Doc: remove misleading info about ecpg's CONNECT/DISCONNECT DEFAULT.

tglsfdc · tglsfdc · commit 9e8a18d692a9 · 2023-10-25T17:34:47.000-04:00
As far as I can see, ecpg has no notion of a "default" open connection. You can do "CONNECT TO DEFAULT" but that just specifies letting libpq use all its default connection parameters --- the resulting connection is not special subsequently. In particular, SET CONNECTION = DEFAULT and DISCONNECT DEFAULT simply act on a connection named DEFAULT, if you've made one; they do not have special lookup rules. But the documentation of these commands makes it look like they do. Simplest fix, I think, is just to remove the paras suggesting that DEFAULT is special here. Also, SET CONNECTION *does* have one special lookup rule, which is that it recognizes CURRENT as an alias for the currently selected connection. SET CONNECTION = CURRENT is a no-op, so it's pretty useless, but nonetheless it does something different from selecting a connection by name; so we'd better document it. Per report from Sylvain Frandaz. Back-patch to all supported versions. Discussion: https://postgr.es/m/169824721149.1769274.1553568436817652238@wrigleys.postgresql.org
diff --git a/doc/src/sgml/ecpg.sgml b/doc/src/sgml/ecpg.sgml
@@ -343,12 +343,6 @@ EXEC SQL DISCONNECT <optional><replaceable>connection</replaceable></optional>;
      </simpara>
     </listitem>
 
-    <listitem>
-     <simpara>
-      <literal>DEFAULT</literal>
-     </simpara>
-    </listitem>
-
     <listitem>
      <simpara>
       <literal>CURRENT</literal>
@@ -6879,7 +6873,6 @@ EXEC SQL DEALLOCATE DESCRIPTOR mydesc;
 <synopsis>
 DISCONNECT <replaceable class="parameter">connection_name</replaceable>
 DISCONNECT [ CURRENT ]
-DISCONNECT DEFAULT
 DISCONNECT ALL
 </synopsis>
    </refsynopsisdiv>
@@ -6920,15 +6913,6 @@ DISCONNECT ALL
       </listitem>
      </varlistentry>
 
-     <varlistentry>
-      <term><literal>DEFAULT</literal></term>
-      <listitem>
-       <para>
-        Close the default connection.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry>
       <term><literal>ALL</literal></term>
       <listitem>
@@ -6947,13 +6931,11 @@ DISCONNECT ALL
 int
 main(void)
 {
-    EXEC SQL CONNECT TO testdb AS DEFAULT USER testuser;
     EXEC SQL CONNECT TO testdb AS con1 USER testuser;
     EXEC SQL CONNECT TO testdb AS con2 USER testuser;
     EXEC SQL CONNECT TO testdb AS con3 USER testuser;
 
     EXEC SQL DISCONNECT CURRENT;  /* close con3          */
-    EXEC SQL DISCONNECT DEFAULT;  /* close DEFAULT       */
     EXEC SQL DISCONNECT ALL;      /* close con2 and con1 */
 
     return 0;
@@ -7473,10 +7455,10 @@ SET CONNECTION [ TO | = ] <replaceable class="parameter">connection_name</replac
      </varlistentry>
 
      <varlistentry>
-      <term><literal>DEFAULT</literal></term>
+      <term><literal>CURRENT</literal></term>
       <listitem>
        <para>
-        Set the connection to the default connection.
+        Set the connection to the current connection (thus, nothing happens).
        </para>
       </listitem>
      </varlistentry>
