pg_logical_emit_message() — PostgreSQL system administration function

pg_logical_emit_message(): emit a textual logical decoding message. PostgreSQL system administration functions — signature, volatility, version applicability and an illustrative example.

The Sev-1 Admin
The Sev-1 Admin  ·  2 min read

Summary

pg_logical_emit_message is a PostgreSQL built-in function in the System Administration Functions group. PostgreSQL’s system catalog (pg_proc) describes it as: “emit a textual logical decoding message”.

Signature

pg_logical_emit_message has 2 documented overloaded forms:

pg_logical_emit_message(boolean, text, text, boolean) → pg_lsn
pg_logical_emit_message(boolean, text, bytea, boolean) → pg_lsn

Argument and return types are taken from the pg_proc catalog; internal type names are shown using their readable SQL spellings (for example int4 is shown as integer). (Derived from the catalog — see the linked reference for the canonical documentation.)

Classification

  • Category: System Administration Functions
  • Kind: Function
  • Volatility: VOLATILE — Marked VOLATILE — its result can change even within a single statement (for example, it may depend on time, sequences or the current session).
  • Returns: pg_lsn

Example

Illustrative form (replace placeholder values with your own data):

SELECT pg_logical_emit_message(true, 'abc', 'abc', true);

The example above is illustrative and is meant to show calling syntax only; consult the linked PostgreSQL documentation for exact semantics, edge cases and accepted argument combinations.

Version applicability

pg_logical_emit_message is present across the surveyed releases (PostgreSQL 15, 16, 17, 18). On older major versions, behaviour may differ in detail — always check the documentation for the version you run.

Related & references

Reference: PostgreSQL documentation — System Administration Functions.