Outer joins cleanup: Remove TABLE::outer_join and use TABLE::maybe_null only...

Outer joins cleanup: Remove TABLE::outer_join and use TABLE::maybe_null only (2nd patch after Monty's comments).

sql/mysql_priv.h

@@ -1329,7 +1329,7 @@ inline void setup_table_map(TABLE *table, TABLE_LIST *table_list, uint tablenr)
   table->null_row= 0;
   table->status= STATUS_NO_RECORD;
   table->keys_in_use_for_query= table->s->keys_in_use;
-  table->maybe_null= test(table->outer_join= table_list->outer_join);
+  table->maybe_null= table_list->outer_join;
   table->tablenr= tablenr;
   table->map= (table_map) 1 << tablenr;
   table->force_index= table_list->force_index;

sql/opt_range.cc

@@ -3611,7 +3611,7 @@ get_mm_leaf(PARAM *param, COND *conf_func, Field *field, KEY_PART *key_part,
 
   if (!value)					// IS NULL or IS NOT NULL
   {
-    if (field->table->outer_join)		// Can't use a key on this
+    if (field->table->maybe_null)		// Can't use a key on this
       DBUG_RETURN(0);
     if (!maybe_null)				// Not null field
       DBUG_RETURN(type == Item_func::ISNULL_FUNC ? &null_element : 0);

sql/sql_base.cc

@@ -854,7 +854,7 @@ TABLE *reopen_name_locked_table(THD* thd, TABLE_LIST* table_list)
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->outer_join= table->null_row= table->maybe_null= table->force_index= 0;
+  table->null_row= table->maybe_null= table->force_index= 0;
   table->status=STATUS_NO_RECORD;
   table->keys_in_use_for_query= share->keys_in_use;
   table->used_keys= share->keys_for_keyread;
@@ -1078,7 +1078,7 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->outer_join= table->null_row= table->maybe_null= table->force_index= 0;
+  table->null_row= table->maybe_null= table->force_index= 0;
   table->status=STATUS_NO_RECORD;
   table->keys_in_use_for_query= table->s->keys_in_use;
   table->insert_values= 0;
@@ -1150,7 +1150,6 @@ bool reopen_table(TABLE *table,bool locked)
   tmp.tablenr=		table->tablenr;
   tmp.used_fields=	table->used_fields;
   tmp.const_table=	table->const_table;
-  tmp.outer_join=	table->outer_join;
   tmp.null_row=		table->null_row;
   tmp.maybe_null=	table->maybe_null;
   tmp.status=		table->status;

sql/sql_select.cc

@@ -9181,7 +9181,7 @@ join_read_const_table(JOIN_TAB *tab, POSITION *pos)
       tab->info="const row not found";
       /* Mark for EXPLAIN that the row was not found */
       pos->records_read=0.0;
-      if (!table->outer_join || error > 0)
+      if (!table->maybe_null || error > 0)
 	DBUG_RETURN(error);
     }
   }
@@ -9200,7 +9200,7 @@ join_read_const_table(JOIN_TAB *tab, POSITION *pos)
       tab->info="unique row not found";
       /* Mark for EXPLAIN that the row was not found */
       pos->records_read=0.0;
-      if (!table->outer_join || error > 0)
+      if (!table->maybe_null || error > 0)
 	DBUG_RETURN(error);
     }
     if (table->key_read)

sql/table.h

@@ -217,14 +217,18 @@ struct st_table {
   uint          derived_select_number;
   int		current_lock;           /* Type of lock on table */
   my_bool copy_blobs;			/* copy_blobs when storing */
+  
+  /* 
+    0 or JOIN_TYPE_{LEFT|RIGHT}. Currently this is only compared to 0.
+    If maybe_null !=0, this table is inner w.r.t. some outer join operation,
+    and null_row may be true.
+  */
+  uint maybe_null;
   /*
-    Used in outer joins: if true, all columns are considered to have NULL
-    values, including columns declared as "not null".
+    If true, the current table row is considered to have all columns set to 
+    NULL, including columns declared as "not null" (see maybe_null).
   */
   my_bool null_row;
-  /* 0 or JOIN_TYPE_{LEFT|RIGHT}, same as TABLE_LIST::outer_join */
-  my_bool outer_join;
-  my_bool maybe_null;                   /* true if (outer_join != 0) */
   my_bool force_index;
   my_bool distinct,const_table,no_rows;
   my_bool key_read, no_keyread;