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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>55.9. 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="55.8. Error and Notice Message Fields" /><link rel="next" href="protocol-changes.html" title="55.10. Summary of Changes since Protocol 2.0" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">55.9. Logical Replication Message Formats</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="protocol-error-fields.html" title="55.8. Error and Notice Message Fields">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="protocol.html" title="Chapter 55. Frontend/Backend Protocol">Up</a></td><th width="60%" align="center">Chapter 55. Frontend/Backend Protocol</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="protocol-changes.html" title="55.10. Summary of Changes since Protocol 2.0">Next</a></td></tr></table><hr /></div><div class="sect1" id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">55.9. Logical Replication Message Formats <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS" class="id_link">#</a></h2></div></div></div><p>
This section describes the detailed format of each logical replication
message. These messages are either returned by the replication slot SQL
interface or are sent by a walsender. In the case of a walsender, they are
encapsulated inside replication protocol WAL messages as described in
<a class="xref" href="protocol-replication.html" title="55.4. Streaming Replication Protocol">Section 55.4</a>, and generally obey the same message
flow as physical replication.
</p><div class="variablelist"><dl class="variablelist"><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-BEGIN"><span class="term">Begin</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-BEGIN" class="id_link">#</a></dt><dd><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 (XLogRecPtr)</span></dt><dd><p>
The final LSN of the transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</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 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-MESSAGE"><span class="term">Message</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-MESSAGE" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('M')</span></dt><dd><p>
Identifies the message as a logical decoding message.
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int8</span></dt><dd><p>
Flags; Either 0 for no flags or 1 if the logical decoding
message is transactional.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the logical decoding message.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The prefix of the logical decoding message.
</p></dd><dt><span class="term">Int32</span></dt><dd><p>
Length of the content.
</p></dd><dt><span class="term">Byte<em class="replaceable"><code>n</code></em></span></dt><dd><p>
The content of the logical decoding message.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-COMMIT"><span class="term">Commit</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-COMMIT" class="id_link">#</a></dt><dd><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(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the commit.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</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></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-ORIGIN"><span class="term">Origin</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-ORIGIN" class="id_link">#</a></dt><dd><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 (XLogRecPtr)</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>
Note that there can be multiple Origin messages inside a single transaction.
</p></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-RELATION"><span class="term">Relation</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-RELATION" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int32 (Oid)</span></dt><dd><p>
OID 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 included in
the publication (except generated columns):
</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 (Oid)</span></dt><dd><p>
OID 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></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TYPE"><span class="term">Type</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TYPE" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int32 (Oid)</span></dt><dd><p>
OID 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></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-INSERT"><span class="term">Insert</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-INSERT" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int32 (Oid)</span></dt><dd><p>
OID 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></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-UPDATE"><span class="term">Update</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-UPDATE" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int32 (Oid)</span></dt><dd><p>
OID 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>
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 id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-DELETE"><span class="term">Delete</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-DELETE" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</p></dd><dt><span class="term">Int32 (Oid)</span></dt><dd><p>
OID 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 an old tuple.
This field is present if the table in which the delete
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>
The Delete message may contain either a 'K' message part or an 'O' message part,
but never both of them.
</p></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TRUNCATE"><span class="term">Truncate</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TRUNCATE" class="id_link">#</a></dt><dd><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 (TransactionId)</span></dt><dd><p>
Xid of the transaction (only present for streamed transactions).
This field is available since protocol version 2.
</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 (Oid)</span></dt><dd><p>
OID of the relation corresponding to the ID in the relation
message. This field is repeated for each relation.
</p></dd></dl></div></dd></dl></div><p>
The following messages (Stream Start, Stream Stop, Stream Commit, and
Stream Abort) are available since protocol version 2.
</p><div class="variablelist"><dl class="variablelist"><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-START"><span class="term">Stream Start</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-START" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('S')</span></dt><dd><p>
Identifies the message as a stream start message.
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">Int8</span></dt><dd><p>
A value of 1 indicates this is the first stream segment for
this XID, 0 for any other stream segment.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-STOP"><span class="term">Stream Stop</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-STOP" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('E')</span></dt><dd><p>
Identifies the message as a stream stop message.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-COMMIT"><span class="term">Stream Commit</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-COMMIT" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('c')</span></dt><dd><p>
Identifies the message as a stream commit message.
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">Int8(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the commit.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</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></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-ABORT"><span class="term">Stream Abort</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-ABORT" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('A')</span></dt><dd><p>
Identifies the message as a stream abort message.
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the subtransaction (will be same as xid of the transaction for top-level
transactions).
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the abort. This field is available since protocol version
4.
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Abort timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01). This field is
available since protocol version 4.
</p></dd></dl></div></dd></dl></div><p>
The following messages (Begin Prepare, Prepare, Commit Prepared, Rollback Prepared, Stream Prepare)
are available since protocol version 3.
</p><div class="variablelist"><dl class="variablelist"><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-BEGIN-PREPARE"><span class="term">Begin Prepare</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-BEGIN-PREPARE" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('b')</span></dt><dd><p>
Identifies the message as the beginning of a prepared transaction message.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the prepare.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the prepared transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Prepare timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01).
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The user defined GID of the prepared transaction.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-PREPARE"><span class="term">Prepare</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-PREPARE" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('P')</span></dt><dd><p>
Identifies the message as a prepared transaction message.
</p></dd><dt><span class="term">Int8(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the prepare.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the prepared transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Prepare timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01).
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The user defined GID of the prepared transaction.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-COMMIT-PREPARED"><span class="term">Commit Prepared</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-COMMIT-PREPARED" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('K')</span></dt><dd><p>
Identifies the message as the commit of a prepared transaction message.
</p></dd><dt><span class="term">Int8(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the commit of the prepared transaction.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the commit of the prepared transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</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 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The user defined GID of the prepared transaction.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-ROLLBACK-PREPARED"><span class="term">Rollback Prepared</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-ROLLBACK-PREPARED" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('r')</span></dt><dd><p>
Identifies the message as the rollback of a prepared transaction message.
</p></dd><dt><span class="term">Int8(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the prepared transaction.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the rollback of the prepared transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Prepare timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01).
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Rollback timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01).
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The user defined GID of the prepared transaction.
</p></dd></dl></div></dd><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-PREPARE"><span class="term">Stream Prepare</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-STREAM-PREPARE" class="id_link">#</a></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('p')</span></dt><dd><p>
Identifies the message as a stream prepared transaction message.
</p></dd><dt><span class="term">Int8(0)</span></dt><dd><p>
Flags; currently unused.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The LSN of the prepare.
</p></dd><dt><span class="term">Int64 (XLogRecPtr)</span></dt><dd><p>
The end LSN of the prepared transaction.
</p></dd><dt><span class="term">Int64 (TimestampTz)</span></dt><dd><p>
Prepare timestamp of the transaction. The value is in number
of microseconds since PostgreSQL epoch (2000-01-01).
</p></dd><dt><span class="term">Int32 (TransactionId)</span></dt><dd><p>
Xid of the transaction.
</p></dd><dt><span class="term">String</span></dt><dd><p>
The user defined GID of the prepared transaction.
</p></dd></dl></div></dd></dl></div><p>
The following message parts are shared by the above messages.
</p><div class="variablelist"><dl class="variablelist"><dt id="PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TUPLEDATA"><span class="term">TupleData</span> <a href="#PROTOCOL-LOGICALREP-MESSAGE-FORMATS-TUPLEDATA" class="id_link">#</a></dt><dd><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 (except generated columns):
</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></dl></div><p>
Or
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Byte1('b')</span></dt><dd><p>
Identifies the data as binary 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, either in binary or in text format.
(As specified in the preceding format byte).
<em class="replaceable"><code>n</code></em> is the above length.
</p></dd></dl></div><p>
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