Table definition cache, part 2

The table opening process now works the following way:
- Create common TABLE_SHARE object
- Read the .frm file and unpack it into the TABLE_SHARE object
- Create a TABLE object based on the information in the TABLE_SHARE
  object and open a handler to the table object

Other noteworthy changes:
- In TABLE_SHARE the most common strings are now LEX_STRING's
- Better error message when table is not found
- Variable table_cache is now renamed 'table_open_cache'
- New variable 'table_definition_cache' that is the number of table defintions that will be cached
- strxnmov() calls are now fixed to avoid overflows
- strxnmov() will now always add one end \0 to result
- engine objects are now created with a TABLE_SHARE object instead of a TABLE object.
- After creating a field object one must call field->init(table) before using it

- For a busy system this change will give you:
 - Less memory usage for table object
 - Faster opening of tables (if it's has been in use or is in table definition cache)
 - Allow you to cache many table definitions objects
 - Faster drop of table

1 files changed, 4 insertions, 1 deletions

diff --git a/sql/item_create.cc b/sql/item_create.cc
index 342ef245a76..e8435be2614 100644
--- a/sql/item_create.cc
+++ b/sql/item_create.cc
@@ -462,7 +462,6 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
 		       CHARSET_INFO *cs)
 {
   Item *res;
-  LINT_INIT(res);
 
   switch (cast_type) {
   case ITEM_CAST_BINARY: 	res= new Item_func_binary(a); break;
@@ -478,6 +477,10 @@ Item *create_func_cast(Item *a, Cast_target cast_type, int len, int dec,
     res= new Item_char_typecast(a, len, cs ? cs : 
 				current_thd->variables.collation_connection);
     break;
+  default:
+    DBUG_ASSERT(0);
+    res= 0;
+    break;
   }
   return res;
 }