in_hot_standby

Definition PG 18 manual

Reports whether the server is currently in hot standby mode. When this is on, all transactions are forced to be read-only. Within a session, this can change only if the server is promoted to be primary. See Section 26.4 for more information.

How it works

Shows whether hot standby is currently active. It is read-only and cannot be changed with SET or configuration-file edits.

It changes as recovery enters or leaves hot-standby operation and is intended for feature detection by SQL code.

Interpret it with hot_standby, max_standby_streaming_delay, hot_standby_feedback. Applications and operations tooling may read in_hot_standby for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences.

Operational considerations

Trying to change read-only in_hot_standby with SET or a configuration file.

Assuming every cluster, database, or vendor build reports the same value.

Ignoring the value in file-format or feature-compatibility checks.

Treating reported metadata as a performance target instead of an environment fact.

Workload guidance

OLAP: Not tunable. Use in_hot_standby to verify format, build, or resource assumptions on analytical nodes and keep every read/write candidate compatible.

OLTP: Not tunable. Record in_hot_standby as a deployment/capability fact; if it is unexpected, fix the binary, initdb, or database-creation process rather than trying SET.

SMALL: Not tunable. Preserve it in inventory and incident reports; do not custom-build or rebuild merely to change it without a demonstrated compatibility need.