<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Message Data Types</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 8.0.11 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Frontend/Backend Protocol"
HREF="protocol.html"><LINK
REL="PREVIOUS"
TITLE="Message Flow"
HREF="protocol-flow.html"><LINK
REL="NEXT"
TITLE="Message Formats"
HREF="protocol-message-formats.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2007-02-02T03:57:22"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
>PostgreSQL 8.0.11 Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="protocol-flow.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="protocol.html"
>Fast Backward</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 42. Frontend/Backend Protocol</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="protocol.html"
>Fast Forward</A
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="protocol-message-formats.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PROTOCOL-MESSAGE-TYPES"
>42.3. Message Data Types</A
></H1
><P
>This section describes the base data types used in messages.
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Int<TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
>(<TT
CLASS="REPLACEABLE"
><I
>i</I
></TT
>)</DT
><DD
><P
> An <TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
>-bit integer in network byte
order (most significant byte first).
If <TT
CLASS="REPLACEABLE"
><I
>i</I
></TT
> is specified it
is the exact value that will appear, otherwise the value
is variable. Eg. Int16, Int32(42).</P
></DD
><DT
>Int<TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
>[<TT
CLASS="REPLACEABLE"
><I
>k</I
></TT
>]</DT
><DD
><P
> An array of <TT
CLASS="REPLACEABLE"
><I
>k</I
></TT
>
<TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
>-bit integers, each in network
byte order. The array length <TT
CLASS="REPLACEABLE"
><I
>k</I
></TT
>
is always determined by an earlier field in the message.
Eg. Int16[M].</P
></DD
><DT
>String(<TT
CLASS="REPLACEABLE"
><I
>s</I
></TT
>)</DT
><DD
><P
> A null-terminated string (C-style string). There is no
specific length limitation on strings.
If <TT
CLASS="REPLACEABLE"
><I
>s</I
></TT
> is specified it is the exact
value that will appear, otherwise the value is variable.
Eg. String, String("user").</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
><SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>There is no predefined limit</I
></SPAN
> on the length of a string
that can be returned by the backend. Good coding strategy for a frontend
is to use an expandable buffer so that anything that fits in memory can be
accepted. If that's not feasible, read the full string and discard trailing
characters that don't fit into your fixed-size buffer.</P
></BLOCKQUOTE
></DIV
></DD
><DT
>Byte<TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
>(<TT
CLASS="REPLACEABLE"
><I
>c</I
></TT
>)</DT
><DD
><P
> Exactly <TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
> bytes. If the field
width <TT
CLASS="REPLACEABLE"
><I
>n</I
></TT
> is not a constant, it is
always determinable from an earlier field in the message.
If <TT
CLASS="REPLACEABLE"
><I
>c</I
></TT
> is specified it is the exact
value. Eg. Byte2, Byte1('\n').</P
></DD
></DL
></DIV
><P></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="protocol-flow.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="protocol-message-formats.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Message Flow</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="protocol.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Message Formats</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
