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RDS for PostgreSQL

Extensions

Logical analysis (pg_decoderbufs)

pg_decoderbufs is a logical decoding extension using the protocol buffer format.

Usage restrictions

pg_decoderbufs supports DML statements (Delete, Update, and Insert) only for logical decoding and the result is presented in the protocol buffer format.

Extension options

Options name	debug-mode
Description	After performing logical decoding, output the decoded result in character mode.
Examples	select * from pg_logical_slot_peek_changes('demo', null, null, 'debug-mode', '1'); select * from pg_logical_slot_get_changes('demo', null, null, 'debug-mode', '1'); tip Refer to the following SQL query for definitions of pg_logical_slot_peek_changes and pg_logical_slot_get_changes functions: select * from pg_proc where proname = 'pg_logical_slot_peek_changes'; select * from pg_proc where proname = 'pg_logical_slot_get_changes';

Mapping relationship

The mapping information between PostgreSQL types and decoderbuf fields is as follows:

PostgreSQL Type OID	Decoderbuf Field
BOOLOID	datum_boolean
INT2OID	datum_int32
INT4OID	datum_int32
INT8OID	datum_int64
OIDOID	datum_int64
FLOAT4OID	datum_float
FLOAT8OID	datum_double
NUMERICOID	datum_double
CHAROID	datum_string
VARCHAROID	datum_string
BPCHAROID	datum_string
TEXTOID	datum_string
JSONOID	datum_string
XMLOID	datum_string
UUIDOID	datum_string
TIMESTAMPOID	datum_string
TIMESTAMPTZOID	datum_string
BYTEAOID	datum_bytes
POINTOID	datum_point
PostGIS geometry	datum_point
PostGIS geography	datum_point

Using extensions

Prerequisites

wal_level is set to logical.

The table for logical analysis has a unique index, primary key, or a specified REPLICA IDENTITY.

Extension usage

Create release and specify logical parsing extension as decoderbufs.

select pg_create_logical_replication_slot('demo', 'decoderbufs');

Enable read/write and view logical parsing in debug-mode mode.

select * from pg_logical_slot_peek_changes('demo', null, null, 'debug-mode', '1');
select * from pg_logical_slot_get_changes('demo', null, null, 'debug-mode', '1');
select * from pg_replication_slots;

Last updated: 2026.01.13 18:44:18