Add MySQL 5.7 column name support

[kartalbas]

Summary

This PR adds support for getting column names when using MySQL 5.7, which doesn't include column names in the binary log by default.

What Changed

• Added new option use_column_name_cache to enable column name fetching
• Fetches column names from INFORMATION_SCHEMA.COLUMNS when binlog metadata is missing
• Uses in-memory caching to avoid repeated database queries
• Only runs when explicitly enabled (opt-in feature)

Why This Is Needed

• MySQL 5.7 does not support binlog_row_metadata=FULL setting
• Without this feature, column names are unavailable in binlog events
• Many legacy applications still run on MySQL 5.7 and cannot upgrade due to operational constraints, infrastructure dependencies, or business requirements
• This feature enables these applications to continue using mysql-replication without requiring a database upgrade
• Applications need column names to properly process row change events

How It Works

• When use_column_name_cache=True is set, the library queries INFORMATION_SCHEMA for column names
• Results are cached to improve performance
• Falls back gracefully if the query fails
• Default behavior remains unchanged (feature is disabled by default)

Testing

Tested with MySQL 5.7 databases where binlog metadata is not available.

[julien-duponchelle]

Sorry you have a failure in the test :
pkt = <pymysql.protocol.MysqlPacket object at 0x00007f9b9fdcd2f0>

def create_binlog_packet_wrapper(pkt):
    return BinLogPacketWrapper(
        pkt,
        self.stream.table_map,
        self.stream._ctl_connection,
        self.stream.mysql_version,
        self.stream._BinLogStreamReader__use_checksum,
        self.stream._BinLogStreamReader__allowed_events_in_packet,
        self.stream._BinLogStreamReader__only_tables,
        self.stream._BinLogStreamReader__ignored_tables,
        self.stream._BinLogStreamReader__only_schemas,
        self.stream._BinLogStreamReader__ignored_schemas,
        self.stream._BinLogStreamReader__freeze_schema,
        self.stream._BinLogStreamReader__ignore_decode_errors,
        self.stream._BinLogStreamReader__verify_checksum,

      self.stream._BinLogStreamReader__optional_meta_data,

    )

E TypeError: init() missing 1 required positional argument: 'enable_logging'

test_basic.py:621: TypeError

(I know it's not easy to run the test :( )

[kartalbas]

thank you, is fixed - local it failes with "FAILED pymysqlreplication/tests/test_basic.py::TestBasicBinLogStreamReader::test_event_validation - pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on 'localhost' ([WinError 10061] No connection could be made because the target machine actively refused it)")" because in this machine I dont have amysql but the required fix is in the commit - hope it works now

[kartalbas]

can you please try again to merge? Im still using my branch in my fork

[julien-duponchelle]

I'm doing a release 1.0.11 with it

[julien-duponchelle]

Thanks a lot !