<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>53.9. Logical Replication Message Formats</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="protocol-error-fields.html" title="53.8. Error and Notice Message Fields" /><link rel="next" href="protocol-changes.html" title="53.10. Summary of Changes since Protocol 2.0" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">53.9. Logical Replication Message Formats</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="protocol-error-fields.html" title="53.8. Error and Notice Message Fields">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="protocol.html" title="Chapter 53. Frontend/Backend Protocol">Up</a></td><th width="60%" align="center">Chapter 53. Frontend/Backend Protocol</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="protocol-changes.html" title="53.10. Summary of Changes since Protocol 2.0">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">53.9. Logical Replication Message Formats</h2></div></div></div><p> This section describes the detailed format of each logical replication message. These messages are returned either by the replication slot SQL interface or are sent by a walsender. In case of a walsender they are encapsulated inside the replication protocol WAL messages as described in <a class="xref" href="protocol-replication.html" title="53.4. Streaming Replication Protocol">Section 53.4</a> and generally obey same message flow as physical replication. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Begin </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('B') </span></dt><dd><p> Identifies the message as a begin message. </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> The final LSN of the transaction. </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> Commit timestamp of the transaction. The value is in number of microseconds since PostgreSQL epoch (2000-01-01). </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> Xid of the transaction. </p></dd></dl></div><p> </p></dd><dt><span class="term"> Commit </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('C') </span></dt><dd><p> Identifies the message as a commit message. </p></dd><dt><span class="term"> Int8 </span></dt><dd><p> Flags; currently unused (must be 0). </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> The LSN of the commit. </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> The end LSN of the transaction. </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> Commit timestamp of the transaction. The value is in number of microseconds since PostgreSQL epoch (2000-01-01). </p></dd></dl></div><p> </p></dd><dt><span class="term"> Origin </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('O') </span></dt><dd><p> Identifies the message as an origin message. </p></dd><dt><span class="term"> Int64 </span></dt><dd><p> The LSN of the commit on the origin server. </p></dd><dt><span class="term"> String </span></dt><dd><p> Name of the origin. </p></dd></dl></div><p> </p><p> Note that there can be multiple Origin messages inside a single transaction. </p></dd><dt><span class="term"> Relation </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('R') </span></dt><dd><p> Identifies the message as a relation message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the relation. </p></dd><dt><span class="term"> String </span></dt><dd><p> Namespace (empty string for <code class="literal">pg_catalog</code>). </p></dd><dt><span class="term"> String </span></dt><dd><p> Relation name. </p></dd><dt><span class="term"> Int8 </span></dt><dd><p> Replica identity setting for the relation (same as <code class="structfield">relreplident</code> in <code class="structname">pg_class</code>). </p></dd><dt><span class="term"> Int16 </span></dt><dd><p> Number of columns. </p></dd></dl></div><p> Next, the following message part appears for each column: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Int8 </span></dt><dd><p> Flags for the column. Currently can be either 0 for no flags or 1 which marks the column as part of the key. </p></dd><dt><span class="term"> String </span></dt><dd><p> Name of the column. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the column's data type. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> Type modifier of the column (<code class="structfield">atttypmod</code>). </p></dd></dl></div><p> </p></dd><dt><span class="term"> Type </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('Y') </span></dt><dd><p> Identifies the message as a type message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the data type. </p></dd><dt><span class="term"> String </span></dt><dd><p> Namespace (empty string for <code class="literal">pg_catalog</code>). </p></dd><dt><span class="term"> String </span></dt><dd><p> Name of the data type. </p></dd></dl></div><p> </p></dd><dt><span class="term"> Insert </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('I') </span></dt><dd><p> Identifies the message as an insert message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the relation corresponding to the ID in the relation message. </p></dd><dt><span class="term"> Byte1('N') </span></dt><dd><p> Identifies the following TupleData message as a new tuple. </p></dd><dt><span class="term"> TupleData </span></dt><dd><p> TupleData message part representing the contents of new tuple. </p></dd></dl></div><p> </p></dd><dt><span class="term"> Update </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('U') </span></dt><dd><p> Identifies the message as an update message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the relation corresponding to the ID in the relation message. </p></dd><dt><span class="term"> Byte1('K') </span></dt><dd><p> Identifies the following TupleData submessage as a key. This field is optional and is only present if the update changed data in any of the column(s) that are part of the REPLICA IDENTITY index. </p></dd><dt><span class="term"> Byte1('O') </span></dt><dd><p> Identifies the following TupleData submessage as an old tuple. This field is optional and is only present if table in which the update happened has REPLICA IDENTITY set to FULL. </p></dd><dt><span class="term"> TupleData </span></dt><dd><p> TupleData message part representing the contents of the old tuple or primary key. Only present if the previous 'O' or 'K' part is present. </p></dd><dt><span class="term"> Byte1('N') </span></dt><dd><p> Identifies the following TupleData message as a new tuple. </p></dd><dt><span class="term"> TupleData </span></dt><dd><p> TupleData message part representing the contents of a new tuple. </p></dd></dl></div><p> </p><p> The Update message may contain either a 'K' message part or an 'O' message part or neither of them, but never both of them. </p></dd><dt><span class="term"> Delete </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('D') </span></dt><dd><p> Identifies the message as a delete message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the relation corresponding to the ID in the relation message. </p></dd><dt><span class="term"> Byte1('K') </span></dt><dd><p> Identifies the following TupleData submessage as a key. This field is present if the table in which the delete has happened uses an index as REPLICA IDENTITY. </p></dd><dt><span class="term"> Byte1('O') </span></dt><dd><p> Identifies the following TupleData message as a old tuple. This field is present if the table in which the delete has happened has REPLICA IDENTITY set to FULL. </p></dd><dt><span class="term"> TupleData </span></dt><dd><p> TupleData message part representing the contents of the old tuple or primary key, depending on the previous field. </p></dd></dl></div><p> </p><p> The Delete message may contain either a 'K' message part or an 'O' message part, but never both of them. </p></dd><dt><span class="term"> Truncate </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('T') </span></dt><dd><p> Identifies the message as a truncate message. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> Number of relations </p></dd><dt><span class="term"> Int8 </span></dt><dd><p> Option bits for <code class="command">TRUNCATE</code>: 1 for <code class="literal">CASCADE</code>, 2 for <code class="literal">RESTART IDENTITY</code> </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> ID of the relation corresponding to the ID in the relation message. This field is repeated for each relation. </p></dd></dl></div><p> </p></dd></dl></div><p> The following message parts are shared by the above messages. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> TupleData </span></dt><dd><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Int16 </span></dt><dd><p> Number of columns. </p></dd></dl></div><p> Next, one of the following submessages appears for each column: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('n') </span></dt><dd><p> Identifies the data as NULL value. </p></dd></dl></div><p> Or </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('u') </span></dt><dd><p> Identifies unchanged TOASTed value (the actual value is not sent). </p></dd></dl></div><p> Or </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> Byte1('t') </span></dt><dd><p> Identifies the data as text formatted value. </p></dd><dt><span class="term"> Int32 </span></dt><dd><p> Length of the column value. </p></dd><dt><span class="term"> Byte<em class="replaceable"><code>n</code></em> </span></dt><dd><p> The value of the column, in text format. (A future release might support additional formats.) <em class="replaceable"><code>n</code></em> is the above length. </p></dd></dl></div><p> </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="protocol-error-fields.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="protocol.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="protocol-changes.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">53.8. Error and Notice Message Fields </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 53.10. Summary of Changes since Protocol 2.0</td></tr></table></div></body></html>