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<!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 11.5 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>
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