<row>       <entry><literal>\f</></entry>       <entry>Form feed (ASCII 12)</entry>      </row>      <row>       <entry><literal>\n</></entry>       <entry>Newline (ASCII 10)</entry>      </row>      <row>       <entry><literal>\r</></entry>       <entry>Carriage return (ASCII 13)</entry>      </row>      <row>       <entry><literal>\t</></entry>       <entry>Tab (ASCII 9)</entry>      </row>      <row>       <entry><literal>\v</></entry>       <entry>Vertical tab (ASCII 11)</entry>      </row>      <row>       <entry><literal>\</><replaceable>digits</></entry>       <entry>Backslash followed by one to three octal digits specifies       the character with that numeric code</entry>      </row>     </tbody>    </tgroup>   </informaltable>    Presently, <command>COPY TO</command> will never emit an octal-digits    backslash sequence, but it does use the other sequences listed above    for those control characters.   </para>   <para>    Any other backslashed character that is not mentioned in the above table    will be taken to represent itself.  However, beware of adding backslashes    unnecessarily, since that might accidentally produce a string matching the    end-of-data marker (<literal>\.</>) or the null string (<literal>\N</> by    default).  These strings will be recognized before any other backslash    processing is done.   </para>   <para>    It is strongly recommended that applications generating COPY data convert    data newlines and carriage returns to the <literal>\n</> and    <literal>\r</> sequences respectively.  At present it is    possible to represent a data carriage return by a backslash and carriage    return, and to represent a data newline by a backslash and newline.      However, these representations might not be accepted in future releases.    They are also highly vulnerable to corruption if the COPY file is    transferred across different machines (for example, from Unix to Windows    or vice versa).   </para>   <para>    <command>COPY TO</command> will terminate each row with a Unix-style     newline (<quote><literal>\n</></>).  Servers running on MS Windows instead    output carriage return/newline (<quote><literal>\r\n</></>), but only for    <command>COPY</> to a server file; for consistency across platforms,    <command>COPY TO STDOUT</> always sends <quote><literal>\n</></>    regardless of server platform.    <command>COPY FROM</command> can handle lines ending with newlines,    carriage returns, or carriage return/newlines.  To reduce the risk of    error due to un-backslashed newlines or carriage returns that were    meant as data, <command>COPY FROM</command> will complain if the line    endings in the input are not all alike.   </para>  </refsect2>  <refsect2>   <title>Binary Format</title>   <para>    The file format used for <command>COPY BINARY</command> changed in    <productname>PostgreSQL</productname> 7.4. The new format consists    of a file header, zero or more tuples containing the row data, and    a file trailer. Headers and data are now in network byte order.   </para>   <refsect3>    <title>File Header</title>    <para>     The file header consists of 15 bytes of fixed fields, followed     by a variable-length header extension area.  The fixed fields are:    <variablelist>     <varlistentry>      <term>Signature</term>      <listitem>       <para>11-byte sequence <literal>PGCOPY\n\377\r\n\0</> --- note that the zero byteis a required part of the signature.  (The signature is designed to alloweasy identification of files that have been munged by a non-8-bit-cleantransfer.  This signature will be changed by end-of-line-translationfilters, dropped zero bytes, dropped high bits, or parity changes.)       </para>      </listitem>     </varlistentry>     <varlistentry>      <term>Flags field</term>      <listitem>       <para>32-bit integer bit mask to denote important aspects of the file format. Bitsare numbered from 0 (<acronym>LSB</>) to 31 (<acronym>MSB</>).  Note thatthis field is stored in network byte order (most significant byte first),as are all the integer fields used in the file format.  Bits16-31 are reserved to denote critical file format issues; a readershould abort if it finds an unexpected bit set in this range. Bits 0-15are reserved to signal backwards-compatible format issues; a readershould simply ignore any unexpected bits set in this range. Currentlyonly one flag bit is defined, and the rest must be zero:        <variablelist>         <varlistentry>          <term>Bit 16</term>          <listitem>           <para>            if 1, OIDs are included in the data; if 0, not           </para>          </listitem>         </varlistentry>        </variablelist>       </para>      </listitem>     </varlistentry>     <varlistentry>      <term>Header extension area length</term>      <listitem>       <para>32-bit integer, length in bytes of remainder of header, not including self.Currently, this is zero, and the first tuple followsimmediately.  Future changes to the format might allow additional datato be present in the header.  A reader should silently skip over any headerextension data it does not know what to do with.       </para>      </listitem>     </varlistentry>    </variablelist>    </para>    <para>The header extension area is envisioned to contain a sequence ofself-identifying chunks.  The flags field is not intended to tell readerswhat is in the extension area.  Specific design of header extension contentsis left for a later release.    </para>    <para>     This design allows for both backwards-compatible header additions (add     header extension chunks, or set low-order flag bits) and     non-backwards-compatible changes (set high-order flag bits to signal such     changes, and add supporting data to the extension area if needed).    </para>   </refsect3>   <refsect3>    <title>Tuples</title>    <para>Each tuple begins with a 16-bit integer count of the number of fields in thetuple.  (Presently, all tuples in a table will have the same count, but thatmight not always be true.)  Then, repeated for each field in the tuple, thereis a 32-bit length word followed by that many bytes of field data.  (Thelength word does not include itself, and can be zero.)  As a special case,-1 indicates a NULL field value.  No value bytes follow in the NULL case.    </para>    <para>There is no alignment padding or any other extra data between fields.    </para>    <para>Presently, all data values in a <command>COPY BINARY</command> file areassumed to be in binary format (format code one).  It is anticipated that afuture extension may add a header field that allows per-column format codesto be specified.    </para>    <para>To determine the appropriate binary format for the actual tuple data youshould consult the <productname>PostgreSQL</productname> source, inparticular the <function>*send</> and <function>*recv</> functions foreach column's data type (typically these functions are found in the<filename>src/backend/utils/adt/</filename> directory of the sourcedistribution).    </para>    <para>If OIDs are included in the file, the OID field immediately follows thefield-count word.  It is a normal field except that it's not includedin the field-count.  In particular it has a length word --- this will allowhandling of 4-byte vs. 8-byte OIDs without too much pain, and will allowOIDs to be shown as null if that ever proves desirable.    </para>   </refsect3>   <refsect3>    <title>File Trailer</title>    <para>     The file trailer consists of a 16-bit integer word containing -1.  This     is easily distinguished from a tuple's field-count word.    </para>    <para>     A reader should report an error if a field-count word is neither -1     nor the expected number of columns.  This provides an extra     check against somehow getting out of sync with the data.    </para>   </refsect3>  </refsect2> </refsect1>  <refsect1>  <title>Examples</title>  <para>   The following example copies a table to the client   using the vertical bar (<literal>|</literal>) as the field delimiter:<programlisting>COPY country TO STDOUT WITH DELIMITER '|';</programlisting>  </para>  <para>   To copy data from a file into the <literal>country</> table:<programlisting>COPY country FROM '/usr1/proj/bray/sql/country_data';</programlisting>  </para>  <para>   Here is a sample of data suitable for copying into a table from   <literal>STDIN</literal>:<programlisting>AF      AFGHANISTANAL      ALBANIADZ      ALGERIAZM      ZAMBIAZW      ZIMBABWE</programlisting>   Note that the white space on each line is actually a tab character.  </para>  <para>   The following is the same data, output in binary format.   The data is shown after filtering through the   Unix utility <command>od -c</command>. The table has three columns;   the first has type <type>char(2)</type>, the second has type <type>text</type>,   and the third has type <type>integer</type>. All the rows have a null value   in the third column.<programlisting>0000000   P   G   C   O   P   Y  \n 377  \r  \n  \0  \0  \0  \0  \0  \00000020  \0  \0  \0  \0 003  \0  \0  \0 002   A   F  \0  \0  \0 013   A0000040   F   G   H   A   N   I   S   T   A   N 377 377 377 377  \0 0030000060  \0  \0  \0 002   A   L  \0  \0  \0 007   A   L   B   A   N   I0000100   A 377 377 377 377  \0 003  \0  \0  \0 002   D   Z  \0  \0  \00000120 007   A   L   G   E   R   I   A 377 377 377 377  \0 003  \0  \00000140  \0 002   Z   M  \0  \0  \0 006   Z   A   M   B   I   A 377 3770000160 377 377  \0 003  \0  \0  \0 002   Z   W  \0  \0  \0  \b   Z   I0000200   M   B   A   B   W   E 377 377 377 377 377 377</programlisting>  </para> </refsect1>  <refsect1>  <title>Compatibility</title>    <para>   There is no <command>COPY</command> statement in the SQL standard.  </para>  <para>   The following syntax was used before PostgreSQL version 7.3 and is   still supported:<synopsis>COPY [ BINARY ] <replaceable class="parameter">tablename</replaceable> [ WITH OIDS ]    FROM { '<replaceable class="parameter">filename</replaceable>' | STDIN }    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter</replaceable>' ]    [ WITH NULL AS '<replaceable class="parameter">null string</replaceable>' ]COPY [ BINARY ] <replaceable class="parameter">tablename</replaceable> [ WITH OIDS ]    TO { '<replaceable class="parameter">filename</replaceable>' | STDOUT }    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter</replaceable>' ]    [ WITH NULL AS '<replaceable class="parameter">null string</replaceable>' ]</synopsis>  </para> </refsect1></refentry><!-- Keep this comment at the end of the fileLocal variables:mode: sgmlsgml-omittag:nilsgml-shorttag:tsgml-minimize-attributes:nilsgml-always-quote-attributes:tsgml-indent-step:1sgml-indent-data:tsgml-parent-document:nilsgml-default-dtd-file:"../reference.ced"sgml-exposed-tags:nilsgml-local-catalogs:"/usr/lib/sgml/catalog"sgml-local-ecat-files:nilEnd:-->