PostgreSQL: Documentation: 18: Chapter 47. Logical Decoding

February 26, 2026: PostgreSQL 18.3, 17.9, 16.13, 15.17, and 14.22 Released! Documentation → PostgreSQL 18 Supported Versions: Current (18) / 17 / 16 / 15 / 14 Development Versions: devel Unsupported versions: 13 / 12 / 11 / 10 / 9.6 / 9.5 / 9.4 Chapter 47. Logical Decoding Prev Up Part V. Server Programming Home Next Chapter 47. Logical Decoding Table of Contents 47.1. Logical Decoding Examples 47.2. Logical Decoding Concepts 47.2.1. Logical Decoding 47.2.2. Replication Slots 47.2.3. Replication Slot Synchronization 47.2.4. Output Plugins 47.2.5. Exported Snapshots 47.3. Streaming Replication Protocol Interface 47.4. Logical Decoding SQL Interface 47.5. System Catalogs Related to Logical Decoding 47.6. Logical Decoding Output Plugins 47.6.1. Initialization Function 47.6.2. Capabilities 47.6.3. Output Modes 47.6.4. Output Plugin Callbacks 47.6.5. Functions for Producing Output 47.7. Logical Decoding Output Writers 47.8. Synchronous Replication Support for Logical Decoding 47.8.1. Overview 47.8.2. Caveats 47.9. Streaming of Large Transactions for Logical Decoding 47.10. Two-phase Commit Support for Logical Decoding PostgreSQL provides infrastructure to stream the modifications performed via SQL to external consumers. This functionality can be used for a variety of purposes, including replication solutions and auditing. Changes are sent out in streams identified by logical replication slots. The format in which those changes are streamed is determined by the output plugin used. An example plugin is provided in the PostgreSQL distribution. Additional plugins can be written to extend the choice of available formats without modifying any core code. Every output plugin has access to each individual new row produced by INSERT and the new row version created by UPDATE. Availability of old row versions for UPDATE and DELETE depends on the configured replica identity (see REPLICA IDENTITY). Changes can be consumed either using the streaming replication protocol (see Section 54.4 and Section 47.3), or by calling functions via SQL (see Section 47.4). It is also possible to write additional methods of consuming the output of a replication slot without modifying core code (see Section 47.7). Prev Up Next Chapter 46. Background Worker Processes Home 47.1. Logical Decoding Examples Submit correction If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.