Druid 0.12.2 release notes

[jihoonson]

DRAFT

Druid 0.12.2 contains stability improvements and bug fixes from 13 contributors. Major improvements include:

• More stable Kafka indexing service
• More stable data ingestion
• More stable segment balancing
• Bug fixes in querying and result caching

The full list of changes is here: https://github.com/apache/incubator-druid/pulls?q=is%3Apr+milestone%3A0.12.2+is%3Aclosed

Documentation for this release is at: http://druid.io/docs/0.12.2-rc1

Highlights

More stable Kafka indexing service

We have fixed a bunch of bugs in Kafka indexing service, which are mostly race conditions when incrementally publishing segments.

Added by @jihoonson in #5805.
Added by @surekhasaharan in #5899.
Added by @surekhasaharan in #5900.
Added by @jihoonson in #5905.
Added by @jihoonson in #5907.
Added by @jihoonson in #5996.

More stable data ingestion

We also have fixed some bugs in general data ingestion logics. Especially we have fixed a bug of wrong segment data when you use auto encoded long columns with any compression.

Added by @jihoonson in #5932.
Added by @clintropolis in #6045.

More stable segment balancing

Coordinator is now capable of more stable segment management especially for segment balancing. We have fixed an unexpected segment imbalancing caused by the conflicted decisions of Coordinator rule runner and balancer.

Added by @clintropolis in #5528.
Added by @clintropolis in #5529.
Added by @clintropolis in #5532.
Added by @clintropolis in #5555.
Added by @clintropolis in #5591.
Added by @clintropolis in #5888.
Added by @clintropolis in #5928.

Bug fixes in querying and result caching

We've fixed the wrong lexicographic sort of topN queries and the wrong filter application for the nested queries. The bug of ClassCastException when caching topN queries with Float dimensions has also fixed.

Added by @drcrallen in #5650.
Added by @gianm in #5653.

And much more!

The full list of changes is here: https://github.com/apache/incubator-druid/pulls?q=is%3Apr+milestone%3A0.12.2+is%3Aclosed

Updating from 0.12.1 and earlier

0.12.2 is a minor release and compatible with 0.12.1. If you're updating from an earlier version than 0.12.1, please see release notes of the relevant intermediate versions for additional notes.

Credits

Thanks to everyone who contributed to this release!

@acdn-ekeddy
@awelsh93
@clintropolis
@drcrallen
@gianm
@jihoonson
@jon-wei
@kaijianding
@leventov
@michas2
@Oooocean
@samarthjain
@surekhasaharan