Implement the width_bucket() function, per SQL2003. This commit only adds

a variant of the function for the 'numeric' datatype; it would be possible
to add additional variants for other datatypes, but I haven't done so yet.

This commit includes regression tests and minimal documentation; if we
want developers to actually use this function in applications, we'll
probably need to document what it does more fully.

3 files changed, 25 insertions, 10 deletions

diff --git a/doc/src/sgml/errcodes.sgml b/doc/src/sgml/errcodes.sgml
index 2f211f462e8..295c41ffad8 100644
--- a/doc/src/sgml/errcodes.sgml
+++ b/doc/src/sgml/errcodes.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/errcodes.sgml,v 1.4 2004/05/14 18:04:02 neilc Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/errcodes.sgml,v 1.5 2004/05/14 21:42:27 neilc Exp $ -->
 
 <appendix id="errcodes-appendix">
  <title><productname>PostgreSQL</productname> Error Codes</title>
@@ -311,6 +311,11 @@
 </row>
 
 <row>
+<entry><literal>2201G</literal></entry>
+<entry>INVALID ARGUMENT FOR WIDTH BUCKET FUNCTION</entry>
+</row>
+
+<row>
 <entry><literal>22018</literal></entry>
 <entry>INVALID CHARACTER VALUE FOR CAST</entry>
 </row>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 1dde8b59a3c..6fd36fe77bc 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.201 2004/05/10 22:44:42 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.202 2004/05/14 21:42:27 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -751,6 +751,16 @@ PostgreSQL documentation
        <entry><literal>42.43</literal></entry>
       </row>
 
+      <row>
+       <entry><literal><function>width_bucket</function>(<parameter>op</parameter> <type>numeric</type>, <parameter>b1</parameter> <type>numeric</type>, <parameter>b2</parameter> <type>numeric</type>, <parameter>count</parameter> <type>integer</type>)</literal></entry>
+       <entry><type>integer</type></entry>
+       <entry>return the bucket to which <parameter>operand</> would
+       be assigned in an equidepth histogram with <parameter>count</>
+       buckets, an upper bound of <parameter>b1</>, and a lower bound
+       of <parameter>b2</></entry>
+       <entry><literal>width_bucket(5.35, 0.024, 10.06, 5)</literal></entry>
+       <entry><literal>3</literal></entry>
+      </row>
      </tbody>
     </tgroup>
    </table>
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index a3c24a1c4c1..ed2a502c69e 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.82 2004/05/10 22:44:43 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.83 2004/05/14 21:42:27 neilc Exp $
 -->
 
  <sect1 id="xfunc">
@@ -56,7 +56,7 @@ $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.82 2004/05/10 22:44:43 tgl Exp $
   </para>
 
   <para>
-   It's easiest to define <acronym>SQL</acronym> 
+   It's easiest to define <acronym>SQL</acronym>
    functions, so we'll start by discussing those.
    Most of the concepts presented for <acronym>SQL</acronym> functions
    will carry over to the other types of functions.
@@ -64,12 +64,12 @@ $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.82 2004/05/10 22:44:43 tgl Exp $
 
   <para>
    Throughout this chapter, it can be useful to look at the reference
-   page of the <command>CREATE FUNCTION</command> command to
-   understand the examples better.
-   Some examples from this chapter
-   can be found in <filename>funcs.sql</filename> 
-   and <filename>funcs.c</filename> in the <filename>src/tutorial</>
-   directory in the <productname>PostgreSQL</productname> source distribution.
+   page of the <xref linkend="sql-createfunction"> command to
+   understand the examples better.  Some examples from this chapter
+   can be found in <filename>funcs.sql</filename> and
+   <filename>funcs.c</filename> in the <filename>src/tutorial</>
+   directory in the <productname>PostgreSQL</productname> source
+   distribution.
   </para>
   </sect1>