CDC Guide for Linux, UNIX, and Windows

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MySQL CDC Operational Considerations

Review the following operational considerations for MySQL CDC:

PowerExchange is certified with MySQL source databases that use the InnoDB storage engine. PowerExchange is not certified with the other types of storage engines that MySQL can use.

PowerExchange does not support MySQL database deployed in a cloud environment.

PowerExchange can capture change data from table spaces that use InnoDB tablespace encryption and from InnoDB tables that use Transparent Data Encryption (TDE).

PowerExchange uses the MySQL mysqlbinlog utility to read change events from MySQL binary log files. Do not delete the binary log files until the PowerExchange has completed log file processing. If you delete the log files, PowerExchange might miss some change events.

After you run CDC sessions that extract change data for MySQL sources, avoid changing the base name of the binary log files or the name or location of the directory that contains the binary log files to minimize the potential for change data loss. If you must change the binary log location or base name, see Changing the Binary Log Location or Base Name.

When reading the binary log file, if the binary log reader encounters a DDL event that changes a registered MySQL source table, capture processing usually ends with an error. PowerExchange recognizes and reacts to the following DDL events:

DDL	PowerExchange Reaction
TRUNCATE TABLE	If the ONTABLETRUNC parameter in the MYSQL CAPI_CONNECTION statement is set to FAIL, capture processing ends. If the ONTABLETRUNC parameter is set to WARN, PowerExchange issues a warning message and continues CDC processing with the next change record.
CREATE TABLE	If you are not using the PowerExchange Logger, capture processing continues and ignores the table. If you are using the PowerExchange Logger, the Logger continues to run if the table was not previously registered. If the table was previously registered and then re-created, the Logger ends.
DROP TABLE	Capture processing ends with an error.
RENAME TABLE	Capture processing ends with an error.
ALTER TABLE RENAME COLUMN	Capture processing ends with an error.
ALTER TABLE ADD COLUMN	Capture processing continues.
ALTER TABLE DROP COLUMN	Capture processing ends with an error.
ALTER TABLE CHANGE COLUMN	Capture processing ends with an error.

You cannot create capture registrations for MySQL source tables that include one or more columns with a spatial datatype, such as GEOMETRY. Consequently, PowerExchange cannot capture change data from these tables.

If MySQL source tables contain native JSON columns with binary data, PowerExchange converts the JSON binary data to a textual representation for CDC processing.

In PowerExchange, you cannot register MySQL source tables that contain one or more columns that are defined with the any of the following character sets:

Character Set	Description
amrscii8	ARMSCII-8 Armenian
binary	Binary pseudo charset
dec8	DEC West European
eucjpms	UJIS for Windows Japanese
geostd8	GEOSTD8 Georgian
hp8	HP West European
keybcs2	DOS Kamenicky Czech-Slovak
koi8u	IOI8-U Ukrainian
swe7	7-bit Swedish

When the mysqlbinlog utility tries to connect to a remote binary log, MySQL passes the MySQL password that is required for connection as clear text. The password is then visible to any tools that list executing processes and their startup parameters.

When the mysqlbinlog utility reads a remote binary log, it opens a connection to the MySQL server using a specific server ID, as specified in the server-id option. PowerExchange uses the server-id of 369 to connect to MySQL for change data extraction. Ensure that no other tool or application uses the server-id of 369 to access MySQL. Also, ensure that only one CDC session is active at a time.

PowerExchange uses the DataDirect ODBC driver for MySQL to connect to MySQL source databases. You can define the ODBC_CONN_PARAMS statement in the dbmover.cfg file If you want to add ODBC parameters to the connection strings that are used on the servers you specify for the following processing:

Change data capture

Creating, deleting, or modifying capture registrations from the PowerExchange Navigator or DBLUCBRG utility

For example, you might need to add ODBC parameters if your site policies require database connections to use SSL encryption, specific cryptographic protocols, or self-signed or third-party signed SSL certificates. For more information, see the PowerExchange Reference Manual
.

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