The DDL parser and in-memory models of the relational schemas were changed to capture the character set for each column whose type is a string (e.g., `CHAR`, `VARCHAR`, etc.). This required handling `SET` statements used to change the system variables that hold the names of the default character set for the server and for each database. So, even if a column does not explicitly define the character set, the column's actual character set is identified from the table's character set, which might default to the current database's character set, which if not set defaults to the system character set.
These changes merely affect how MySQL DDL is parsed and the in-memory relational schema representation to accommodate the character set at various levels. It does not change the behavior of the MySQL connector; that will be done in a subsequent commit.
All tests pass with these changes, including quite a few additional tests for the new functionality.
257e81c540