# primary_conninfo

> primary_conninfo sets the connection string to be used to connect to the sending server. It is a sighup setting present in PG12–18; the latest recorded boot default is empty.
---

> [!NOTE]
> **Fact — official short description:** “Sets the connection string to be used to connect to the sending server.”

## Identity {#identity}

| Field | Value | Meaning |
| --- | --- | --- |
| Type | `string` | 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 | Replication / Standby Servers | Upstream classification |
| Latest boot value | `""` | empty string |
{.fields meta="-"}

## Lifecycle {#lifecycle}

| Fact | Value |
| --- | --- |
| First observed | PG12 |
| Present in | PG12–19 Beta 3 |
| Removed in | No |
| Introduction commit | [`2dedf4d9a899`](https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=2dedf4d9a899b36d1a8ed29be5efbd1b31a8fe85) — Integrate recovery.conf into postgresql.conf |
| Commit date | 2018-11-25 |
| Discussion | [thread 1](https://www.postgresql.org/message-id/flat/607741529606767@web3g.yandex.ru/) |

## Default history {#default-history}

| Versions | Raw `boot_val` | Unit | Human value |
| --- | --- | --- | --- |
| PG12–19 Beta 3 | `""` | — | empty string |
{.full-width caption="Measured PG9.0–19 Beta 3 boot defaults"}

## How it works {#mechanism}

Sets the connection string to be used to connect to the sending server. A configuration reload applies a new value; existing work already in flight is not retroactively changed.

The WAL receiver uses this libpq connection string to reach an upstream sender. Reloading a changed nonempty value restarts the receiver; credentials should come from a protected passfile where possible, and slot synchronization additionally requires dbname.

Monitor and change primary_conninfo together with max_wal_senders, max_replication_slots, wal_level. 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 | Size primary_conninfo from topology, failover roles, slot/subscription count, and reconnect headroom. Test worst-case primary latency, standby replay, and disk retention before production. |
| OLAP | Read standbys and logical subscribers often see long queries or large transactions. Put explicit bounds on replay/apply and monitor lag, worker saturation, slot restart_lsn, and conflict cancellations. |
| Small nodes | Configure only replication capacity that is actually used. Even a small topology needs bounded timeouts and slot lifecycle; unlimited retention is not reliability. |
{.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: PG12–19 Beta 3 unmodified; OLAP: PG12–19 Beta 3 unmodified; CRIT: PG12–19 Beta 3 unmodified; TINY: PG12–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

## Common pitfalls {#common-pitfalls}

- Embedding a plaintext password in broadly readable configuration or process diagnostics.
- Omitting dbname when slot synchronization needs it.
- Changing upstream identity without coordinating timeline and slot state.
- Changing it on the wrong primary, standby, sender, or subscriber role.
- Watching only configured bytes/time instead of actual lag, slot position, and worker state.

## Related parameters {#related-parameters}

[`max_wal_senders`](/parameters/max-wal-senders/) · [`max_replication_slots`](/parameters/max-replication-slots/) · [`wal_level`](/parameters/wal-level/) · [`wal_sender_timeout`](/parameters/wal-sender-timeout/) · [`max_slot_wal_keep_size`](/parameters/max-slot-wal-keep-size/) · [`primary_slot_name`](/parameters/primary-slot-name/)

## References {#references}

- [PostgreSQL 19 Beta 3 — primary_conninfo](https://www.postgresql.org/docs/19/runtime-config-replication.html#GUC-PRIMARY-CONNINFO)
- [PostgreSQL 19 release notes](https://www.postgresql.org/docs/19/release-19.html)
- [Machine-readable GUC export](/data/guc.jsonl)