# compute_query_id

> compute_query_id — Enables in-core computation of query identifiers. Observed in PG14–19 Beta 3; its last measured boot default is auto in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
---

> [!NOTE]
> **Fact — official short description:** “Enables in-core computation of query identifiers.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `enum` | Upstream pg_settings type |
| Context | `superuser` | Settable at runtime by a superuser |
| Unit | — | Raw unit |
| Range | — | Raw limits in the last observed version |
| Enum values | `auto`, `regress`, `on`, `off` | — for non-enum types |
| Category | Statistics / Monitoring | Upstream classification |
| Latest boot value | `auto` | auto |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG14 |
| Present in | PG14–19 Beta 3 |
| Removed in | No |
| Introduction commit | [`5fd9dfa5f50e`](https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=5fd9dfa5f50e4906c35133a414ebec5b6d518493) — Move pg_stat_statements query jumbling to core. |
| Commit date | 2021-04-07 |
| Discussion | [thread 1](https://postgr.es/m/20210407125726.tkvjdbw76hxnpwfi@nol) |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG14–19 Beta 3 | `auto` | — | auto |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

compute_query_id controls PostgreSQL's in-core normalized query identifier. The identifier can appear in pg_stat_activity, EXPLAIN, and logs, and is required by pg_stat_statements unless another module computes one.

auto lets a module request in-core computation, on always computes, off prevents it, and regress behaves like auto while suppressing the ID in EXPLAIN for stable regression output.

Only one provider should compute the identifier. An extension with an alternative algorithm must disable the in-core implementation and detect conflicts rather than silently publishing two incompatible IDs. Its superuser context permits an authorized session change without a server restart.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Use auto when pg_stat_statements or another module should request the in-core identifier, and use on only when logs, EXPLAIN, or monitoring require IDs without such a module. Measure query-normalization overhead at peak parse/plan rates. |
| OLAP | auto or on can make long analytical statements easier to correlate across pg_stat_activity, EXPLAIN, and logs. The cost is query-tree normalization and hashing, not clock reads; compare planning CPU on workloads with very large statements. |
| Small nodes | Keep auto unless an external query-ID provider requires off. regress is for stable regression output, not a smaller production setting, and off can remove IDs required by pg_stat_statements. |
{.full-width}

## Pigsty {#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 | — | — |
{.full-width}

> [!CAUTION]
> **Advice — pending human review.** Fact from the current Pigsty template projection: OLTP: PG14–19 Beta 3 unmodified; OLAP: PG14–19 Beta 3 unmodified; CRIT: PG14–19 Beta 3 unmodified; TINY: PG14–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Enabling the in-core provider while an extension also attempts to compute a different query identifier.
- Setting off and silently losing IDs required by pg_stat_statements, logs, or correlation tooling.
- Treating regress as a production optimization rather than a test-output mode.
- Using query IDs as stable cross-major-version or cryptographic identifiers.

## Related parameters {#related-parameters}

[`track_activities`](/parameters/track-activities/) · [`shared_preload_libraries`](/parameters/shared-preload-libraries/) · [`log_line_prefix`](/parameters/log-line-prefix/) · [`track_activity_query_size`](/parameters/track-activity-query-size/)

## References {#references}

- [PostgreSQL 19 Beta 3 — compute_query_id](https://www.postgresql.org/docs/19/runtime-config-statistics.html#GUC-COMPUTE-QUERY-ID)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)