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  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[email protected]

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 4f832a76aada693e3d9f253a154067f02ea088a9..571ad7c5939fec0352f8fdfdb1ed767d911593df 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -13700,9 +13700,6 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
         percentile
         continuous
        
-       
-        median
-       
        percentile_cont(fraction) WITHIN GROUP (ORDER BY sort_expression)
       
       

diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 000da39250fe29c5199897bb065ede7541b48ebf..4ea667bd52feca1e73b1a031980e4faee49f9e66 100644 (file)
--- a/doc/src/sgml/syntax.sgml
+++ b/doc/src/sgml/syntax.sgml
@@ -1694,11 +1694,21 @@ SELECT string_agg(a ORDER BY a, ',') FROM table;  -- incorrect
     case, write just () not (*).
     (PostgreSQL will actually accept either spelling, but
     only the first way conforms to the SQL standard.)
+   
+
+   
+    
+     median
+    
+    
+     median
+     percentile
+    
     An example of an ordered-set aggregate call is:
 
 
-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