WL#2985 "Partition Pruning": post-review fixes:

- Added more comments.
- Added a RANGE_OPT_PARAM::remove_jump_scans flag that disables construction of index_merge
  SEL_TREEs that represent unusable conditions like "key1part1<c1 OR key2part2<c2"
- make prune_partitions() function handle the case where range analysis produces a list of 
  index_merge trees (it turned out that this is possible, appropriate test case added).
- Other small fixes.


mysql-test/r/partition_pruning.result:
  WL#2985 "Partition Pruning": post-review fixes: more test cases
mysql-test/t/partition_pruning.test:
  WL#2985 "Partition Pruning": post-review fixes: more test cases
sql/opt_range.cc:
  WL#2985 "Partition Pruning": post-review fixes:
  - Added more comments.
  - Fix the debug printouts
  - Added a RANGE_OPT_PARAM::remove_jump_scans flag that disables construction of index_merge
    SEL_TREEs that represent unusable conditions like "key1part1<c1 OR key2part2<c2"
  - make prune_partitions() function handle the case where range analysis produces a list of 
    index_merge trees (it turned out that this is possible, appropriate test case added).
sql/sql_partition.cc:
  WL#2985 "Partition Pruning": post-review fixes: make requested edits in comments.
sql/table.h:
  WL#2985 "Partition Pruning": post-review fixes: added bool TABLE::no_partitions_used
  (this change was missed when making the original cset)

mysql-test/r/partition_pruning.result

@@ -213,3 +213,48 @@ explain partitions select * from t1 where a='b';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	3	Using where
 drop table t1;
+create table t1 (
+a1 int not null
+)
+partition by range (a1) (
+partition p0 values less than (3),
+partition p1 values less than (6),
+partition p2 values less than (9)
+);
+insert into t1 values (1),(2),(3);
+explain partitions select * from t1 where a1 > 3;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	p1,p2	ALL	NULL	NULL	NULL	NULL	3	Using where
+explain partitions select * from t1 where a1 >= 3;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	p1,p2	ALL	NULL	NULL	NULL	NULL	3	Using where
+explain partitions select * from t1 where a1 < 3 and a1 > 3;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+drop table t1;
+create table t3 (a int, b int) 
+partition by list(a) subpartition by hash(b) subpartitions 4 (
+partition p0 values in (1),
+partition p1 values in (2),
+partition p2 values in (3),
+partition p3 values in (4)
+);
+insert into t3 values (1,1),(2,2),(3,3);
+explain partitions select * from t3 where a=2 or b=1;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t3	p0_sp1,p1_sp0,p1_sp1,p1_sp2,p1_sp3,p2_sp1,p3_sp1	ALL	NULL	NULL	NULL	NULL	3	Using where
+explain partitions select * from t3 where a=4 or b=2;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t3	p0_sp2,p1_sp2,p2_sp2,p3_sp0,p3_sp1,p3_sp2,p3_sp3	ALL	NULL	NULL	NULL	NULL	3	Using where
+explain partitions select * from t3 where (a=2 or b=1) and (a=4 or b=2) ;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t3	p1_sp2,p3_sp1	ALL	NULL	NULL	NULL	NULL	3	Using where
+create table t1 (a int) partition by hash(a) partitions 2;
+insert into t1 values (1),(2);
+explain partitions select * from t1 where a is null;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	2	Using where
+explain partitions select * from t1 where a is not null;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	2	Using where
+drop table t1;

mysql-test/t/partition_pruning.test

@@ -192,4 +192,46 @@ insert into t1 values ('a'),('b'),('c');
 explain partitions select * from t1 where a='b';
 drop table t1;
 
+#
+# Test cases for bugs found in code review:
+#
+create table t1 (
+  a1 int not null
+)
+partition by range (a1) (
+  partition p0 values less than (3),
+  partition p1 values less than (6),
+  partition p2 values less than (9)
+);
+insert into t1 values (1),(2),(3);
+explain partitions select * from t1 where a1 > 3;
+explain partitions select * from t1 where a1 >= 3;
+
+explain partitions select * from t1 where a1 < 3 and a1 > 3;
+drop table t1;
+
+#
+create table t3 (a int, b int) 
+  partition by list(a) subpartition by hash(b) subpartitions 4 (
+    partition p0 values in (1),
+    partition p1 values in (2),
+    partition p2 values in (3),
+    partition p3 values in (4)
+  );
+insert into t3 values (1,1),(2,2),(3,3);
+
+explain partitions select * from t3 where a=2 or b=1;
+explain partitions select * from t3 where a=4 or b=2;
+explain partitions select * from t3 where (a=2 or b=1) and (a=4 or b=2) ;
+
+# Test for NULLs
+create table t1 (a int) partition by hash(a) partitions 2;
+insert into t1 values (1),(2);
+explain partitions select * from t1 where a is null;
+
+# this selects both
+explain partitions select * from t1 where a is not null;
+drop table t1;
 
+# No tests for NULLs in RANGE(monotonic_expr()) - they depend on BUG#15447
+# being fixed.

sql/sql_partition.cc

@@ -2493,9 +2493,10 @@ notfound:
   DBUG_RETURN(TRUE);
 }
 
+
 /*
-  Find the part of part_info->list_array that corresponds to given interval
-  
+  Find the sub-array part_info->list_array that corresponds to given interval
+
   SYNOPSIS 
     get_list_array_idx_for_endpoint()
       part_info         Partitioning info (partitioning type must be LIST)
@@ -2504,17 +2505,16 @@ notfound:
       include_endpoint  TRUE iff the interval includes the endpoint
 
   DESCRIPTION
-    This function finds the part of part_info->list_array where values of
+    This function finds the sub-array of part_info->list_array where values of
     list_array[idx].list_value are contained within the specifed interval.
     list_array is ordered by list_value, so
     1. For [a; +inf) or (a; +inf)-type intervals (left_endpoint==TRUE), the 
-       sought array part starts at some index idx and continues till array 
-       end.
+       sought sub-array starts at some index idx and continues till array end.
        The function returns first number idx, such that 
        list_array[idx].list_value is contained within the passed interval.
        
     2. For (-inf; a] or (-inf; a)-type intervals (left_endpoint==FALSE), the
-       sought array part starts at array start and continues till some last 
+       sought sub-array starts at array start and continues till some last 
        index idx.
        The function returns first number idx, such that 
        list_array[idx].list_value is NOT contained within the passed interval.
@@ -2522,14 +2522,14 @@ notfound:
        returned.
 
   NOTE
-    The caller will call this function and then will run along the part of 
+    The caller will call this function and then will run along the sub-array of
     list_array to collect partition ids. If the number of list values is 
     significantly higher then number of partitions, this could be slow and
     we could invent some other approach. The "run over list array" part is
     already wrapped in a get_next()-like function.
 
   RETURN
-    The edge of corresponding part_info->list_array part.
+    The edge of corresponding sub-array of part_info->list_array
 */
 
 uint32 get_list_array_idx_for_endpoint(partition_info *part_info,
@@ -2541,6 +2541,7 @@ uint32 get_list_array_idx_for_endpoint(partition_info *part_info,
   uint list_index;
   longlong list_value;
   uint min_list_index= 0, max_list_index= part_info->no_list_values - 1;
+  /* Get the partitioning function value for the endpoint */
   longlong part_func_value= part_info->part_expr->val_int();
   while (max_list_index >= min_list_index)
   {
@@ -2596,8 +2597,8 @@ bool get_partition_id_range(partition_info *part_info,
 
 
 /*
-  Find the part of part_info->range_int_array that covers the given interval
-  
+  Find the sub-array of part_info->range_int_array that covers given interval
+ 
   SYNOPSIS 
     get_partition_id_range_for_endpoint()
       part_info         Partitioning info (partitioning type must be RANGE)
@@ -2607,9 +2608,9 @@ bool get_partition_id_range(partition_info *part_info,
                         interval
 
   DESCRIPTION
-    This function finds the part of part_info->range_int_array where the
+    This function finds the sub-array of part_info->range_int_array where the
     elements have non-empty intersections with the given interval.
-    
+ 
     A range_int_array element at index idx represents the interval
       
       [range_int_array[idx-1], range_int_array[idx]),
@@ -2617,14 +2618,13 @@ bool get_partition_id_range(partition_info *part_info,
     intervals are disjoint and ordered by their right bound, so
     
     1. For [a; +inf) or (a; +inf)-type intervals (left_endpoint==TRUE), the
-       sought array part starts at some index idx and continues till array 
-       end.
+       sought sub-array starts at some index idx and continues till array end.
        The function returns first number idx, such that the interval
        represented by range_int_array[idx] has non empty intersection with 
        the passed interval.
        
     2. For (-inf; a] or (-inf; a)-type intervals (left_endpoint==FALSE), the
-       sought array part starts at array start and continues till some last 
+       sought sub-array starts at array start and continues till some last
        index idx.
        The function returns first number idx, such that the interval
        represented by range_int_array[idx] has EMPTY intersection with the
@@ -2634,7 +2634,7 @@ bool get_partition_id_range(partition_info *part_info,
        returned.
        
   RETURN
-    The edge of corresponding part_info->range_int_array part.
+    The edge of corresponding part_info->range_int_array sub-array.
 */
 
 uint32 get_partition_id_range_for_endpoint(partition_info *part_info,
@@ -2645,6 +2645,7 @@ uint32 get_partition_id_range_for_endpoint(partition_info *part_info,
   longlong *range_array= part_info->range_int_array;
   uint max_partition= part_info->no_parts - 1;
   uint min_part_id= 0, max_part_id= max_partition, loc_part_id;
+  /* Get the partitioning function value for the endpoint */
   longlong part_func_value= part_info->part_expr->val_int();
   while (max_part_id > min_part_id)
   {

sql/table.h

@@ -297,6 +297,7 @@ struct st_table {
   FILESORT_INFO sort;
 #ifdef WITH_PARTITION_STORAGE_ENGINE
   partition_info *part_info;            /* Partition related information */
+  bool no_partitions_used; /* If true, all partitions have been pruned away */
 #endif
 
   bool fill_item_list(List<Item> *item_list) const;