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  1. <?xml version="1.0" encoding="UTF-8" standalone="no"?>

  2. <!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>52.9. 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 V1.79.1" /><link rel="prev" href="protocol-error-fields.html" title="52.8. Error and Notice Message Fields" /><link rel="next" href="protocol-changes.html" title="52.10. 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">52.9. Logical Replication Message Formats</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="protocol-error-fields.html" title="52.8. Error and Notice Message Fields">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="protocol.html" title="Chapter 52. Frontend/Backend Protocol">Up</a></td><th width="60%" align="center">Chapter 52. Frontend/Backend Protocol</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="protocol-changes.html" title="52.10. 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">52.9. Logical Replication Message Formats</h2></div></div></div><p>

  3. This section describes the detailed format of each logical replication message.

  4. These messages are returned either by the replication slot SQL interface or are

  5. sent by a walsender. In case of a walsender they are encapsulated inside the replication

  6. protocol WAL messages as described in <a class="xref" href="protocol-replication.html" title="52.4. Streaming Replication Protocol">Section 52.4</a>

  7. and generally obey same message flow as physical replication.

  8. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  9. Begin

  10. </span></dt><dd><p>

  11. 

  12. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  13.         Byte1('B')

  14. </span></dt><dd><p>

  15.                 Identifies the message as a begin message.

  16. </p></dd><dt><span class="term">

  17.         Int64

  18. </span></dt><dd><p>

  19.                 The final LSN of the transaction.

  20. </p></dd><dt><span class="term">

  21.         Int64

  22. </span></dt><dd><p>

  23.                 Commit timestamp of the transaction. The value is in number

  24.                 of microseconds since PostgreSQL epoch (2000-01-01).

  25. </p></dd><dt><span class="term">

  26.         Int32

  27. </span></dt><dd><p>

  28.                 Xid of the transaction.

  29. </p></dd></dl></div><p>

  30. </p></dd><dt><span class="term">

  31. Commit

  32. </span></dt><dd><p>

  33. 

  34. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  35.         Byte1('C')

  36. </span></dt><dd><p>

  37.                 Identifies the message as a commit message.

  38. </p></dd><dt><span class="term">

  39.         Int8

  40. </span></dt><dd><p>

  41.                 Flags; currently unused (must be 0).

  42. </p></dd><dt><span class="term">

  43.         Int64

  44. </span></dt><dd><p>

  45.                 The LSN of the commit.

  46. </p></dd><dt><span class="term">

  47.         Int64

  48. </span></dt><dd><p>

  49.                 The end LSN of the transaction.

  50. </p></dd><dt><span class="term">

  51.         Int64

  52. </span></dt><dd><p>

  53.                 Commit timestamp of the transaction. The value is in number

  54.                 of microseconds since PostgreSQL epoch (2000-01-01).

  55. </p></dd></dl></div><p>

  56. </p></dd><dt><span class="term">

  57. Origin

  58. </span></dt><dd><p>

  59. 

  60. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  61.         Byte1('O')

  62. </span></dt><dd><p>

  63.                 Identifies the message as an origin message.

  64. </p></dd><dt><span class="term">

  65.         Int64

  66. </span></dt><dd><p>

  67.                 The LSN of the commit on the origin server.

  68. </p></dd><dt><span class="term">

  69.         String

  70. </span></dt><dd><p>

  71.                 Name of the origin.

  72. </p></dd></dl></div><p>

  73. </p><p>

  74.   Note that there can be multiple Origin messages inside a single transaction.

  75. </p></dd><dt><span class="term">

  76. Relation

  77. </span></dt><dd><p>

  78. 

  79. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  80.         Byte1('R')

  81. </span></dt><dd><p>

  82.                 Identifies the message as a relation message.

  83. </p></dd><dt><span class="term">

  84.         Int32

  85. </span></dt><dd><p>

  86.                 ID of the relation.

  87. </p></dd><dt><span class="term">

  88.         String

  89. </span></dt><dd><p>

  90.                 Namespace (empty string for <code class="literal">pg_catalog</code>).

  91. </p></dd><dt><span class="term">

  92.         String

  93. </span></dt><dd><p>

  94.                 Relation name.

  95. </p></dd><dt><span class="term">

  96.         Int8

  97. </span></dt><dd><p>

  98.                 Replica identity setting for the relation (same as

  99.                 <code class="structfield">relreplident</code> in <code class="structname">pg_class</code>).

  100. </p></dd><dt><span class="term">

  101.         Int16

  102. </span></dt><dd><p>

  103.                 Number of columns.

  104. </p></dd></dl></div><p>

  105.         Next, the following message part appears for each column (except generated columns):

  106. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  107.         Int8

  108. </span></dt><dd><p>

  109.                 Flags for the column. Currently can be either 0 for no flags

  110.                 or 1 which marks the column as part of the key.

  111. </p></dd><dt><span class="term">

  112.         String

  113. </span></dt><dd><p>

  114.                 Name of the column.

  115. </p></dd><dt><span class="term">

  116.         Int32

  117. </span></dt><dd><p>

  118.                 ID of the column's data type.

  119. </p></dd><dt><span class="term">

  120.         Int32

  121. </span></dt><dd><p>

  122.                 Type modifier of the column (<code class="structfield">atttypmod</code>).

  123. </p></dd></dl></div><p>

  124. </p></dd><dt><span class="term">

  125. Type

  126. </span></dt><dd><p>

  127. 

  128. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  129.         Byte1('Y')

  130. </span></dt><dd><p>

  131.                 Identifies the message as a type message.

  132. </p></dd><dt><span class="term">

  133.         Int32

  134. </span></dt><dd><p>

  135.                 ID of the data type.

  136. </p></dd><dt><span class="term">

  137.         String

  138. </span></dt><dd><p>

  139.                 Namespace (empty string for <code class="literal">pg_catalog</code>).

  140. </p></dd><dt><span class="term">

  141.         String

  142. </span></dt><dd><p>

  143.                 Name of the data type.

  144. </p></dd></dl></div><p>

  145. </p></dd><dt><span class="term">

  146. Insert

  147. </span></dt><dd><p>

  148. 

  149. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  150.         Byte1('I')

  151. </span></dt><dd><p>

  152.                 Identifies the message as an insert message.

  153. </p></dd><dt><span class="term">

  154.         Int32

  155. </span></dt><dd><p>

  156.                 ID of the relation corresponding to the ID in the relation

  157.                 message.

  158. </p></dd><dt><span class="term">

  159.         Byte1('N')

  160. </span></dt><dd><p>

  161.                 Identifies the following TupleData message as a new tuple.

  162. </p></dd><dt><span class="term">

  163.         TupleData

  164. </span></dt><dd><p>

  165.                 TupleData message part representing the contents of new tuple.

  166. </p></dd></dl></div><p>

  167. </p></dd><dt><span class="term">

  168. Update

  169. </span></dt><dd><p>

  170. 

  171. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  172.         Byte1('U')

  173. </span></dt><dd><p>

  174.                 Identifies the message as an update message.

  175. </p></dd><dt><span class="term">

  176.         Int32

  177. </span></dt><dd><p>

  178.                 ID of the relation corresponding to the ID in the relation

  179.                 message.

  180. </p></dd><dt><span class="term">

  181.         Byte1('K')

  182. </span></dt><dd><p>

  183.                 Identifies the following TupleData submessage as a key.

  184.                 This field is optional and is only present if

  185.                 the update changed data in any of the column(s) that are

  186.                 part of the REPLICA IDENTITY index.

  187. </p></dd><dt><span class="term">

  188.         Byte1('O')

  189. </span></dt><dd><p>

  190.                 Identifies the following TupleData submessage as an old tuple.

  191.                 This field is optional and is only present if table in which

  192.                 the update happened has REPLICA IDENTITY set to FULL.

  193. </p></dd><dt><span class="term">

  194.         TupleData

  195. </span></dt><dd><p>

  196.                 TupleData message part representing the contents of the old tuple

  197.                 or primary key. Only present if the previous 'O' or 'K' part

  198.                 is present.

  199. </p></dd><dt><span class="term">

  200.         Byte1('N')

  201. </span></dt><dd><p>

  202.                 Identifies the following TupleData message as a new tuple.

  203. </p></dd><dt><span class="term">

  204.         TupleData

  205. </span></dt><dd><p>

  206.                 TupleData message part representing the contents of a new tuple.

  207. </p></dd></dl></div><p>

  208. </p><p>

  209.     The Update message may contain either a 'K' message part or an 'O' message part

  210.     or neither of them, but never both of them.

  211. </p></dd><dt><span class="term">

  212. Delete

  213. </span></dt><dd><p>

  214. 

  215. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  216.         Byte1('D')

  217. </span></dt><dd><p>

  218.                 Identifies the message as a delete message.

  219. </p></dd><dt><span class="term">

  220.         Int32

  221. </span></dt><dd><p>

  222.                 ID of the relation corresponding to the ID in the relation

  223.                 message.

  224. </p></dd><dt><span class="term">

  225.         Byte1('K')

  226. </span></dt><dd><p>

  227.                 Identifies the following TupleData submessage as a key.

  228.                 This field is present if the table in which the delete has

  229.                 happened uses an index as REPLICA IDENTITY.

  230. </p></dd><dt><span class="term">

  231.         Byte1('O')

  232. </span></dt><dd><p>

  233.                 Identifies the following TupleData message as a old tuple.

  234.                 This field is present if the table in which the delete has

  235.                 happened has REPLICA IDENTITY set to FULL.

  236. </p></dd><dt><span class="term">

  237.         TupleData

  238. </span></dt><dd><p>

  239.                 TupleData message part representing the contents of the old tuple

  240.                 or primary key, depending on the previous field.

  241. </p></dd></dl></div><p>

  242. </p><p>

  243.     The Delete message may contain either a 'K' message part or an 'O' message part,

  244.     but never both of them.

  245. </p></dd><dt><span class="term">

  246. Truncate

  247. </span></dt><dd><p>

  248. 

  249. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  250.         Byte1('T')

  251. </span></dt><dd><p>

  252.                 Identifies the message as a truncate message.

  253. </p></dd><dt><span class="term">

  254.         Int32

  255. </span></dt><dd><p>

  256.                 Number of relations

  257. </p></dd><dt><span class="term">

  258.         Int8

  259. </span></dt><dd><p>

  260.                 Option bits for <code class="command">TRUNCATE</code>:

  261.                 1 for <code class="literal">CASCADE</code>, 2 for <code class="literal">RESTART IDENTITY</code>

  262. </p></dd><dt><span class="term">

  263.         Int32

  264. </span></dt><dd><p>

  265.                 ID of the relation corresponding to the ID in the relation

  266.                 message.  This field is repeated for each relation.

  267. </p></dd></dl></div><p>

  268. </p></dd></dl></div><p>

  269. 

  270. The following message parts are shared by the above messages.

  271. 

  272. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  273. TupleData

  274. </span></dt><dd><p>

  275. 

  276. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  277.         Int16

  278. </span></dt><dd><p>

  279.                 Number of columns.

  280. </p></dd></dl></div><p>

  281.         Next, one of the following submessages appears for each column (except generated columns):

  282. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  283.         Byte1('n')

  284. </span></dt><dd><p>

  285.                 Identifies the data as NULL value.

  286. </p></dd></dl></div><p>

  287.         Or

  288. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  289.         Byte1('u')

  290. </span></dt><dd><p>

  291.                 Identifies unchanged TOASTed value (the actual value is not

  292.                 sent).

  293. </p></dd></dl></div><p>

  294.         Or

  295. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  296.         Byte1('t')

  297. </span></dt><dd><p>

  298.                 Identifies the data as text formatted value.

  299. </p></dd><dt><span class="term">

  300.         Int32

  301. </span></dt><dd><p>

  302.                 Length of the column value.

  303. </p></dd><dt><span class="term">

  304.         Byte<em class="replaceable"><code>n</code></em>

  305. </span></dt><dd><p>

  306.                 The value of the column, in text format.  (A future release

  307.                 might support additional formats.)

  308.                 <em class="replaceable"><code>n</code></em> is the above length.

  309. 

  310. </p></dd></dl></div><p>

  311. </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">52.8. 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"> 52.10. Summary of Changes since Protocol 2.0</td></tr></table></div></body></html>
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