0001-lead_lag_compatible_default-2.patch

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 461b748d89..14cb8e2ce6 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -19621,17 +19621,17 @@ SELECT count(*) FROM sometable;
         <indexterm>
          <primary>lag</primary>
         </indexterm>
-        <function>lag</function> ( <parameter>value</parameter> <type>anyelement</type>
+        <function>lag</function> ( <parameter>value</parameter> <type>anycompatible</type>
           <optional>, <parameter>offset</parameter> <type>integer</type>
-          <optional>, <parameter>default</parameter> <type>anyelement</type> </optional></optional> )
-        <returnvalue>anyelement</returnvalue>
+          <optional>, <parameter>default</parameter> <type>anycompatible</type> </optional></optional> )
+        <returnvalue>anycompatible</returnvalue>
        </para>
        <para>
         Returns <parameter>value</parameter> evaluated at
         the row that is <parameter>offset</parameter>
         rows before the current row within the partition; if there is no such
         row, instead returns <parameter>default</parameter>
-        (which must be of the same type as
+        (which must be of a type compatible with
         <parameter>value</parameter>).
         Both <parameter>offset</parameter> and
         <parameter>default</parameter> are evaluated
@@ -19646,17 +19646,17 @@ SELECT count(*) FROM sometable;
         <indexterm>
          <primary>lead</primary>
         </indexterm>
-        <function>lead</function> ( <parameter>value</parameter> <type>anyelement</type>
+        <function>lead</function> ( <parameter>value</parameter> <type>anycompatible</type>
           <optional>, <parameter>offset</parameter> <type>integer</type>
-          <optional>, <parameter>default</parameter> <type>anyelement</type> </optional></optional> )
-        <returnvalue>anyelement</returnvalue>
+          <optional>, <parameter>default</parameter> <type>anycompatible</type> </optional></optional> )
+        <returnvalue>anycompatible</returnvalue>
        </para>
        <para>
         Returns <parameter>value</parameter> evaluated at
         the row that is <parameter>offset</parameter>
         rows after the current row within the partition; if there is no such
         row, instead returns <parameter>default</parameter>
-        (which must be of the same type as
+        (which must be of a type compatible with
         <parameter>value</parameter>).
         Both <parameter>offset</parameter> and
         <parameter>default</parameter> are evaluated
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index f48f5fb4d9..6e7832b0f4 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -9729,8 +9729,8 @@
   proname => 'lag', prokind => 'w', prorettype => 'anyelement',
   proargtypes => 'anyelement int4', prosrc => 'window_lag_with_offset' },
 { oid => '3108', descr => 'fetch the Nth preceding row value with default',
-  proname => 'lag', prokind => 'w', prorettype => 'anyelement',
-  proargtypes => 'anyelement int4 anyelement',
+  proname => 'lag', prokind => 'w', prorettype => 'anycompatible',
+  proargtypes => 'anycompatible int4 anycompatible',
   prosrc => 'window_lag_with_offset_and_default' },
 { oid => '3109', descr => 'fetch the following row value',
   proname => 'lead', prokind => 'w', prorettype => 'anyelement',
@@ -9739,8 +9739,8 @@
   proname => 'lead', prokind => 'w', prorettype => 'anyelement',
   proargtypes => 'anyelement int4', prosrc => 'window_lead_with_offset' },
 { oid => '3111', descr => 'fetch the Nth following row value with default',
-  proname => 'lead', prokind => 'w', prorettype => 'anyelement',
-  proargtypes => 'anyelement int4 anyelement',
+  proname => 'lead', prokind => 'w', prorettype => 'anycompatible',
+  proargtypes => 'anycompatible int4 anycompatible',
   prosrc => 'window_lead_with_offset_and_default' },
 { oid => '3112', descr => 'fetch the first row value',
   proname => 'first_value', prokind => 'w', prorettype => 'anyelement',
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index 21c6cac491..19e2ac518a 100644
--- a/src/test/regress/expected/window.out
+++ b/src/test/regress/expected/window.out
@@ -300,6 +300,21 @@ SELECT lag(ten, four, 0) OVER (PARTITION BY four ORDER BY ten), ten, four FROM t
    0 |   3 |    3
 (10 rows)
 
+SELECT lag(ten, four, 0.7) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten;
+ lag | ten | four 
+-----+-----+------
+   0 |   0 |    0
+   0 |   0 |    0
+   4 |   4 |    0
+ 0.7 |   1 |    1
+   1 |   1 |    1
+   1 |   7 |    1
+   7 |   9 |    1
+ 0.7 |   0 |    2
+ 0.7 |   1 |    3
+ 0.7 |   3 |    3
+(10 rows)
+
 SELECT lead(ten) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
  lead | ten | four 
 ------+-----+------
@@ -345,6 +360,21 @@ SELECT lead(ten * 2, 1, -1) OVER (PARTITION BY four ORDER BY ten), ten, four FRO
    -1 |   3 |    3
 (10 rows)
 
+SELECT lead(ten * 2, 1, -1.4) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten;
+ lead | ten | four 
+------+-----+------
+    0 |   0 |    0
+    8 |   0 |    0
+ -1.4 |   4 |    0
+    2 |   1 |    1
+   14 |   1 |    1
+   18 |   7 |    1
+ -1.4 |   9 |    1
+ -1.4 |   0 |    2
+    6 |   1 |    3
+ -1.4 |   3 |    3
+(10 rows)
+
 SELECT first_value(ten) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
  first_value | ten | four 
 -------------+-----+------
diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql
index 9485aebce8..eae5fa6017 100644
--- a/src/test/regress/sql/window.sql
+++ b/src/test/regress/sql/window.sql
@@ -63,12 +63,14 @@ SELECT lag(ten) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHER
 SELECT lag(ten, four) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
 
 SELECT lag(ten, four, 0) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
+SELECT lag(ten, four, 0.7) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten;
 
 SELECT lead(ten) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
 
 SELECT lead(ten * 2, 1) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
 
 SELECT lead(ten * 2, 1, -1) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;
+SELECT lead(ten * 2, 1, -1.4) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten;
 
 SELECT first_value(ten) OVER (PARTITION BY four ORDER BY ten), ten, four FROM tenk1 WHERE unique2 < 10;