Add null test to partition constraint for default range partitions.

Non-default range partitions have a constraint which include null
tests, and both default and non-default list partitions also have a
constraint which includes null tests, but for some reason this was
missed for default range partitions.  This could cause the partition
constraint to evaluate to false for rows that were (correctly) routed
to that partition by insert tuple routing, which could in turn
cause constraint exclusion to prune the default partition in cases
where it should not.

Amit Langote, reviewed by Kyotaro Horiguchi

Discussion: http://postgr.es/m/ba7aaeb1-4399-220e-70b4-62eade1522d0@lab.ntt.co.jp

Author: robertmhaas

src/backend/catalog/partition.c

@@ -2134,12 +2134,29 @@ get_qual_for_range(Relation parent, PartitionBoundSpec *spec,
 
 		if (or_expr_args != NIL)
 		{
-			/* OR all the non-default partition constraints; then negate it */
-			result = lappend(result,
-							 list_length(or_expr_args) > 1
-							 ? makeBoolExpr(OR_EXPR, or_expr_args, -1)
-							 : linitial(or_expr_args));
-			result = list_make1(makeBoolExpr(NOT_EXPR, result, -1));
+			Expr   *other_parts_constr;
+
+			/*
+			 * Combine the constraints obtained for non-default partitions
+			 * using OR.  As requested, each of the OR's args doesn't include
+			 * the NOT NULL test for partition keys (which is to avoid its
+			 * useless repetition).  Add the same now.
+			 */
+			other_parts_constr =
+						makeBoolExpr(AND_EXPR,
+							lappend(get_range_nulltest(key),
+									list_length(or_expr_args) > 1
+										? makeBoolExpr(OR_EXPR, or_expr_args,
+													   -1)
+										: linitial(or_expr_args)),
+									-1);
+
+			/*
+			 * Finally, the default partition contains everything *NOT*
+			 * contained in the non-default partitions.
+			 */
+			result = list_make1(makeBoolExpr(NOT_EXPR,
+										list_make1(other_parts_constr), -1));
 		}
 
 		return result;

src/test/regress/expected/inherit.out

@@ -1853,41 +1853,48 @@ drop table range_list_parted;
 -- check that constraint exclusion is able to cope with the partition
 -- constraint emitted for multi-column range partitioned tables
 create table mcrparted (a int, b int, c int) partition by range (a, abs(b), c);
+create table mcrparted_def partition of mcrparted default;
 create table mcrparted0 partition of mcrparted for values from (minvalue, minvalue, minvalue) to (1, 1, 1);
 create table mcrparted1 partition of mcrparted for values from (1, 1, 1) to (10, 5, 10);
 create table mcrparted2 partition of mcrparted for values from (10, 5, 10) to (10, 10, 10);
 create table mcrparted3 partition of mcrparted for values from (11, 1, 1) to (20, 10, 10);
 create table mcrparted4 partition of mcrparted for values from (20, 10, 10) to (20, 20, 20);
 create table mcrparted5 partition of mcrparted for values from (20, 20, 20) to (maxvalue, maxvalue, maxvalue);
-explain (costs off) select * from mcrparted where a = 0;	-- scans mcrparted0
-          QUERY PLAN          
-------------------------------
+explain (costs off) select * from mcrparted where a = 0;	-- scans mcrparted0, mcrparted_def
+           QUERY PLAN            
+---------------------------------
  Append
    ->  Seq Scan on mcrparted0
          Filter: (a = 0)
-(3 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: (a = 0)
+(5 rows)
 
-explain (costs off) select * from mcrparted where a = 10 and abs(b) < 5;	-- scans mcrparted1
+explain (costs off) select * from mcrparted where a = 10 and abs(b) < 5;	-- scans mcrparted1, mcrparted_def
                  QUERY PLAN                  
 ---------------------------------------------
  Append
    ->  Seq Scan on mcrparted1
          Filter: ((a = 10) AND (abs(b) < 5))
-(3 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: ((a = 10) AND (abs(b) < 5))
+(5 rows)
 
-explain (costs off) select * from mcrparted where a = 10 and abs(b) = 5;	-- scans mcrparted1, mcrparted2
+explain (costs off) select * from mcrparted where a = 10 and abs(b) = 5;	-- scans mcrparted1, mcrparted2, mcrparted_def
                  QUERY PLAN                  
 ---------------------------------------------
  Append
    ->  Seq Scan on mcrparted1
          Filter: ((a = 10) AND (abs(b) = 5))
    ->  Seq Scan on mcrparted2
          Filter: ((a = 10) AND (abs(b) = 5))
-(5 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: ((a = 10) AND (abs(b) = 5))
+(7 rows)
 
 explain (costs off) select * from mcrparted where abs(b) = 5;	-- scans all partitions
-          QUERY PLAN          
-------------------------------
+           QUERY PLAN            
+---------------------------------
  Append
    ->  Seq Scan on mcrparted0
          Filter: (abs(b) = 5)
@@ -1899,7 +1906,9 @@ explain (costs off) select * from mcrparted where abs(b) = 5;	-- scans all parti
          Filter: (abs(b) = 5)
    ->  Seq Scan on mcrparted5
          Filter: (abs(b) = 5)
-(11 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: (abs(b) = 5)
+(13 rows)
 
 explain (costs off) select * from mcrparted where a > -1;	-- scans all partitions
              QUERY PLAN              
@@ -1917,7 +1926,9 @@ explain (costs off) select * from mcrparted where a > -1;	-- scans all partition
          Filter: (a > '-1'::integer)
    ->  Seq Scan on mcrparted5
          Filter: (a > '-1'::integer)
-(13 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: (a > '-1'::integer)
+(15 rows)
 
 explain (costs off) select * from mcrparted where a = 20 and abs(b) = 10 and c > 10;	-- scans mcrparted4
                         QUERY PLAN                         
@@ -1927,7 +1938,7 @@ explain (costs off) select * from mcrparted where a = 20 and abs(b) = 10 and c >
          Filter: ((c > 10) AND (a = 20) AND (abs(b) = 10))
 (3 rows)
 
-explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mcrparted3, mcrparte4, mcrparte5
+explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mcrparted3, mcrparte4, mcrparte5, mcrparted_def
                QUERY PLAN                
 -----------------------------------------
  Append
@@ -1937,7 +1948,9 @@ explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mc
          Filter: ((c > 20) AND (a = 20))
    ->  Seq Scan on mcrparted5
          Filter: ((c > 20) AND (a = 20))
-(7 rows)
+   ->  Seq Scan on mcrparted_def
+         Filter: ((c > 20) AND (a = 20))
+(9 rows)
 
 drop table mcrparted;
 -- check that partitioned table Appends cope with being referenced in

src/test/regress/expected/update.out

@@ -227,7 +227,7 @@ create table part_def partition of range_parted default;
  a      | text    |           |          |         | extended |              | 
  b      | integer |           |          |         | plain    |              | 
 Partition of: range_parted DEFAULT
-Partition constraint: (NOT (((a = 'a'::text) AND (b >= 1) AND (b < 10)) OR ((a = 'a'::text) AND (b >= 10) AND (b < 20)) OR ((a = 'b'::text) AND (b >= 1) AND (b < 10)) OR ((a = 'b'::text) AND (b >= 10) AND (b < 20))))
+Partition constraint: (NOT ((a IS NOT NULL) AND (b IS NOT NULL) AND (((a = 'a'::text) AND (b >= 1) AND (b < 10)) OR ((a = 'a'::text) AND (b >= 10) AND (b < 20)) OR ((a = 'b'::text) AND (b >= 1) AND (b < 10)) OR ((a = 'b'::text) AND (b >= 10) AND (b < 20)))))
 
 insert into range_parted values ('c', 9);
 -- ok

src/test/regress/sql/inherit.sql

@@ -664,19 +664,20 @@ drop table range_list_parted;
 -- check that constraint exclusion is able to cope with the partition
 -- constraint emitted for multi-column range partitioned tables
 create table mcrparted (a int, b int, c int) partition by range (a, abs(b), c);
+create table mcrparted_def partition of mcrparted default;
 create table mcrparted0 partition of mcrparted for values from (minvalue, minvalue, minvalue) to (1, 1, 1);
 create table mcrparted1 partition of mcrparted for values from (1, 1, 1) to (10, 5, 10);
 create table mcrparted2 partition of mcrparted for values from (10, 5, 10) to (10, 10, 10);
 create table mcrparted3 partition of mcrparted for values from (11, 1, 1) to (20, 10, 10);
 create table mcrparted4 partition of mcrparted for values from (20, 10, 10) to (20, 20, 20);
 create table mcrparted5 partition of mcrparted for values from (20, 20, 20) to (maxvalue, maxvalue, maxvalue);
-explain (costs off) select * from mcrparted where a = 0;	-- scans mcrparted0
-explain (costs off) select * from mcrparted where a = 10 and abs(b) < 5;	-- scans mcrparted1
-explain (costs off) select * from mcrparted where a = 10 and abs(b) = 5;	-- scans mcrparted1, mcrparted2
+explain (costs off) select * from mcrparted where a = 0;	-- scans mcrparted0, mcrparted_def
+explain (costs off) select * from mcrparted where a = 10 and abs(b) < 5;	-- scans mcrparted1, mcrparted_def
+explain (costs off) select * from mcrparted where a = 10 and abs(b) = 5;	-- scans mcrparted1, mcrparted2, mcrparted_def
 explain (costs off) select * from mcrparted where abs(b) = 5;	-- scans all partitions
 explain (costs off) select * from mcrparted where a > -1;	-- scans all partitions
 explain (costs off) select * from mcrparted where a = 20 and abs(b) = 10 and c > 10;	-- scans mcrparted4
-explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mcrparted3, mcrparte4, mcrparte5
+explain (costs off) select * from mcrparted where a = 20 and c > 20; -- scans mcrparted3, mcrparte4, mcrparte5, mcrparted_def
 drop table mcrparted;
 
 -- check that partitioned table Appends cope with being referenced in