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, 12 insertions, 0 deletions

diff --git a/mysql-test/t/temp_table.test b/mysql-test/t/temp_table.test
index 6b3991c9c78..2d505fdfece 100644
--- a/mysql-test/t/temp_table.test
+++ b/mysql-test/t/temp_table.test
@@ -115,3 +115,15 @@ select d, c from t1 left join t2 on b = c where a = 3 order by d;
 drop table t1, t2;
 
 # End of 4.1 tests
+
+#
+# Test truncate with temporary tables
+#
+
+create temporary table t1 (a int);
+insert into t1 values (4711);
+select * from t1;
+truncate t1;
+insert into t1 values (42);
+select * from t1;
+drop table t1;