doc: \123 and \x12 escapes in COPY are in database encoding.

hlinnaka · hlinnaka · commit e9a79c220bf5 · 2021-08-17T10:00:06.000+03:00
The backslash sequences, including \123 and \x12 escapes, are interpreted after encoding conversion. The docs failed to mention that. Backpatch to all supported versions. Reported-by: Andreas Grob Discussion: https://www.postgresql.org/message-id/17142-9181542ca1df75ab%40postgresql.org
diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
@@ -636,12 +636,12 @@ COPY <replaceable class="parameter">count</replaceable>
       <row>
        <entry><literal>\</literal><replaceable>digits</replaceable></entry>
        <entry>Backslash followed by one to three octal digits specifies
-       the character with that numeric code</entry>
+       the byte with that numeric code</entry>
       </row>
       <row>
        <entry><literal>\x</literal><replaceable>digits</replaceable></entry>
        <entry>Backslash <literal>x</literal> followed by one or two hex digits specifies
-       the character with that numeric code</entry>
+       the byte with that numeric code</entry>
       </row>
      </tbody>
     </tgroup>
@@ -673,6 +673,12 @@ COPY <replaceable class="parameter">count</replaceable>
     or vice versa).
    </para>
 
+   <para>
+     All backslash sequences are interpreted after encoding conversion.
+     The bytes specified with the octal and hex-digit backslash sequences must
+     form valid characters in the database encoding.
+   </para>
+
    <para>
     <command>COPY TO</command> will terminate each row with a Unix-style
     newline (<quote><literal>\n</literal></quote>).  Servers running on Microsoft Windows instead
