Add direct aggregates

Spider patches 026 (MDEV-7723), 031 (MDEV-7727) and 058 (MDEV-12532)

This allows the storage engine to internally compute sum and count
operations.

- Enhance sum items to be able to store the sum value directly.
- return_record_by_parent() is enabled in spider as
  HANDLER_HAS_DIRECT_AGGREGATE is defined
- Added spd_environ.h to spider. This is loaded first to ensure that all
  MariaDB specific defines that are used by include files are properly
  defined.
- This code is tested by the existing spider tests direct_aggregate.test
  and direct_aggregate_part.test and also partition.test

mysql-test/r/partition.result

@@ -513,6 +513,9 @@ COUNT(*)
 SELECT SUM(c) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
 SUM(c)
 400
+SELECT SUM(c+0.0) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
+SUM(c+0.0)
+400.0
 ALTER TABLE t1 DROP INDEX b;
 SELECT COUNT(*) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
 COUNT(*)

mysql-test/t/partition.test

@@ -445,6 +445,7 @@ INSERT INTO t1 VALUES (1,1,0), (1,1,1), (1,1,2), (1,1,53), (1,1,4), (1,1,5),
 (1,19,1);
 SELECT COUNT(*) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
 SELECT SUM(c) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
+SELECT SUM(c+0.0) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
 ALTER TABLE t1 DROP INDEX b;
 SELECT COUNT(*) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );
 SELECT SUM(c) FROM t1 WHERE b NOT IN ( 1,2,6,7,9,10,11 );

sql/ha_partition.cc

@@ -4212,7 +4212,6 @@ int ha_partition::write_row(uchar * buf)
   sql_mode_t saved_sql_mode= thd->variables.sql_mode;
   bool saved_auto_inc_field_not_null= table->auto_increment_field_not_null;
   DBUG_ENTER("ha_partition::write_row");
-  DBUG_ASSERT(buf == m_rec0);
 
   /*
     If we have an auto_increment column and we are writing a changed row

sql/handler.h

@@ -3499,7 +3499,7 @@ class handler :public Sql_alloc
     return 0;
   }
   virtual void set_part_info(partition_info *part_info) {return;}
-  virtual void return_record_by_parent() {return;}
+  virtual void return_record_by_parent() { return; }
 
   virtual ulong index_flags(uint idx, uint part, bool all_parts) const =0;
 

sql/item.h

@@ -5848,6 +5848,7 @@ class Item_cache: public Item_basic_constant,
   }
 
   virtual void store(Item *item);
+  virtual Item *get_item() { return example; }
   virtual bool cache_value()= 0;
   bool basic_const_item() const
   { return MY_TEST(example && example->basic_const_item()); }