postgres.git / summary / log / commit / refs

commit    090a3870aa4ed334a06a5cd81b74fde368ecf379
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Fri Dec 23 17:53:09 2016 +0000

    Doc: improve index entry for "median".
    
    We had an index entry for "median" attached to the percentile_cont function
    entry, which was pretty useless because a person following the link would
    never realize that that function was the one they were being hinted to use.
    
    Instead, make the index entry point at the example in syntax-aggregates,
    and add a <seealso> link to "percentile".
    
    Also, since that example explicitly claims to be calculating the median,
    make it use percentile_cont not percentile_disc.  This makes no difference
    in terms of the larger goals of that section, but so far as I can find,
    nearly everyone thinks that "median" means the continuous not discrete
    calculation.
    
    Per gripe from Steven Winfield.  Back-patch to 9.4 where we introduced
    percentile_cont.
    
    Discussion: https://postgr.es/m/20161223102056.25614.1166@wrigleys.postgresql.org


 doc/src/sgml/func.sgml   |  3 ---
 doc/src/sgml/syntax.sgml | 14 ++++++++++++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 01e9489ddcf..5a3e9977e1a 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -12888,9 +12888,6 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
         <primary>percentile</primary>
         <secondary>continuous</secondary>
        </indexterm>
-       <indexterm>
-        <primary>median</primary>
-       </indexterm>
        <function>percentile_cont(<replaceable class="parameter">fraction</replaceable>) WITHIN GROUP (ORDER BY <replaceable class="parameter">sort_expression</replaceable>)</function>
       </entry>
       <entry>
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 63d39adc9ec..41d94f0ec54 100644
--- a/doc/src/sgml/syntax.sgml
+++ b/doc/src/sgml/syntax.sgml
@@ -1704,11 +1704,21 @@ SELECT string_agg(a ORDER BY a, ',') FROM table;  -- incorrect
     case, write just <literal>()</> not <literal>(*)</>.
     (<productname>PostgreSQL</> will actually accept either spelling, but
     only the first way conforms to the SQL standard.)
+   </para>
+
+   <para>
+    <indexterm>
+     <primary>median</primary>
+    </indexterm>
+    <indexterm>
+     <primary>median</primary>
+     <seealso>percentile</seealso>
+    </indexterm>
     An example of an ordered-set aggregate call is:
 
 <programlisting>
-SELECT percentile_disc(0.5) WITHIN GROUP (ORDER BY income) FROM households;
- percentile_disc
+SELECT percentile_cont(0.5) WITHIN GROUP (ORDER BY income) FROM households;
+ percentile_cont
 -----------------
            50489
 </programlisting>


[parent: ac1ec9c1f036]