# sql_inheritance

> sql_inheritance — Causes subtables to be included by default in various commands. Observed in PG9.0–9.6; its last measured boot default is on in PG9.6, with user context. It was removed in PG10.
---

> [!NOTE]
> **Fact — official short description:** “Causes subtables to be included by default in various commands.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `bool` | Upstream pg_settings type |
| Context | `user` | Settable by an ordinary user |
| Unit | — | Raw unit |
| Range | — | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Version and Platform Compatibility / Previous PostgreSQL Versions | Upstream classification |
| Latest boot value | `on` | on |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG9.0 (research boundary) |
| Present in | PG9.0–9.6 |
| Removed in | PG10 |
| Introduction commit | Not asserted: predates the PG9.0 research boundary |
| Commit date | — |
| Discussion | — |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG9.0–9.6 | `on` | — | on |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

PostgreSQL describes sql_inheritance as follows: “Causes subtables to be included by default in various commands.” It can be changed per session, which makes plan or behavior comparisons possible without changing every workload. The atlas measures it in PG9.0–9.6; boot_val is the compiled or initialized baseline, not proof of a running cluster's effective setting.

When enabled, this compatibility switch made commands operate on inheritance descendants unless ONLY was written. PostgreSQL 10 removed the switch: modern SQL uses ONLY to exclude descendants, while declarative partition pruning and constraint exclusion govern which child relations are scanned.

Read it together with constraint_exclusion, enable_partition_pruning, search_path, default_table_access_method. Check SHOW and pg_settings on the target server, verify the source and pending_restart fields, and compare workload, logs, and resource metrics before and after any change.

## Tuning advice {#tuning-advice}

> [!TIP]
> **Advice.** These are workload-specific starting points and must be validated with measurements.

| Workload | Guidance |
| --- | --- |
| OLTP | Do not add this retired name to a current OLTP configuration. Translate its intent to the documented successor, test the migration under connection and write concurrency, and remove stale automation that still emits it. |
| OLAP | For an upgrade or analytical estate, inventory every generated configuration before cutover. Map the old control to its successor and compare plans, throughput, WAL, or logging behavior rather than assuming the old numeric value is portable. |
| Small nodes | Delete the obsolete override after recording why it existed. On a small node, prefer the successor's default until measurements justify a new value; an unknown startup parameter can otherwise stop the server. |
{.full-width}

## Pigsty {#pigsty}

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG9.6; 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 | — | — |
{.full-width}

> [!CAUTION]
> **Advice — pending human review.** Fact from the current Pigsty template projection: OLTP: PG9.0–9.6 unmodified; OLAP: PG9.0–9.6 unmodified; CRIT: PG9.0–9.6 unmodified; TINY: PG9.0–9.6 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Treating the measured boot_val for sql_inheritance as proof of the effective value on an initialized or managed cluster.
- Applying a change as though it were immediate while pg_settings reports user context.
- Changing this setting in isolation without checking the linked limits, observability, and rollback path.
- Copying the removed name into a modern postgresql.conf instead of migrating to its documented successor.

## Related parameters {#related-parameters}

[`constraint_exclusion`](/parameters/constraint-exclusion/) · [`enable_partition_pruning`](/parameters/enable-partition-pruning/) · [`search_path`](/parameters/search-path/) · [`default_table_access_method`](/parameters/default-table-access-method/)

## References {#references}

- [PostgreSQL 9.6 — sql_inheritance](https://www.postgresql.org/docs/9.6/runtime-config-compatible.html#GUC-SQL-INHERITANCE)
- [Machine-readable GUC export](/data/guc.jsonl)