default_table_access_method

default_table_access_method is the PostgreSQL setting that defines the default table access method for new tables.

Note

Fact — official short description: “Sets the default table access method for new tables.”

Identity

Type , Valuestring: Upstream pg_settings type
Context , Valueuser: Settable by an ordinary user
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueClient Connection Defaults / Statement Behavior: Upstream classification
Latest boot value , Valueheap: heap

Lifecycle

Fact	Value
First observed	PG12
Present in	PG12–19 Beta 3
Removed in	No
Introduction commit	`8586bf7ed888` — tableam: introduce table AM infrastructure.
Commit date	2019-03-06
Discussion	thread 1

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG12–19 Beta 3	`heap`	—	heap

How it works

default_table_access_method sets the default table access method for new tables. It is consulted only when CREATE TABLE, CREATE MATERIALIZED VIEW, or SELECT INTO does not name an access method; existing relations are unchanged.

default_table_access_method is a USER-context setting. An authorized role can change it for a session, while ALTER ROLE or ALTER DATABASE can establish a default for future sessions.

It supplies a default only when SQL omits an explicit choice, so schema migrations, object-level options, privileges, and later ALTER operations can override or outlive it.

Tuning advice

Tip

Advice. These are workload-specific starting points and must be validated with measurements.

Workload	Guidance
OLTP	Keep heap unless a production-ready alternative access method has been tested for concurrency, WAL, backup, replication, upgrades, and tooling; name the choice explicitly in critical DDL.
OLAP	Benchmark an alternative with representative scans, loads, updates, and maintenance, then scope it to dedicated objects rather than changing the default prematurely.
Small nodes	Use heap. An alternative access method adds operational dependencies and is not a generic remedy for limited hardware.

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG19 Beta 3; this does not assert current Pigsty support for that historical or beta release.

Template	Effective value	Versus upstream boot	Source expression
OLTP	Unmodified	—	—
OLAP	Unmodified	—	—
CRIT	Unmodified	—	—
TINY	Unmodified	—	—

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG12–19 Beta 3 unmodified; OLAP: PG12–19 Beta 3 unmodified; CRIT: PG12–19 Beta 3 unmodified; TINY: PG12–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Changing default_table_access_method in one session and assuming role defaults, database defaults, or other pooled sessions changed with it.
Expecting a changed default to rewrite existing objects or override explicit DDL clauses.
Ignoring tablespace privileges, installed access methods or compression support, and restore portability.
Changing default_table_access_method globally without a rollback plan and a client or operational compatibility test.

default_tablespace · temp_tablespaces · default_toast_compression · check_function_bodies · maintenance_work_mem