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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>52.7. 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-message-types.html" title="52.6. Message Data Types" /><link rel="next" href="protocol-error-fields.html" title="52.8. Error and Notice Message Fields" /></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">52.7. Message Formats</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="protocol-message-types.html" title="52.6. Message Data Types">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-error-fields.html" title="52.8. Error and Notice Message Fields">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="PROTOCOL-MESSAGE-FORMATS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">52.7. Message Formats</h2></div></div></div><p>

  3. This section describes the detailed format of each message.  Each is marked to

  4. indicate that it can be sent by a frontend (F), a backend (B), or both

  5. (F &amp; B).

  6. Notice that although each message includes a byte count at the beginning,

  7. the message format is defined so that the message end can be found without

  8. reference to the byte count.  This aids validity checking.  (The CopyData

  9. message is an exception, because it forms part of a data stream; the contents

  10. of any individual CopyData message cannot be interpretable on their own.)

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

  12. AuthenticationOk (B)

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

  14. 

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

  16.         Byte1('R')

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

  18.                 Identifies the message as an authentication request.

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

  20.         Int32(8)

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

  22.                 Length of message contents in bytes, including self.

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

  24.         Int32(0)

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

  26.                 Specifies that the authentication was successful.

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

  28. 

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

  30. AuthenticationKerberosV5 (B)

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

  32. 

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

  34.         Byte1('R')

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

  36.                 Identifies the message as an authentication request.

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

  38.         Int32(8)

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

  40.                 Length of message contents in bytes, including self.

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

  42.         Int32(2)

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

  44.                 Specifies that Kerberos V5 authentication is required.

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

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

  47. AuthenticationCleartextPassword (B)

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

  49. 

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

  51.         Byte1('R')

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

  53.                 Identifies the message as an authentication request.

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

  55.         Int32(8)

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

  57.                 Length of message contents in bytes, including self.

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

  59.         Int32(3)

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

  61.                 Specifies that a clear-text password is required.

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

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

  64. AuthenticationMD5Password (B)

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

  66. 

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

  68.         Byte1('R')

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

  70.                 Identifies the message as an authentication request.

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

  72.         Int32(12)

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

  74.                 Length of message contents in bytes, including self.

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

  76.         Int32(5)

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

  78.                 Specifies that an MD5-encrypted password is required.

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

  80.         Byte4

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

  82.                 The salt to use when encrypting the password.

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

  84. 

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

  86. AuthenticationSCMCredential (B)

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

  88. 

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

  90.         Byte1('R')

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

  92.                 Identifies the message as an authentication request.

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

  94.         Int32(8)

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

  96.                 Length of message contents in bytes, including self.

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

  98.         Int32(6)

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

  100.                 Specifies that an SCM credentials message is required.

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

  102. 

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

  104. AuthenticationGSS (B)

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

  106. 

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

  108.         Byte1('R')

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

  110.                 Identifies the message as an authentication request.

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

  112.         Int32(8)

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

  114.                 Length of message contents in bytes, including self.

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

  116.         Int32(7)

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

  118.                 Specifies that GSSAPI authentication is required.

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

  120. 

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

  122. AuthenticationSSPI (B)

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

  124. 

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

  126.         Byte1('R')

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

  128.                 Identifies the message as an authentication request.

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

  130.         Int32(8)

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

  132.                 Length of message contents in bytes, including self.

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

  134.         Int32(9)

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

  136.                 Specifies that SSPI authentication is required.

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

  138. 

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

  140. AuthenticationGSSContinue (B)

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

  142. 

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

  144.         Byte1('R')

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

  146.                 Identifies the message as an authentication request.

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

  148.         Int32

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

  150.                 Length of message contents in bytes, including self.

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

  152.         Int32(8)

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

  154.                 Specifies that this message contains GSSAPI or SSPI data.

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

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

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

  158.                 GSSAPI or SSPI authentication data.

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

  160. 

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

  162. AuthenticationSASL (B)

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

  164. 

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

  166.         Byte1('R')

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

  168.                 Identifies the message as an authentication request.

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

  170.         Int32

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

  172.                 Length of message contents in bytes, including self.

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

  174.         Int32(10)

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

  176.                 Specifies that SASL authentication is required.

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

  178. The message body is a list of SASL authentication mechanisms, in the

  179. server's order of preference. A zero byte is required as terminator after

  180. the last authentication mechanism name. For each mechanism, there is the

  181. following:

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

  183.         String

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

  185.                 Name of a SASL authentication mechanism.

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

  187. 

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

  189. AuthenticationSASLContinue (B)

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

  191. 

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

  193.         Byte1('R')

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

  195.                 Identifies the message as an authentication request.

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

  197.         Int32

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

  199.                 Length of message contents in bytes, including self.

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

  201.         Int32(11)

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

  203.                 Specifies that this message contains a SASL challenge.

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

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

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

  207.                 SASL data, specific to the SASL mechanism being used.

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

  209. 

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

  211. AuthenticationSASLFinal (B)

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

  213. 

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

  215.         Byte1('R')

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

  217.                 Identifies the message as an authentication request.

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

  219.         Int32

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

  221.                 Length of message contents in bytes, including self.

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

  223.         Int32(12)

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

  225.                 Specifies that SASL authentication has completed.

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

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

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

  229.                 SASL outcome "additional data", specific to the SASL mechanism

  230.                 being used.

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

  232. 

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

  234. BackendKeyData (B)

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

  236. 

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

  238.         Byte1('K')

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

  240.                 Identifies the message as cancellation key data.

  241.                 The frontend must save these values if it wishes to be

  242.                 able to issue CancelRequest messages later.

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

  244.         Int32(12)

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

  246.                 Length of message contents in bytes, including self.

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

  248.         Int32

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

  250.                 The process ID of this backend.

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

  252.         Int32

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

  254.                 The secret key of this backend.

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

  256. 

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

  258. Bind (F)

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

  260. 

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

  262.         Byte1('B')

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

  264.                 Identifies the message as a Bind command.

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

  266.         Int32

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

  268.                 Length of message contents in bytes, including self.

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

  270.         String

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

  272.                 The name of the destination portal

  273.                 (an empty string selects the unnamed portal).

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

  275.         String

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

  277.                 The name of the source prepared statement

  278.                 (an empty string selects the unnamed prepared statement).

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

  280.         Int16

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

  282.                 The number of parameter format codes that follow

  283.                 (denoted <em class="replaceable"><code>C</code></em> below).

  284.                 This can be zero to indicate that there are no parameters

  285.                 or that the parameters all use the default format (text);

  286.                 or one, in which case the specified format code is applied

  287.                 to all parameters; or it can equal the actual number of

  288.                 parameters.

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

  290.         Int16[<em class="replaceable"><code>C</code></em>]

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

  292.                 The parameter format codes.  Each must presently be

  293.                 zero (text) or one (binary).

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

  295.         Int16

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

  297.                 The number of parameter values that follow (possibly zero).

  298.                 This must match the number of parameters needed by the query.

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

  300.         Next, the following pair of fields appear for each parameter:

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

  302.         Int32

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

  304.                 The length of the parameter value, in bytes (this count

  305.                 does not include itself).  Can be zero.

  306.                 As a special case, -1 indicates a NULL parameter value.

  307.                 No value bytes follow in the NULL case.

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

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

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

  311.                 The value of the parameter, in the format indicated by the

  312.                 associated format code.

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

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

  315.         After the last parameter, the following fields appear:

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

  317.         Int16

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

  319.                 The number of result-column format codes that follow

  320.                 (denoted <em class="replaceable"><code>R</code></em> below).

  321.                 This can be zero to indicate that there are no result columns

  322.                 or that the result columns should all use the default format

  323.                 (text);

  324.                 or one, in which case the specified format code is applied

  325.                 to all result columns (if any); or it can equal the actual

  326.                 number of result columns of the query.

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

  328.         Int16[<em class="replaceable"><code>R</code></em>]

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

  330.                 The result-column format codes.  Each must presently be

  331.                 zero (text) or one (binary).

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

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

  334. BindComplete (B)

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

  336. 

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

  338.         Byte1('2')

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

  340.                 Identifies the message as a Bind-complete indicator.

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

  342.         Int32(4)

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

  344.                 Length of message contents in bytes, including self.

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

  346. 

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

  348. CancelRequest (F)

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

  350. 

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

  352.         Int32(16)

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

  354.                 Length of message contents in bytes, including self.

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

  356.         Int32(80877102)

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

  358.                 The cancel request code.  The value is chosen to contain

  359.                 <code class="literal">1234</code> in the most significant 16 bits, and <code class="literal">5678</code> in the

  360.                 least significant 16 bits.  (To avoid confusion, this code

  361.                 must not be the same as any protocol version number.)

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

  363.         Int32

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

  365.                 The process ID of the target backend.

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

  367.         Int32

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

  369.                 The secret key for the target backend.

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

  371. 

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

  373. Close (F)

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

  375. 

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

  377.         Byte1('C')

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

  379.                 Identifies the message as a Close command.

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

  381.         Int32

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

  383.                 Length of message contents in bytes, including self.

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

  385.         Byte1

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

  387.                 '<code class="literal">S</code>' to close a prepared statement; or

  388.                 '<code class="literal">P</code>' to close a portal.

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

  390.         String

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

  392.                 The name of the prepared statement or portal to close

  393.                 (an empty string selects the unnamed prepared statement

  394.                 or portal).

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

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

  397. CloseComplete (B)

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

  399. 

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

  401.         Byte1('3')

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

  403.                 Identifies the message as a Close-complete indicator.

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

  405.         Int32(4)

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

  407.                 Length of message contents in bytes, including self.

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

  409. 

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

  411. CommandComplete (B)

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

  413. 

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

  415.         Byte1('C')

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

  417.                 Identifies the message as a command-completed response.

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

  419.         Int32

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

  421.                 Length of message contents in bytes, including self.

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

  423.         String

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

  425.         The command tag.  This is usually a single

  426.         word that identifies which SQL command was completed.

  427.        </p><p>

  428.         For an <code class="command">INSERT</code> command, the tag is

  429.         <code class="literal">INSERT <em class="replaceable"><code>oid</code></em>

  430.         <em class="replaceable"><code>rows</code></em></code>, where

  431.         <em class="replaceable"><code>rows</code></em> is the number of rows

  432.         inserted. <em class="replaceable"><code>oid</code></em> used to be the object ID

  433.         of the inserted row if <em class="replaceable"><code>rows</code></em> was 1

  434.         and the target table had OIDs, but OIDs system columns are

  435.         not supported anymore; therefore <em class="replaceable"><code>oid</code></em>

  436.         is always 0.

  437.        </p><p>

  438.         For a <code class="command">DELETE</code> command, the tag is

  439.         <code class="literal">DELETE <em class="replaceable"><code>rows</code></em></code> where

  440.         <em class="replaceable"><code>rows</code></em> is the number of rows deleted.

  441.        </p><p>

  442.         For an <code class="command">UPDATE</code> command, the tag is

  443.         <code class="literal">UPDATE <em class="replaceable"><code>rows</code></em></code> where

  444.         <em class="replaceable"><code>rows</code></em> is the number of rows updated.

  445.        </p><p>

  446.         For a <code class="command">SELECT</code> or <code class="command">CREATE TABLE AS</code>

  447.         command, the tag is <code class="literal">SELECT <em class="replaceable"><code>rows</code></em></code>

  448.         where <em class="replaceable"><code>rows</code></em> is the number of rows retrieved.

  449.        </p><p>

  450.         For a <code class="command">MOVE</code> command, the tag is

  451.         <code class="literal">MOVE <em class="replaceable"><code>rows</code></em></code> where

  452.         <em class="replaceable"><code>rows</code></em> is the number of rows the

  453.         cursor's position has been changed by.

  454.        </p><p>

  455.         For a <code class="command">FETCH</code> command, the tag is

  456.         <code class="literal">FETCH <em class="replaceable"><code>rows</code></em></code> where

  457.         <em class="replaceable"><code>rows</code></em> is the number of rows that

  458.         have been retrieved from the cursor.

  459.        </p><p>

  460.         For a <code class="command">COPY</code> command, the tag is

  461.         <code class="literal">COPY <em class="replaceable"><code>rows</code></em></code> where

  462.         <em class="replaceable"><code>rows</code></em> is the number of rows copied.

  463.         (Note: the row count appears only in

  464.         <span class="productname">PostgreSQL</span> 8.2 and later.)

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

  466. 

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

  468. CopyData (F &amp; B)

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

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

  471.         Byte1('d')

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

  473.                 Identifies the message as <code class="command">COPY</code> data.

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

  475.         Int32

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

  477.                 Length of message contents in bytes, including self.

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

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

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

  481.                 Data that forms part of a <code class="command">COPY</code> data stream.  Messages sent

  482.                 from the backend will always correspond to single data rows,

  483.                 but messages sent by frontends might divide the data stream

  484.                 arbitrarily.

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

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

  487. CopyDone (F &amp; B)

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

  489. 

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

  491.         Byte1('c')

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

  493.                 Identifies the message as a <code class="command">COPY</code>-complete indicator.

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

  495.         Int32(4)

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

  497.                 Length of message contents in bytes, including self.

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

  499. 

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

  501. CopyFail (F)

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

  503. 

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

  505.         Byte1('f')

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

  507.                 Identifies the message as a <code class="command">COPY</code>-failure indicator.

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

  509.         Int32

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

  511.                 Length of message contents in bytes, including self.

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

  513.         String

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

  515.                 An error message to report as the cause of failure.

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

  517. 

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

  519. CopyInResponse (B)

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

  521. 

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

  523.         Byte1('G')

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

  525.                 Identifies the message as a Start Copy In response.

  526.                 The frontend must now send copy-in data (if not

  527.                 prepared to do so, send a CopyFail message).

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

  529.         Int32

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

  531.                 Length of message contents in bytes, including self.

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

  533.         Int8

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

  535.                 0 indicates the overall <code class="command">COPY</code> format is textual (rows

  536.                 separated by newlines, columns separated by separator

  537.                 characters, etc).

  538.                 1 indicates the overall copy format is binary (similar

  539.                 to DataRow format).

  540.                 See <a class="xref" href="sql-copy.html" title="COPY"><span class="refentrytitle">COPY</span></a>

  541.                 for more information.

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

  543.         Int16

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

  545.                 The number of columns in the data to be copied

  546.                 (denoted <em class="replaceable"><code>N</code></em> below).

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

  548.         Int16[<em class="replaceable"><code>N</code></em>]

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

  550.                 The format codes to be used for each column.

  551.                 Each must presently be zero (text) or one (binary).

  552.                 All must be zero if the overall copy format is textual.

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

  554. 

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

  556. CopyOutResponse (B)

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

  558. 

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

  560.         Byte1('H')

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

  562.                 Identifies the message as a Start Copy Out response.

  563.                 This message will be followed by copy-out data.

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

  565.         Int32

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

  567.                 Length of message contents in bytes, including self.

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

  569.         Int8

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

  571.                 0 indicates the overall <code class="command">COPY</code> format

  572.                 is textual (rows separated by newlines, columns

  573.                 separated by separator characters, etc). 1 indicates

  574.                 the overall copy format is binary (similar to DataRow

  575.                 format). See <a class="xref" href="sql-copy.html" title="COPY"><span class="refentrytitle">COPY</span></a> for more information.

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

  577.         Int16

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

  579.                 The number of columns in the data to be copied

  580.                 (denoted <em class="replaceable"><code>N</code></em> below).

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

  582.         Int16[<em class="replaceable"><code>N</code></em>]

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

  584.                 The format codes to be used for each column.

  585.                 Each must presently be zero (text) or one (binary).

  586.                 All must be zero if the overall copy format is textual.

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

  588. 

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

  590. CopyBothResponse (B)

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

  592. 

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

  594.         Byte1('W')

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

  596.                 Identifies the message as a Start Copy Both response.

  597.                 This message is used only for Streaming Replication.

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

  599.         Int32

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

  601.                 Length of message contents in bytes, including self.

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

  603.         Int8

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

  605.                 0 indicates the overall <code class="command">COPY</code> format

  606.                 is textual (rows separated by newlines, columns

  607.                 separated by separator characters, etc). 1 indicates

  608.                 the overall copy format is binary (similar to DataRow

  609.                 format). See <a class="xref" href="sql-copy.html" title="COPY"><span class="refentrytitle">COPY</span></a> for more information.

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

  611.         Int16

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

  613.                 The number of columns in the data to be copied

  614.                 (denoted <em class="replaceable"><code>N</code></em> below).

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

  616.         Int16[<em class="replaceable"><code>N</code></em>]

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

  618.                 The format codes to be used for each column.

  619.                 Each must presently be zero (text) or one (binary).

  620.                 All must be zero if the overall copy format is textual.

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

  622. 

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

  624. DataRow (B)

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

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

  627.         Byte1('D')

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

  629.                 Identifies the message as a data row.

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

  631.         Int32

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

  633.                 Length of message contents in bytes, including self.

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

  635.         Int16

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

  637.                 The number of column values that follow (possibly zero).

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

  639.         Next, the following pair of fields appear for each column:

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

  641.         Int32

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

  643.                 The length of the column value, in bytes (this count

  644.                 does not include itself).  Can be zero.

  645.                 As a special case, -1 indicates a NULL column value.

  646.                 No value bytes follow in the NULL case.

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

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

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

  650.                 The value of the column, in the format indicated by the

  651.                 associated format code.

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

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

  654. 

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

  656. Describe (F)

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

  658. 

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

  660.         Byte1('D')

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

  662.                 Identifies the message as a Describe command.

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

  664.         Int32

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

  666.                 Length of message contents in bytes, including self.

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

  668.         Byte1

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

  670.                 '<code class="literal">S</code>' to describe a prepared statement; or

  671.                 '<code class="literal">P</code>' to describe a portal.

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

  673.         String

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

  675.                 The name of the prepared statement or portal to describe

  676.                 (an empty string selects the unnamed prepared statement

  677.                 or portal).

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

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

  680. EmptyQueryResponse (B)

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

  682. 

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

  684.         Byte1('I')

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

  686.                 Identifies the message as a response to an empty query string.

  687.                 (This substitutes for CommandComplete.)

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

  689.         Int32(4)

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

  691.                 Length of message contents in bytes, including self.

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

  693. 

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

  695. ErrorResponse (B)

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

  697. 

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

  699.         Byte1('E')

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

  701.                 Identifies the message as an error.

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

  703.         Int32

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

  705.                 Length of message contents in bytes, including self.

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

  707.         The message body consists of one or more identified fields,

  708.         followed by a zero byte as a terminator.  Fields can appear in

  709.         any order.  For each field there is the following:

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

  711.         Byte1

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

  713.                 A code identifying the field type; if zero, this is

  714.                 the message terminator and no string follows.

  715.                 The presently defined field types are listed in

  716.                 <a class="xref" href="protocol-error-fields.html" title="52.8. Error and Notice Message Fields">Section 52.8</a>.

  717.                 Since more field types might be added in future,

  718.                 frontends should silently ignore fields of unrecognized

  719.                 type.

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

  721.         String

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

  723.                 The field value.

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

  725. 

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

  727. Execute (F)

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

  729. 

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

  731.         Byte1('E')

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

  733.                 Identifies the message as an Execute command.

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

  735.         Int32

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

  737.                 Length of message contents in bytes, including self.

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

  739.         String

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

  741.                 The name of the portal to execute

  742.                 (an empty string selects the unnamed portal).

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

  744.         Int32

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

  746.                 Maximum number of rows to return, if portal contains

  747.                 a query that returns rows (ignored otherwise).  Zero

  748.                 denotes <span class="quote">“<span class="quote">no limit</span>”</span>.

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

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

  751. Flush (F)

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

  753. 

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

  755.         Byte1('H')

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

  757.                 Identifies the message as a Flush command.

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

  759.         Int32(4)

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

  761.                 Length of message contents in bytes, including self.

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

  763. 

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

  765. FunctionCall (F)

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

  767. 

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

  769.         Byte1('F')

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

  771.                 Identifies the message as a function call.

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

  773.         Int32

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

  775.                 Length of message contents in bytes, including self.

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

  777.         Int32

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

  779.                 Specifies the object ID of the function to call.

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

  781.         Int16

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

  783.                 The number of argument format codes that follow

  784.                 (denoted <em class="replaceable"><code>C</code></em> below).

  785.                 This can be zero to indicate that there are no arguments

  786.                 or that the arguments all use the default format (text);

  787.                 or one, in which case the specified format code is applied

  788.                 to all arguments; or it can equal the actual number of

  789.                 arguments.

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

  791.         Int16[<em class="replaceable"><code>C</code></em>]

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

  793.                 The argument format codes.  Each must presently be

  794.                 zero (text) or one (binary).

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

  796.         Int16

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

  798.                 Specifies the number of arguments being supplied to the

  799.                 function.

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

  801.         Next, the following pair of fields appear for each argument:

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

  803.         Int32

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

  805.                 The length of the argument value, in bytes (this count

  806.                 does not include itself).  Can be zero.

  807.                 As a special case, -1 indicates a NULL argument value.

  808.                 No value bytes follow in the NULL case.

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

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

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

  812.                 The value of the argument, in the format indicated by the

  813.                 associated format code.

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

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

  816.         After the last argument, the following field appears:

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

  818.         Int16

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

  820.                 The format code for the function result. Must presently be

  821.                 zero (text) or one (binary).

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

  823. 

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

  825. FunctionCallResponse (B)

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

  827. 

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

  829.         Byte1('V')

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

  831.                 Identifies the message as a function call result.

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

  833.         Int32

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

  835.                 Length of message contents in bytes, including self.

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

  837.         Int32

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

  839.                 The length of the function result value, in bytes (this count

  840.                 does not include itself).  Can be zero.

  841.                 As a special case, -1 indicates a NULL function result.

  842.                 No value bytes follow in the NULL case.

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

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

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

  846.                 The value of the function result, in the format indicated by

  847.                 the associated format code.

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

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

  850. 

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

  852. GSSResponse (F)

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

  854. 

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

  856.         Byte1('p')

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

  858.                 Identifies the message as a GSSAPI or SSPI response. Note that

  859.                 this is also used for SASL and password response messages.

  860.                 The exact message type can be deduced from the context.

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

  862.         Int32

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

  864.                 Length of message contents in bytes, including self.

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

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

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

  868.                 GSSAPI/SSPI specific message data.

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

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

  871. NegotiateProtocolVersion (B)

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

  873. 

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

  875.         Byte1('v')

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

  877.                 Identifies the message as a protocol version negotiation

  878.                 message.

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

  880.         Int32

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

  882.                 Length of message contents in bytes, including self.

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

  884.         Int32

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

  886.                 Newest minor protocol version supported by the server

  887.                 for the major protocol version requested by the client.

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

  889.         Int32

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

  891.                 Number of protocol options not recognized by the server.

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

  893.         Then, for protocol option not recognized by the server, there

  894.         is the following:

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

  896.         String

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

  898.                 The option name.

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

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

  901. NoData (B)

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

  903. 

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

  905.         Byte1('n')

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

  907.                 Identifies the message as a no-data indicator.

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

  909.         Int32(4)

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

  911.                 Length of message contents in bytes, including self.

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

  913. 

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

  915. NoticeResponse (B)

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

  917. 

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

  919.         Byte1('N')

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

  921.                 Identifies the message as a notice.

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

  923.         Int32

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

  925.                 Length of message contents in bytes, including self.

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

  927.         The message body consists of one or more identified fields,

  928.         followed by a zero byte as a terminator.  Fields can appear in

  929.         any order.  For each field there is the following:

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

  931.         Byte1

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

  933.                 A code identifying the field type; if zero, this is

  934.                 the message terminator and no string follows.

  935.                 The presently defined field types are listed in

  936.                 <a class="xref" href="protocol-error-fields.html" title="52.8. Error and Notice Message Fields">Section 52.8</a>.

  937.                 Since more field types might be added in future,

  938.                 frontends should silently ignore fields of unrecognized

  939.                 type.

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

  941.         String

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

  943.                 The field value.

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

  945. 

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

  947. NotificationResponse (B)

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

  949. 

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

  951.         Byte1('A')

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

  953.                 Identifies the message as a notification response.

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

  955.         Int32

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

  957.                 Length of message contents in bytes, including self.

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

  959.         Int32

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

  961.                 The process ID of the notifying backend process.

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

  963.         String

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

  965.                 The name of the channel that the notify has been raised on.

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

  967.         String

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

  969.                 The <span class="quote">“<span class="quote">payload</span>”</span> string passed from the notifying process.

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

  971. 

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

  973. ParameterDescription (B)

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

  975. 

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

  977.         Byte1('t')

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

  979.                 Identifies the message as a parameter description.

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

  981.         Int32

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

  983.                 Length of message contents in bytes, including self.

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

  985.         Int16

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

  987.                 The number of parameters used by the statement

  988.                 (can be zero).

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

  990.         Then, for each parameter, there is the following:

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

  992.         Int32

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

  994.                 Specifies the object ID of the parameter data type.

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

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

  997. ParameterStatus (B)

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

  999. 

  1000. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1001.         Byte1('S')

  1002. </span></dt><dd><p>

  1003.                 Identifies the message as a run-time parameter status report.

  1004. </p></dd><dt><span class="term">

  1005.         Int32

  1006. </span></dt><dd><p>

  1007.                 Length of message contents in bytes, including self.

  1008. </p></dd><dt><span class="term">

  1009.         String

  1010. </span></dt><dd><p>

  1011.                 The name of the run-time parameter being reported.

  1012. </p></dd><dt><span class="term">

  1013.         String

  1014. </span></dt><dd><p>

  1015.                 The current value of the parameter.

  1016. </p></dd></dl></div><p>

  1017. </p></dd><dt><span class="term">

  1018. Parse (F)

  1019. </span></dt><dd><p>

  1020. 

  1021. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1022.         Byte1('P')

  1023. </span></dt><dd><p>

  1024.                 Identifies the message as a Parse command.

  1025. </p></dd><dt><span class="term">

  1026.         Int32

  1027. </span></dt><dd><p>

  1028.                 Length of message contents in bytes, including self.

  1029. </p></dd><dt><span class="term">

  1030.         String

  1031. </span></dt><dd><p>

  1032.                 The name of the destination prepared statement

  1033.                 (an empty string selects the unnamed prepared statement).

  1034. </p></dd><dt><span class="term">

  1035.         String

  1036. </span></dt><dd><p>

  1037.                 The query string to be parsed.

  1038. </p></dd><dt><span class="term">

  1039.         Int16

  1040. </span></dt><dd><p>

  1041.                 The number of parameter data types specified

  1042.                 (can be zero).  Note that this is not an indication of

  1043.                 the number of parameters that might appear in the

  1044.                 query string, only the number that the frontend wants to

  1045.                 prespecify types for.

  1046. </p></dd></dl></div><p>

  1047.         Then, for each parameter, there is the following:

  1048. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1049.         Int32

  1050. </span></dt><dd><p>

  1051.                 Specifies the object ID of the parameter data type.

  1052.                 Placing a zero here is equivalent to leaving the type

  1053.                 unspecified.

  1054. </p></dd></dl></div><p>

  1055. </p></dd><dt><span class="term">

  1056. ParseComplete (B)

  1057. </span></dt><dd><p>

  1058. 

  1059. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1060.         Byte1('1')

  1061. </span></dt><dd><p>

  1062.                 Identifies the message as a Parse-complete indicator.

  1063. </p></dd><dt><span class="term">

  1064.         Int32(4)

  1065. </span></dt><dd><p>

  1066.                 Length of message contents in bytes, including self.

  1067. </p></dd></dl></div><p>

  1068. 

  1069. </p></dd><dt><span class="term">

  1070. PasswordMessage (F)

  1071. </span></dt><dd><p>

  1072. 

  1073. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1074.         Byte1('p')

  1075. </span></dt><dd><p>

  1076.                 Identifies the message as a password response. Note that

  1077.                 this is also used for GSSAPI, SSPI and SASL response messages.

  1078.                 The exact message type can be deduced from the context.

  1079. </p></dd><dt><span class="term">

  1080.         Int32

  1081. </span></dt><dd><p>

  1082.                 Length of message contents in bytes, including self.

  1083. </p></dd><dt><span class="term">

  1084.         String

  1085. </span></dt><dd><p>

  1086.                 The password (encrypted, if requested).

  1087. </p></dd></dl></div><p>

  1088. </p></dd><dt><span class="term">

  1089. PortalSuspended (B)

  1090. </span></dt><dd><p>

  1091. 

  1092. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1093.         Byte1('s')

  1094. </span></dt><dd><p>

  1095.                 Identifies the message as a portal-suspended indicator.

  1096.                 Note this only appears if an Execute message's row-count limit

  1097.                 was reached.

  1098. </p></dd><dt><span class="term">

  1099.         Int32(4)

  1100. </span></dt><dd><p>

  1101.                 Length of message contents in bytes, including self.

  1102. </p></dd></dl></div><p>

  1103. 

  1104. </p></dd><dt><span class="term">

  1105. Query (F)

  1106. </span></dt><dd><p>

  1107. 

  1108. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1109.         Byte1('Q')

  1110. </span></dt><dd><p>

  1111.                 Identifies the message as a simple query.

  1112. </p></dd><dt><span class="term">

  1113.         Int32

  1114. </span></dt><dd><p>

  1115.                 Length of message contents in bytes, including self.

  1116. </p></dd><dt><span class="term">

  1117.         String

  1118. </span></dt><dd><p>

  1119.                 The query string itself.

  1120. </p></dd></dl></div><p>

  1121. 

  1122. </p></dd><dt><span class="term">

  1123. ReadyForQuery (B)

  1124. </span></dt><dd><p>

  1125. 

  1126. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1127.         Byte1('Z')

  1128. </span></dt><dd><p>

  1129.                 Identifies the message type.  ReadyForQuery is sent

  1130.                 whenever the backend is ready for a new query cycle.

  1131. </p></dd><dt><span class="term">

  1132.         Int32(5)

  1133. </span></dt><dd><p>

  1134.                 Length of message contents in bytes, including self.

  1135. </p></dd><dt><span class="term">

  1136.         Byte1

  1137. </span></dt><dd><p>

  1138.                 Current backend transaction status indicator.

  1139.                 Possible values are '<code class="literal">I</code>' if idle (not in

  1140.                 a transaction block); '<code class="literal">T</code>' if in a transaction

  1141.                 block; or '<code class="literal">E</code>' if in a failed transaction

  1142.                 block (queries will be rejected until block is ended).

  1143. </p></dd></dl></div><p>

  1144. 

  1145. </p></dd><dt><span class="term">

  1146. RowDescription (B)

  1147. </span></dt><dd><p>

  1148. 

  1149. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1150.         Byte1('T')

  1151. </span></dt><dd><p>

  1152.                 Identifies the message as a row description.

  1153. </p></dd><dt><span class="term">

  1154.         Int32

  1155. </span></dt><dd><p>

  1156.                 Length of message contents in bytes, including self.

  1157. </p></dd><dt><span class="term">

  1158.         Int16

  1159. </span></dt><dd><p>

  1160.                 Specifies the number of fields in a row (can be zero).

  1161. </p></dd></dl></div><p>

  1162.         Then, for each field, there is the following:

  1163. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1164.         String

  1165. </span></dt><dd><p>

  1166.                 The field name.

  1167. </p></dd><dt><span class="term">

  1168.         Int32

  1169. </span></dt><dd><p>

  1170.                 If the field can be identified as a column of a specific

  1171.                 table, the object ID of the table; otherwise zero.

  1172. </p></dd><dt><span class="term">

  1173.         Int16

  1174. </span></dt><dd><p>

  1175.                 If the field can be identified as a column of a specific

  1176.                 table, the attribute number of the column; otherwise zero.

  1177. </p></dd><dt><span class="term">

  1178.         Int32

  1179. </span></dt><dd><p>

  1180.                 The object ID of the field's data type.

  1181. </p></dd><dt><span class="term">

  1182.         Int16

  1183. </span></dt><dd><p>

  1184.                 The data type size (see <code class="varname">pg_type.typlen</code>).

  1185.                 Note that negative values denote variable-width types.

  1186. </p></dd><dt><span class="term">

  1187.         Int32

  1188. </span></dt><dd><p>

  1189.                 The type modifier (see <code class="varname">pg_attribute.atttypmod</code>).

  1190.                 The meaning of the modifier is type-specific.

  1191. </p></dd><dt><span class="term">

  1192.         Int16

  1193. </span></dt><dd><p>

  1194.                 The format code being used for the field.  Currently will

  1195.                 be zero (text) or one (binary).  In a RowDescription

  1196.                 returned from the statement variant of Describe, the

  1197.                 format code is not yet known and will always be zero.

  1198. </p></dd></dl></div><p>

  1199. 

  1200. </p></dd><dt><span class="term">

  1201. SASLInitialResponse (F)

  1202. </span></dt><dd><p>

  1203. 

  1204. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1205.         Byte1('p')

  1206. </span></dt><dd><p>

  1207.                 Identifies the message as an initial SASL response. Note that

  1208.                 this is also used for GSSAPI, SSPI and password response messages.

  1209.                 The exact message type is deduced from the context.

  1210. </p></dd><dt><span class="term">

  1211.         Int32

  1212. </span></dt><dd><p>

  1213.                 Length of message contents in bytes, including self.

  1214. </p></dd><dt><span class="term">

  1215.         String

  1216. </span></dt><dd><p>

  1217.                 Name of the SASL authentication mechanism that the client

  1218.                 selected.

  1219. </p></dd><dt><span class="term">

  1220.         Int32

  1221. </span></dt><dd><p>

  1222.                 Length of SASL mechanism specific "Initial Client Response" that

  1223.                 follows, or -1 if there is no Initial Response.

  1224. </p></dd><dt><span class="term">

  1225.         Byte<em class="replaceable"><code>n</code></em>

  1226. </span></dt><dd><p>

  1227.                 SASL mechanism specific "Initial Response".

  1228. </p></dd></dl></div><p>

  1229. </p></dd><dt><span class="term">

  1230. SASLResponse (F)

  1231. </span></dt><dd><p>

  1232. 

  1233. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1234.         Byte1('p')

  1235. </span></dt><dd><p>

  1236.                 Identifies the message as a SASL response. Note that

  1237.                 this is also used for GSSAPI, SSPI and password response messages.

  1238.                 The exact message type can be deduced from the context.

  1239. </p></dd><dt><span class="term">

  1240.         Int32

  1241. </span></dt><dd><p>

  1242.                 Length of message contents in bytes, including self.

  1243. </p></dd><dt><span class="term">

  1244.         Byte<em class="replaceable"><code>n</code></em>

  1245. </span></dt><dd><p>

  1246.                 SASL mechanism specific message data.

  1247. </p></dd></dl></div><p>

  1248. </p></dd><dt><span class="term">

  1249. SSLRequest (F)

  1250. </span></dt><dd><p>

  1251. 

  1252. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1253.         Int32(8)

  1254. </span></dt><dd><p>

  1255.                 Length of message contents in bytes, including self.

  1256. </p></dd><dt><span class="term">

  1257.         Int32(80877103)

  1258. </span></dt><dd><p>

  1259.                 The <acronym class="acronym">SSL</acronym> request code.  The value is chosen to contain

  1260.                 <code class="literal">1234</code> in the most significant 16 bits, and <code class="literal">5679</code> in the

  1261.                 least significant 16 bits.  (To avoid confusion, this code

  1262.                 must not be the same as any protocol version number.)

  1263. </p></dd></dl></div><p>

  1264. 

  1265. </p></dd><dt><span class="term">

  1266. GSSENCRequest (F)

  1267. </span></dt><dd><p>

  1268. 

  1269. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1270.         Int32(8)

  1271. </span></dt><dd><p>

  1272.                 Length of message contents in bytes, including self.

  1273. </p></dd><dt><span class="term">

  1274.         Int32(80877104)

  1275. </span></dt><dd><p>

  1276.                 The <acronym class="acronym">GSSAPI</acronym> Encryption request code.  The value is chosen to contain

  1277.                 <code class="literal">1234</code> in the most significant 16 bits, and <code class="literal">5680</code> in the

  1278.                 least significant 16 bits.  (To avoid confusion, this code

  1279.                 must not be the same as any protocol version number.)

  1280. </p></dd></dl></div><p>

  1281. 

  1282. </p></dd><dt><span class="term">

  1283. StartupMessage (F)

  1284. </span></dt><dd><p>

  1285. 

  1286. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1287.         Int32

  1288. </span></dt><dd><p>

  1289.                 Length of message contents in bytes, including self.

  1290. </p></dd><dt><span class="term">

  1291.         Int32(196608)

  1292. </span></dt><dd><p>

  1293.                 The protocol version number.  The most significant 16 bits are

  1294.                 the major version number (3 for the protocol described here).

  1295.                 The least significant 16 bits are the minor version number

  1296.                 (0 for the protocol described here).

  1297. </p></dd></dl></div><p>

  1298.         The protocol version number is followed by one or more pairs of

  1299.         parameter name and value strings.  A zero byte is required as a

  1300.         terminator after the last name/value pair.

  1301.         Parameters can appear in any

  1302.         order.  <code class="literal">user</code> is required, others are optional.

  1303.         Each parameter is specified as:

  1304. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1305.         String

  1306. </span></dt><dd><p>

  1307.                 The parameter name.  Currently recognized names are:

  1308. 

  1309. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1310.                 <code class="literal">user</code>

  1311. </span></dt><dd><p>

  1312.                         The database user name to connect as.  Required;

  1313.                         there is no default.

  1314. </p></dd><dt><span class="term">

  1315.                 <code class="literal">database</code>

  1316. </span></dt><dd><p>

  1317.                         The database to connect to.  Defaults to the user name.

  1318. </p></dd><dt><span class="term">

  1319.                 <code class="literal">options</code>

  1320. </span></dt><dd><p>

  1321.                         Command-line arguments for the backend.  (This is

  1322.                         deprecated in favor of setting individual run-time

  1323.                         parameters.)  Spaces within this string are

  1324.                         considered to separate arguments, unless escaped with

  1325.                         a backslash (<code class="literal">\</code>); write <code class="literal">\\</code> to

  1326.                         represent a literal backslash.

  1327. </p></dd><dt><span class="term">

  1328.                 <code class="literal">replication</code>

  1329. </span></dt><dd><p>

  1330.                         Used to connect in streaming replication mode, where

  1331.                         a small set of replication commands can be issued

  1332.                         instead of SQL statements. Value can be

  1333.                         <code class="literal">true</code>, <code class="literal">false</code>, or

  1334.                         <code class="literal">database</code>, and the default is

  1335.                         <code class="literal">false</code>. See

  1336.                         <a class="xref" href="protocol-replication.html" title="52.4. Streaming Replication Protocol">Section 52.4</a> for details.

  1337. </p></dd></dl></div><p>

  1338. 

  1339.                 In addition to the above, other parameters may be listed.

  1340.                 Parameter names beginning with <code class="literal">_pq_.</code> are

  1341.                 reserved for use as protocol extensions, while others are

  1342.                 treated as run-time parameters to be set at backend start

  1343.                 time.  Such settings will be applied during backend start

  1344.                 (after parsing the command-line arguments if any) and will

  1345.                 act as session defaults.

  1346. </p></dd><dt><span class="term">

  1347.         String

  1348. </span></dt><dd><p>

  1349.                 The parameter value.

  1350. </p></dd></dl></div><p>

  1351. 

  1352. </p></dd><dt><span class="term">

  1353. Sync (F)

  1354. </span></dt><dd><p>

  1355. 

  1356. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1357.         Byte1('S')

  1358. </span></dt><dd><p>

  1359.                 Identifies the message as a Sync command.

  1360. </p></dd><dt><span class="term">

  1361.         Int32(4)

  1362. </span></dt><dd><p>

  1363.                 Length of message contents in bytes, including self.

  1364. </p></dd></dl></div><p>

  1365. 

  1366. </p></dd><dt><span class="term">

  1367. Terminate (F)

  1368. </span></dt><dd><p>

  1369. 

  1370. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">

  1371.         Byte1('X')

  1372. </span></dt><dd><p>

  1373.                 Identifies the message as a termination.

  1374. </p></dd><dt><span class="term">

  1375.         Int32(4)

  1376. </span></dt><dd><p>

  1377.                 Length of message contents in bytes, including self.

  1378. </p></dd></dl></div><p>

  1379. 

  1380. </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-message-types.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-error-fields.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.6. Message Data Types </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 52.8. Error and Notice Message Fields</td></tr></table></div></body></html>
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