Nov 20. 2024: This week in DataFusion

[alamb]

Introduction

• Follow on to Nov 5. 2024: This week in DataFusion #13265
  This ticket is a weekly-ish summary of interesting things happening in DataFusion. Note this is not a complete list (it is what I remember / can find). Please feel free to leave comments on this ticket about things that I may have missed or you think should get wider attention by the community

Loosely inspired by https://this-week-in-rust.org/

Highlights

• 🚀 DataFusion 43 currently has the fastest results on ClickBench (blog coming soon)
• 📝 Completed [EPIC] Automatically generate all function documentation from code #12740. Thanks to @Omega359 and @jonathanc-n for driving the project to completion
• ⚒️ Completed [Epic] Unify WindowFunction Interface (remove built in list of BuiltInWindowFunction s) #8709 -- thanks @jcsherin @jatin510 for helping push it over the line

DataFusion Related Reading List

• Comparing approaches to User Defined Functions in Apache DataFusion using Python from @timsaucer
• New [Concepts, Readings, Events¶](https://datafusion.apache.org/user-guide/concepts-readings-events.html) page

Recent Releases

• Release DataFusion 42.2.0 #13166
• Release DataFusion 43.0.0 #12470 (thanks @andygrove)
• Release sqlparser-rs version 0.52.0 datafusion-sqlparser-rs#1423 (huge kudos to @iffyio for all the reviews)

Highlights from last week(s):

(I am sorry if I missed you -- please add a note to this ticket with anything you would like to highlight)

Performance

• @Rachelint completed Support vectorized append and compare for multi group by #12996 for another boost on ClickBench performance
• @jonathanc-n feat: Support faster multi-column grouping ( GroupColumn) for Date/Time/Timestamp types #13457

🐛 🔨

• @findepi fixed LIKE in various places Test LIKE with implicit \ escape #13288, Expand LIKE simplification: cover NULL pattern/expression and constant #13260
• Also fixed Produce informative error on physical schema mismatch #13434 and Fix invalid swap for LeftMark nested loops join #13426
• @findepi also fixed Fix join on arrays of unhashable types and allow hash join on all types supported at run-time #13388

Features

• @goldmedal added Introduce INFORMATION_SCHEMA.ROUTINES table #13255
• Also @goldmedal added Introduce information_schema.parameters table #13341
• Custom type planner (also from @goldmedal ): Introduce TypePlanner for customizing type planning #13294
• @jonahgao completed support for PREPARE and EXECUTE, in several PRs such as feat: basic support for executing prepared statements #13242 and refactor: move PREPARE/EXECUTE into LogicalPlan::Statement #13311

Logical Types

• @jayzhan211 is reworking signatures with Use LogicalType for TypeSignature Numeric and String, Coercible #13240 and Support TypeSignature::Nullary #13354

SortMergeJoin correctness and stability fixes(@comphead):

• Move filtered SMJ Full filtered join out of join_partial phase #13369
• Minor: SortMergeJoin small refactoring #13398

Aggregation testing coverage

• @jonathanc-n keep improving with PR after PR

Unparser (Plan --> String)

• @blaginin such as Allow aggregation without projection in Unparser #13326
• @goldmedal Support unparsing Array plan to SQL string #13418
• @Sevenannn Fix duckdb & sqlite character_length scalar unparsing #13428 and Fix Binary & Binary View Unparsing #13427
• @phillipleblanc in Support Utf8View in Unparser expr_to_sql #13462

Others

• @alamb started documenting how to use multiple threadpools, see Improve documentation (and ASCII art) about streaming execution, and thread pools #13423

Major Projects / Discussions under way

• [Epic] A Collection of Additional UTF8View support tickets #13504 with @timsaucer and @Omega359
• Release Minor DataFusion 43.1.0 release #13499 to try and get delta-rs updated

Looking to get more involved? Try code review!

DataFusion has a long history of community members contributing in all aspects of the project. Reviewing PRs is an especially great way to get introduced to the project, help the community and grow your own knowledge -- researching and understanding the code enough to review PRs also often inspires additional ideas for improvements.

We have docs about reviews. TLDR is: look for test coverage, if the change is understandable and well documented, and if the code can be improved. When you think the PR looks good to merge, try @ mentioning one of the committers.

Help wanted

Please feel leave your own comments on this ticket if you are looking for help

Community

• Weekly Call
• Slack/Discord: info links

Upcoming meetups:

• 2024 Dec 18 Chicago: https://lu.ma/eq5myc5i @adriangb @timsaucer
• DISCUSSION: January 2025 DataFusion Meetup in Amsterdam / CIDR 2025 #12988
• 2025 Jan 15 Boston

Background:

Previous update:

• Oct 28, 2024: This week in DataFusion #13167

Andrew's Focus Areas:

• Document DataFusion Threading / tokio runtimes (how to separate IO and CPU bound work) #12393

[alamb]

New blog posts:

• DataFusion Blog: Comparing approaches to User Defined Functions in Apache DataFusion using Python

• DataFusion Blog: Apache DataFusion Comet 0.4.0 Release

• Building Databases over a Weekend -- @ameyc ❤️ (thanks to @devanbenz for this link)

[alamb]

• Apache DataFusion is now the fastest single node engine for querying Apache Parquet files