Add release notes for 0.67
[maven-release-plugin] prepare release 0.67
[maven-release-plugin] prepare for next development iteration
Don't double count bytes and rows in RecordProjectOperator
Fix release notes for 0.67
Fix warnings in HiveBucketing
Fix handling of Hive tables bucketed on string
Add 0.68 release notes
Fix Hive bucketing test
[maven-release-plugin] prepare release 0.68
[maven-release-plugin] prepare for next development iteration
Increase parallelism in unit tests to 4
Add timestamp with time zone minus interval year month operator
Support explaining sampled queries
Move drop table logic to NativeMetadata
Static import query execution factories
Used shared executor for query execution
Rename InMemoryMetadata to TestingMetadata
Remove useless check in NativeMetadata
Use checkType in NativeMetadata