# tcp_keepalives_idle

> tcp_keepalives_idle is the PostgreSQL setting that defines the interval between issuing TCP keepalives.
---

> [!NOTE]
> **Fact — official short description:** “Time between issuing TCP keepalives.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `integer` | Upstream pg_settings type |
| Context | `user` | Settable by an ordinary user |
| Unit | `s` | Raw unit |
| Range | `0` – `2147483647` | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Connections and Authentication / TCP Settings | Upstream classification |
| Latest boot value | `0` | 0 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 | `0` | `s` | 0 s |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

tcp_keepalives_idle defines the interval between issuing TCP keepalives. 0 means use the system default. It determines how long an otherwise idle TCP connection waits before the first keepalive probe; zero selects the operating-system default.

tcp_keepalives_idle 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.

The effective failure window is derived from tcp_keepalives_idle, tcp_keepalives_interval, and tcp_keepalives_count, subject to operating-system support and any shorter network-device timeout.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Choose tcp_keepalives_idle with the other keepalive controls so total failure-detection time fits load-balancer, failover, and retry budgets. Confirm the operating system implements the requested socket option. |
| OLAP | Long analytical connections need keepalive timing shorter than intervening network idle expiry but not so aggressive that transient loss aborts healthy jobs. |
| Small nodes | Use operating-system defaults unless a measured network failure mode requires an override; tune the complete idle/interval/count tuple, not tcp_keepalives_idle alone. |
{.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}

- Changing tcp_keepalives_idle in one session and assuming role defaults, database defaults, or other pooled sessions changed with it.
- Tuning one keepalive component without calculating the full idle-plus-retransmit failure window.
- Assuming PostgreSQL's requested value overrides unsupported platforms or a shorter firewall and load-balancer idle policy.
- Choosing a value longer than the network device's idle timeout and never getting a useful probe first.

## Related parameters {#related-parameters}

[`tcp_keepalives_interval`](/parameters/tcp-keepalives-interval/) · [`tcp_keepalives_count`](/parameters/tcp-keepalives-count/) · [`tcp_user_timeout`](/parameters/tcp-user-timeout/) · [`client_connection_check_interval`](/parameters/client-connection-check-interval/) · [`authentication_timeout`](/parameters/authentication-timeout/)

## References {#references}

- [PostgreSQL 19 Beta 3 — tcp_keepalives_idle](https://www.postgresql.org/docs/19/runtime-config-connection.html#GUC-TCP-KEEPALIVES-IDLE)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)