MDEV-15777 Use inferred IS NOT NULL predicates in the range optimizer10.3-mdev15777

This patch introduces the optimization that allows range optimizer to
consider index range scans that are built employing NOT NULL predicates
inferred from WHERE conditions and ON expressions.
The patch adds a new optimizer switch not_null_range_scan.

1 files changed, 22 insertions, 0 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index 6345dd41f71..325a79600e9 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -210,6 +210,7 @@ public:
   void traverse_cond(Cond_traverser traverser,
                      void * arg, traverse_order order);
   bool eval_not_null_tables(void *opt_arg);
+  bool find_not_null_fields(table_map allowed);
  // bool is_expensive_processor(void *arg);
  // virtual bool is_expensive() { return 0; }
   inline void raise_numeric_overflow(const char *type_name)
@@ -671,6 +672,7 @@ public:
   Item_func_case_expression(THD *thd, List<Item> &list):
     Item_func_hybrid_field_type(thd, list)
   { }
+  bool find_not_null_fields(table_map allowed) { return false; }
 };
 
 
@@ -1759,6 +1761,10 @@ public:
     not_null_tables_cache= 0;
     return false;
   }
+  bool find_not_null_fields(table_map allowed)
+  {
+    return false;
+  }
   Item* propagate_equal_fields(THD *thd, const Context &ctx, COND_EQUAL *cond)
   { return this; }
   bool const_item() const { return true; }
@@ -2119,6 +2125,10 @@ public:
     not_null_tables_cache= 0;
     return 0;
   }
+  bool find_not_null_fields(table_map allowed)
+  {
+    return false;
+  }
   bool is_expensive() { return 1; }
   virtual void print(String *str, enum_query_type query_type);
   bool check_vcol_func_processor(void *arg)
@@ -2711,6 +2721,10 @@ public:
     not_null_tables_cache= 0;
     return 0;
   }
+  bool find_not_null_fields(table_map allowed)
+  {
+    return false;
+  }
   bool fix_fields(THD *thd, Item **ref);
   bool eq(const Item *, bool binary_cmp) const;
   /* The following should be safe, even if we compare doubles */
@@ -3000,6 +3014,10 @@ public:
     not_null_tables_cache= 0;
     return 0;
   }
+  bool find_not_null_fields(table_map allowed)
+  {
+    return false;
+  }
 };
 
 
@@ -3103,6 +3121,10 @@ public:
     not_null_tables_cache= 0;
     return 0;
   }
+  bool find_not_null_fields(table_map allowed)
+  {
+    return false;
+  }
   bool const_item() const { return 0; }
   void evaluate_sideeffects();
   void update_used_tables()