# vacuum_freeze_min_age

> vacuum_freeze_min_age — Minimum age at which VACUUM should freeze a table row. Observed in PG9.0–19 Beta 3; its last measured boot default is 50000000 in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
---

> [!NOTE]
> **Fact — official short description:** “Minimum age at which VACUUM should freeze a table row.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `integer` | Upstream pg_settings type |
| Context | `user` | Settable by an ordinary user |
| Unit | — | Raw unit |
| Range | `0` – `1000000000` | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Vacuuming / Freezing | Upstream classification |
| Latest boot value | `50000000` | 50000000 |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG9.0 (research boundary) |
| Present in | PG9.0–19 Beta 3 |
| Removed in | No |
| Introduction commit | Not asserted: predates the PG9.0 research boundary |
| Commit date | — |
| Discussion | — |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG9.0–19 Beta 3 | `50000000` | — | 50000000 |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

Sets the minimum XID age at which VACUUM freezes tuple xmin values. It is a user-context setting, so a session can override it for manual VACUUM.

VACUUM computes an XID freeze cutoff from this age. Lower values freeze XIDs earlier and can repeat work on rows soon updated; higher values defer work. The effective value is capped at half of autovacuum_freeze_max_age.

Track age(relfrozenxid) for tables and age(datfrozenxid) for every database. Interpret this lower cutoff with vacuum_freeze_table_age, autovacuum_freeze_max_age, and vacuum_failsafe_age; the separate vacuum_multixact_freeze_min_age controls MXIDs.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Keep enough distance below autovacuum_freeze_max_age for routine vacuums to advance relfrozenxid. Tune from peak XID consumption and measured vacuum completion, not days on a calendar. |
| OLAP | For append-mostly or static partitions, a lower value during planned VACUUM can freeze XIDs earlier and reduce later aggressive work; verify the extra WAL and scan cost. |
| Small nodes | Keep the upstream default unless XID-age evidence justifies a change. Small databases still share the cluster transaction counter and need every database monitored. |
{.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: PG9.0–19 Beta 3 unmodified; OLAP: PG9.0–19 Beta 3 unmodified; CRIT: PG9.0–19 Beta 3 unmodified; TINY: PG9.0–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Describing the cutoff as an MXID control; MultiXacts use vacuum_multixact_freeze_min_age.
- Converting XID age to time without the measured transaction rate.
- Raising the value so far that routine vacuum loses useful headroom before anti-wraparound work.
- Ignoring per-table autovacuum_freeze_min_age overrides.

## Related parameters {#related-parameters}

[`autovacuum_freeze_max_age`](/parameters/autovacuum-freeze-max-age/) · [`vacuum_freeze_table_age`](/parameters/vacuum-freeze-table-age/) · [`vacuum_failsafe_age`](/parameters/vacuum-failsafe-age/) · [`vacuum_multixact_freeze_min_age`](/parameters/vacuum-multixact-freeze-min-age/) · [`autovacuum`](/parameters/autovacuum/) · [`log_autovacuum_min_duration`](/parameters/log-autovacuum-min-duration/)

## References {#references}

- [PostgreSQL 19 Beta 3 — vacuum_freeze_min_age](https://www.postgresql.org/docs/19/runtime-config-vacuum.html#GUC-VACUUM-FREEZE-MIN-AGE)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)