The Apache Calcite PMC is pleased to announce Apache Calcite release 1.28.0.
This release comes four months after 1.27.0, contains contributions from 38 authors, and resolves 76 issues. New features include the UNIQUE sub-query predicate, the MODE aggregate function, PERCENTILE_CONT and PERCENTILE_DISC inverse distribution functions, an Exasol dialect for the JDBC adapter, and improvements to materialized view recognition.
This release contains some breaking changes (described below) due to the replacement of ImmutableBeans with Immutables. Two APIs are deprecated and will be removed in release 1.29.
Breaking changes to ImmutableBeans
In 1.28, Calcite converted the recently introduced configuration system from an internal system based on ImmutableBeans to instead use the Immutables annotation processor. This library brings a large number of additional features that should make value-type classes in Calcite easier to build and leverage. It also reduces reliance on dynamic proxies, which should improve performance and reduce memory footprint. Lastly, this change increases compatibility with ahead-of-time compilation technologies such as GraalVM. As part of this change, a number of minor changes have been made and key methods and classes have been deprecated. The change was designed to minimize disruption to existing consumers of Calcite but the following minor changes needed to be made:
field is now deprecated. To create a new configuration subclass, you
can either use your preferred interface-implementation based
construction or you can leverage Immutables. To do the latter,
configure your project
to use the Immutables annotation processor and annotate your
subclass with the
RelRule.Configsubclasses were nested 2+ classes deep, the interfaces have been marked deprecated and are superceded by new, uniquely named interfaces. The original Configs extend the new uniquely named interfaces. Subclassing these work as before and the existing rule signatures accept any previously implemented Config implementations. However, this is a breaking change if a user stored an instance of the
DEFAULTobject using the Config class name (as the
DEFAULTinstance now only implements the uniquely named interface).
RelRule.Config.as()method should only be used for safe downcasts. Before, it could do arbitrary casts. The exception is that arbitrary
as()will continue to work when using the deprecated
RelRule.Config.EMPTYfield. In most cases, this should be a non-breaking change. However, all Calcite-defined
DEFAULTrule config instances use Immutables. As such, if one had previously subclassed a
RelRule.Configsubclass and then used the
DEFAULTinstance from that subclass, the
as()call will no longer work to coerce the
DEFAULTinstance into a arbitrary subclass. In essence, outside the
as()is now only safe to do if a Java cast is also safe.
ValuesReduceRule.Confignow declare concrete bounds for their matchHandler configuration. This is a breaking change if one did not use the Rule as a bounding variable.
- Collections used in Immutables value classes will be converted to
Immutable collection types even if the passed in parameter is
mutable (such as an
ArrayList). As such, consumers of those configuration properties cannot mutate the returned collections.
See the release notes; download the release.