# checkpoint_warning

> checkpoint_warning — Sets the maximum time before warning if checkpoints triggered by WAL volume happen too frequently. Observed in PG9.0–19 Beta 3; its last measured boot default is 30 s in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.
---

> [!NOTE]
> **Fact — official short description:** “Sets the maximum time before warning if checkpoints triggered by WAL volume happen too frequently.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `integer` | Upstream pg_settings type |
| Context | `sighup` | Takes effect after configuration reload |
| Unit | `s` | Raw unit |
| Range | `0` – `2147483647` | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Write-Ahead Log / Checkpoints | Upstream classification |
| Latest boot value | `30` | 30 s |
{.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 | `30` | `s` | 30 s |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

Sets the maximum time before warning if checkpoints triggered by WAL volume happen too frequently. A configuration reload applies a new value; existing work already in flight is not retroactively changed.

This parameter only emits a log warning when WAL-volume checkpoints occur closer together than the threshold. It does not delay checkpoints; frequent warnings normally point to max_wal_size being too small for the WAL generation rate.

Monitor and change checkpoint_warning together with checkpoint_flush_after, checkpoint_timeout, checkpoint_completion_target. Validate on the relevant server role and real workload, then use its sighup context to choose session change, reload, or restart; a historical boot default is not the current effective value.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Establish durability and recovery objectives first, then tune checkpoint_warning from WAL rate, flush latency, checkpoints, and peak pg_wal usage. Validate every change with crash/recovery and archive monitoring. |
| OLAP | Provision WAL, archive bandwidth, and recovery I/O for bulk-load peaks. Coordinate load pacing and checkpoints when reducing spikes; never break the recovery chain for throughput. |
| Small nodes | Start from safe defaults or the measured Pigsty value and set explicit alerts for limited disk capacity. Do not disable durability or break the recovery chain merely to save modest I/O. |
{.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}

- Treating the warning threshold as a control that delays or throttles checkpoints.
- Setting zero and silencing evidence of WAL-volume checkpoints.
- Raising the threshold instead of investigating WAL rate, max_wal_size, and requested-checkpoint frequency.
- Setting checkpoint_warning above checkpoint_timeout and expecting time-based checkpoints to produce this warning.

## Related parameters {#related-parameters}

[`checkpoint_flush_after`](/parameters/checkpoint-flush-after/) · [`checkpoint_timeout`](/parameters/checkpoint-timeout/) · [`checkpoint_completion_target`](/parameters/checkpoint-completion-target/) · [`max_wal_size`](/parameters/max-wal-size/) · [`min_wal_size`](/parameters/min-wal-size/) · [`archive_cleanup_command`](/parameters/archive-cleanup-command/)

## References {#references}

- [PostgreSQL 19 Beta 3 — checkpoint_warning](https://www.postgresql.org/docs/19/runtime-config-wal.html#GUC-CHECKPOINT-WARNING)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)