 18.4 — identical message on every version.

Last reviewed 11 Jun 2026 · Reproduced live with the SQL on this page.

Symptoms

A backend could not allocate memory while executing a query. PostgreSQL raises SQLSTATE 53200 (out_of_memory) and aborts the statement.

A memory allocation failed during query execution.
Common with very high work_mem and many concurrent operations.
A memory-context dump usually accompanies it in the log.

What the server log shows

ERROR:  out of memory
DETAIL:  Failed on request of size 8388608 in memory context "ExecutorState".

Why PostgreSQL raises this — what the manual says

Section 19.4.1 Memory (work_mem):

“Sets the base maximum amount of memory to be used by a query operation (such as a sort or hash table) before writing to temporary disk files.”

Each backend allocates from process and OS memory. A large sort/hash with a high work_mem, multiplied across operations and connections, can exhaust available memory, so the allocation fails and PostgreSQL reports 53200.

Common causes

work_mem set too high for the concurrency level.
A query with many memory-hungry operations (big hashes/sorts).
Overall server memory pressure or OS overcommit limits.

Relevant GUC parameters

Parameter	Default	Effect
`work_mem`	4MB	Per-operation memory budget; high values multiply across operations/sessions.
`hash_mem_multiplier`	2.0	Scales the memory available to hash-based operations.

How to fix it

Lower work_mem (globally or per session) and re-test.
Optimize the query to reduce memory-intensive operations.
Add RAM or reduce concurrency; review OS overcommit settings.

Related & next steps

Reference: PostgreSQL 18 Section 20.4 “Resource Consumption”.