doc: Fix PQsslAttribute docs for compression

The compression parameter to PQsslAttribute has never returned the
compression method used, it has always returned "on" or "off since
it was added in commit 91fa7b4719ac. Backpatch through v10.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/B9EC60EC-F665-47E8-A221-398C76E382C9@yesql.se
Backpatch-through: v10

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 1f8e7875cfa9665038e86a387f356d1dd2208bfd..e4487cc32232d90a919ea3af783adefe3cdfe115 100644 (file)
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -2565,9 +2565,7 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
          <term><literal>compression</literal></term>
           <listitem>
            <para>
-            If SSL compression is in use, returns the name of the compression
-            algorithm, or "on" if compression is used but the algorithm is
-            not known. If compression is not in use, returns "off".
+            Returns "on" if SSL compression is in use, else it returns "off".
            </para>
           </listitem>
          </varlistentry>