v0.9.9: DDL & Schema evolution for LogMiner source

The following Data Definition Language (DDL) clauses of ALTER TABLE command are currently supported:

1. add column(s)
2. modify column(s)
3. drop column(s)
4. rename column
5. set unused column(s)

To ensure compatibility with Schema Evolution the following algorithm is used:

1. When oracdc first encounters an operation on a table in the redo logs, information about the table is read from the data dictionary or from the JSON file specified by the a2.dictionary.file parameter. Two schemas are created: immutable key schema with unique identifier [PDB_NAME:]OWNER.TABLE_NAME.Key, version=1 and mutable value schema with unique identifier [PDB_NAME:]OWNER.TABLE_NAME.Value, version=1.
2. After successful parsing of DDL and comparison of columns definition before and after, value schema gets an incremented version number.