Disallow dollar sign in operator names, instead allow it as a non-first

character in identifiers.  The first change eliminates the current need
to put spaces around parameter references, as in "x<=$2".  The second
change improves compatibility with Oracle and some other RDBMSes.  This
was discussed and agreed to back in January, but did not get done.

doc/src/sgml/release.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.193 2003/06/17 23:12:36 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.194 2003/06/19 23:22:40 tgl Exp $
 -->
 
 <appendix id="release">
@@ -24,6 +24,8 @@ CDATA means the content is "SGML-free", so you can write without
 worries about funny characters.
 -->
 <literallayout><![CDATA[
+Dollar sign ($) is no longer allowed in operator names
+Dollar sign ($) can be a non-first character in identifiers
 Precision in FLOAT(p) is now interpreted as bits, not decimal digits
 Functional indexes have been generalized into expressional indexes
 CHAR(n) to TEXT conversion automatically strips trailing blanks

doc/src/sgml/syntax.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.78 2003/06/06 15:04:01 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.79 2003/06/19 23:22:40 tgl Exp $
 -->
 
 <chapter id="sql-syntax">
@@ -109,10 +109,15 @@ INSERT INTO MY_TABLE VALUES (3, 'hi there');
     (<literal>a</literal>-<literal>z</literal>, but also letters with
     diacritical marks and non-Latin letters) or an underscore
     (<literal>_</literal>).  Subsequent characters in an identifier or
-    key word can be letters, digits
-    (<literal>0</literal>-<literal>9</literal>), or underscores,
-    although the SQL standard will not define a key word that contains
-    digits or starts or ends with an underscore.
+    key word can be letters, underscores, digits
+    (<literal>0</literal>-<literal>9</literal>), or dollar signs
+    (<literal>$</>).  Note that dollar signs are not allowed in identifiers
+    according to the letter of the SQL standard, so their use may render
+    applications less portable.
+    The SQL standard will not define a key word that contains
+    digits or starts or ends with an underscore, so identifiers of this
+    form are safe against possible conflict with future extensions of the
+    standard.
    </para>
 
    <para>
@@ -478,18 +483,11 @@ CAST ( '<replaceable>string</replaceable>' AS <replaceable>type</replaceable> )
     An operator is a sequence of up to <symbol>NAMEDATALEN</symbol>-1
     (63 by default) characters from the following list:
 <literallayout>
-+ - * / &lt; &gt; = ~ ! @ # % ^ &amp; | ` ? $
++ - * / &lt; &gt; = ~ ! @ # % ^ &amp; | ` ?
 </literallayout>
 
     There are a few restrictions on operator names, however:
     <itemizedlist>
-     <listitem>
-      <para>
-       <literal>$</> (dollar) cannot be a single-character operator, although it
-       can be part of a multiple-character operator name.
-      </para>
-     </listitem>
-
      <listitem>
       <para>
        <literal>--</literal> and <literal>/*</literal> cannot appear
@@ -503,7 +501,7 @@ CAST ( '<replaceable>string</replaceable>' AS <replaceable>type</replaceable> )
        A multiple-character operator name cannot end in <literal>+</> or <literal>-</>,
        unless the name also contains at least one of these characters:
 <literallayout>
-~ ! @ # % ^ &amp; | ` ? $
+~ ! @ # % ^ &amp; | ` ?
 </literallayout>
        For example, <literal>@-</literal> is an allowed operator name,
        but <literal>*-</literal> is not.  This restriction allows
@@ -539,9 +537,9 @@ CAST ( '<replaceable>string</replaceable>' AS <replaceable>type</replaceable> )
     <listitem>
      <para>
       A dollar sign (<literal>$</literal>) followed by digits is used
-      to represent the positional parameters in the body of a function
+      to represent a positional parameter in the body of a function
       definition or a prepared statement.  In other contexts the
-      dollar sign may be part of an operator name.
+      dollar sign may be part of an identifier.
      </para>
     </listitem>
 
@@ -965,9 +963,12 @@ SELECT 3 OPERATOR(pg_catalog.+) 4;
    <title>Positional Parameters</title>
 
    <para>
-    A positional parameter reference is used to indicate a parameter
+    A positional parameter reference is used to indicate a value
     that is supplied externally to an SQL statement.  Parameters are
-    used in SQL function definitions and in prepared queries.
+    used in SQL function definitions and in prepared queries.  Some
+    client libraries also support specifying data values separately
+    from the SQL command string, in which case parameters are used to
+    refer to the out-of-line data values.
     The form of a parameter reference is:
 <synopsis>
 $<replaceable>number</replaceable>