protocol.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

</varlistentry>
<varlistentry>
<term>
        Byte4
</term>
<listitem>
<para>
                The salt to use when encrypting the password.
</para>
</listitem>
</varlistentry>
</variablelist>

</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
AuthenticationSCMCredential (B)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Byte1('R')
</term>
<listitem>
<para>
                Identifies the message as an authentication request.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32(8)
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32(6)
</term>
<listitem>
<para>
                Specifies that an SCM credentials message is required.
</para>
</listitem>
</varlistentry>
</variablelist>

</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
BackendKeyData (B)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Byte1('K')
</term>
<listitem>
<para>
                Identifies the message as cancellation key data.
                The frontend must save these values if it wishes to be
                able to issue CancelRequest messages later.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32(12)
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                The process ID of this backend.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                The secret key of this backend.
</para>
</listitem>
</varlistentry>
</variablelist>

</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
Bind (F)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Byte1('B')
</term>
<listitem>
<para>
                Identifies the message as a Bind command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        String
</term>
<listitem>
<para>
                The name of the destination portal
                (an empty string selects the unnamed portal).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        String
</term>
<listitem>
<para>
                The name of the source prepared statement
                (an empty string selects the unnamed prepared statement).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int16
</term>
<listitem>
<para>
                The number of parameter format codes that follow
                (denoted <replaceable>C</> below).
                This can be zero to indicate that there are no parameters
                or that the parameters all use the default format (text);
                or one, in which case the specified format code is applied
                to all parameters; or it can equal the actual number of
                parameters.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int16[<replaceable>C</>]
</term>
<listitem>
<para>
                The parameter format codes.  Each must presently be
                zero (text) or one (binary).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int16
</term>
<listitem>
<para>
                The number of parameter values that follow (possibly zero).
                This must match the number of parameters needed by the query.
</para>
</listitem>
</varlistentry>
</variablelist>
        Next, the following pair of fields appear for each parameter:
<variablelist>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                The length of the parameter value, in bytes (this count
                does not include itself).  Can be zero.
                As a special case, -1 indicates a NULL parameter value.
                No value bytes follow in the NULL case.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Byte<replaceable>n</replaceable>
</term>
<listitem>
<para>
                The value of the parameter, in the format indicated by the
                associated format code.
                <replaceable>n</replaceable> is the above length.
</para>
</listitem>
</varlistentry>
</variablelist>
        After the last parameter, the following fields appear:
<variablelist>
<varlistentry>
<term>
        Int16
</term>
<listitem>
<para>
                The number of result-column format codes that follow
                (denoted <replaceable>R</> below).
                This can be zero to indicate that there are no result columns
                or that the result columns should all use the default format
                (text); 
                or one, in which case the specified format code is applied
                to all result columns (if any); or it can equal the actual
                number of result columns of the query.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int16[<replaceable>R</>]
</term>
<listitem>
<para>
                The result-column format codes.  Each must presently be
                zero (text) or one (binary).
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
BindComplete (B)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Byte1('2')
</term>
<listitem>
<para>
                Identifies the message as a Bind-complete indicator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32(4)
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varlistentry>
</variablelist>

</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
CancelRequest (F)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Int32(16)
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32(80877102)
</term>
<listitem>
<para>
                The cancel request code.  The value is chosen to contain
                <literal>1234</> in the most significant 16 bits, and <literal>5678</> in the
                least 16 significant bits.  (To avoid confusion, this code
                must not be the same as any protocol version number.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                The process ID of the target backend.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                The secret key for the target backend.
</para>
</listitem>
</varlistentry>
</variablelist>

</para>
</listitem>
</varlistentry>


<varlistentry>
<term>
Close (F)
</term>
<listitem>
<para>

<variablelist>
<varlistentry>
<term>
        Byte1('C')
</term>
<listitem>
<para>
                Identifies the message as a Close command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
        Int32
</term>
<listitem>
<para>
                Length of message contents in bytes, including self.
</para>
</listitem>
</varli