[Draft] 0.18.1 Release notes

[jihoonson]

Apache Druid 0.18.1 is a bug fix release that fixes Streaming ingestion failure with Avro, ingestion performance issue, upgrade issue with HLLSketch, and so on. The complete list of bug fixes can be found at https://github.com/apache/druid/pulls?q=is%3Apr+milestone%3A0.18.1+label%3ABug+is%3Aclosed.

# Bug fixes

• Rollback kinesis lag metric for 0.18.1 #9823 rollbacks the new Kinesis lag metrics as it can stall the Kinesis supervisor indefinitely with a large number of shards.
• Initialize SettableByteEntityReader only when inputFormat is not null #9734 fixes the Streaming ingestion failure issue when you use a data format other than CSV or JSON.
• Fix filtering on boolean values in transformation #9812 fixes filtering on boolean values during transformation.
• Fix misuse of Integer.SIZE in FileWriteOutBytes.writeInt #9723 fixes slow ingestion performance due to frequent flushes on local file system.
• revert datasketches-java version to 1.1.0-incubating until new version is released #9751 reverts the version of datasketches-java from 1.2.0 to 1.1.0 to workaround upgrade failure with HLLSketch.
• fixes for inline subqueries when multi-value dimension is present #9698 fixes a bug in inline subquery with multi-valued dimension.
• fix issue where CloseableIterator.flatMap does not close inner CloseableIterator #9761 fixes a bug in CloseableIterator which potentially leads to resource leaks in Data loader.

# Known issues

Incorrect result of nested groupBy query on Join of subqueries

A nested groupBy query can result in an incorrect result when it is on top of a Join of subqueries and the inner and the outer groupBys have different filters. See #9866 for more details.

# Credits

Thanks to everyone who contributed to this release!

@clintropolis
@gianm
@jihoonson
@maytasm
@suneet-s
@viongpanzi
@whutjs