# syslog_split_messages

> syslog_split_messages is the PostgreSQL setting that splits messages sent to syslog by lines and to fit into 1024 bytes.
---

> [!NOTE]
> **Fact — official short description:** “Split messages sent to syslog by lines and to fit into 1024 bytes.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `bool` | Upstream pg_settings type |
| Context | `sighup` | Takes effect after configuration reload |
| Unit | — | Raw unit |
| Range | — | Raw limits in the last observed version |
| Enum values | — | — for non-enum types |
| Category | Reporting and Logging / Where to Log | Upstream classification |
| Latest boot value | `on` | on |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG9.6 |
| Present in | PG9.6–19 Beta 3 |
| Removed in | No |
| Introduction commit | [`fc201dfd9505`](https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=fc201dfd95059fd2fef9862a2fd09cfab42c9bf7) — Add syslog_split_messages parameter |
| Commit date | 2016-03-15 |
| Discussion | — |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG9.6–19 Beta 3 | `on` | — | on |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

syslog_split_messages splits messages sent to syslog by lines and to fit into 1024 bytes. When enabled, PostgreSQL splits at line boundaries and the traditional 1024-byte limit; disabling it relies on the receiver to handle multiline or long payloads.

syslog_split_messages is a SIGHUP-context setting: a configuration reload activates the new server value without a restart; subsequent operations that consult it use the refreshed value.

It is active only when syslog appears in log_destination, after which the facility, ident, sequence, splitting, host daemon, and remote receiver jointly define record delivery.

## Tuning advice {#tuning-advice}

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

| Workload | Guidance |
| --- | --- |
| OLTP | Set syslog_split_messages to match the receiving syslog daemon's routing, framing, deduplication, and message-size contract; validate failover and backpressure with the real collector. |
| OLAP | Test syslog_split_messages under bursty analytical messages and multiline plans so splitting or receiver limits do not destroy record boundaries. |
| Small nodes | Prefer the host's established syslog convention for syslog_split_messages; avoid parallel local-file retention unless it has an explicit purpose and size limit. |
{.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: PG9.6–19 Beta 3 unmodified; OLAP: PG9.6–19 Beta 3 unmodified; CRIT: PG9.6–19 Beta 3 unmodified; TINY: PG9.6–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Editing syslog_split_messages without reloading configuration and verifying the effective value and subsequent behavior.
- Changing PostgreSQL framing or identifiers without testing the host daemon and remote receiver as one pipeline.
- Assuming syslog preserves unlimited message size, multiline boundaries, ordering, or repeated records by default.
- Changing syslog_split_messages globally without a rollback plan and a client or operational compatibility test.

## Related parameters {#related-parameters}

[`log_destination`](/parameters/log-destination/) · [`syslog_facility`](/parameters/syslog-facility/) · [`syslog_ident`](/parameters/syslog-ident/) · [`syslog_sequence_numbers`](/parameters/syslog-sequence-numbers/) · [`logging_collector`](/parameters/logging-collector/)

## References {#references}

- [PostgreSQL 19 Beta 3 — syslog_split_messages](https://www.postgresql.org/docs/19/runtime-config-logging.html#GUC-SYSLOG-SPLIT-MESSAGES)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)