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<chapter id="protocol">

<title>Frontend/Backend Protocol</title>

(but note that these exist only within a session, and are never shared

across sessions). Existing prepared statements and portals are

referenced by names assigned when they were created. In addition,

an <quote>unnamed</> prepared statement and portal exist, for use with

queries that are to be executed and forgotten. This is slightly

more efficient than using named objects, since the backend knows that

it need not save the object's state for re-use.

an <quote>unnamed</> prepared statement and portal exist. Although these

behave largely the same as named objects, operations on them are optimized

for the case of executing a query only once and then discarding it,

whereas operations on named objects are optimized on the expectation

of multiple uses.

</para>

</sect2>

</sect1>

zero or more CopyData messages (always one per row), followed by CopyDone.

The backend then reverts to the command-processing mode it was

in before the <command>COPY</> started, and sends CommandComplete.

The frontend cannot abort the transfer (short of closing the connection),

The frontend cannot abort the transfer (except by closing the connection

or issuing a Cancel request),

but it can discard unwanted CopyData and CopyDone messages.

</para>

<literal>INSERT <replaceable>oid</replaceable>

<replaceable>rows</replaceable></literal>, where

<replaceable>rows</replaceable> is the number of rows

inserted, and <replaceable>oid</replaceable> is the object ID

of the inserted row if <Replaceable>rows</Replaceable> is 1,

otherwise <Replaceable>oid</Replaceable> is 0.

inserted. <replaceable>oid</replaceable> is the object ID

of the inserted row if <Replaceable>rows</Replaceable> is 1

and the target table has OIDs;

otherwise <Replaceable>oid</Replaceable> is 0.

</Para>

<Para>