A longstanding enhancement for snapshot isolation support for PostgreSQL is now here! A new connector configuration property, snapshot.isolation.mode, allows the connector to control the consistency used while executing the initial and ad-hoc blocking snapshot steps. There are four isolation levels: serializable (the default), repeatable_read, read_committed, and read_uncommitted. You can find details about these isolation levels and how they work with PostgreSQL in the documentation (DBZ-1252).

The JDBC sink uses a set of buffers to improve the throughput writes to the target database. In some use cases, the flush operation of these buffers may face specific exceptions due to locks due to other applications that may have locked a specific row or table. To improve the user experience, two new configuration properties have been added:

The retry feature is enabled by default, attempting to retry up to a maximum 5 attempts, with a 1-second delay between retries. If you prefer retries disabled, setting flush.failure.max.retries to 0 would disable this feature (DBZ-7291).

Oracle extended strings is a feature that allows the traditional 4000 byte limit on character data to be raised to 32K. This is done by applying a database upgrade to set the database parameter max_string_size to EXTENDED. The extended string feature then allows using the same SQL syntax used for 4000 byte or smaller character data to be used for character data up to 32K without forcing you to use CLOB-based operations.

With Debezium 3, you can now use the Oracle connector with databases that use extended strings and capture the changes directly from the transaction logs (DBZ-8039). As extended strings are effectively CLOB operations on the database level, mining such column types require setting lob.enabled to true.

As this new feature is experimental, we’d love to hear any feedback from the community!

In some cases, Oracle users may define tables with a CLOB or BLOB as required, using the EMPTY_BLOB() or EMPTY_CLOB() function to define a default when the field isn’t supplied. In previous builds, these special functions were not evaluated by Debezium, and such columns would have been emitted as optional rather than not optional.

Starting with Debezium 3, when an EMPTY_BLOB() or EMPTY_CLOB() default value is specified, the field will be emitted as not optional. Additionally, the field contain the appropriate default value, an empty byte array or an empty string respectively (DBZ-8248).