DataFusion weekly project plan (Andrew Lamb) - July 15, 2024

[alamb]

My (personal) North ⭐ : 1000 projects are built using DataFusion 📈

It would be great for other contributors to DataFusion to to make them visible somehow as well 🙏 (feel free to copy / modify the format of this ticket)

Externally Facing News

• DataFusion Belgrade Meetup 2024/09/27 #11431
• New York, NY, USA DataFusion Meetup: Tuesday Sep 17th 2024, 5:30PM - 8:30PM Manhattan #11213
• See discussion of roadmap: 2024 Q3-Q4 Roadmap? #11442
• Expr --> SQL is now optionally much prettier: Implement prettier SQL unparsing (more human readable) #11186 thanks to @MohamedAbdeen21
• @dharanad moved [Epic] Complete pulling out special SQL planning from the Sql Parser #11207 close to complete ❤

Feature Highlights

• between @Lordworms and @Blizzara substrait support is quite complete now (see integrate consumer tests, implement tpch query 18 to 22 #11462)
• CSE is getting even better thanks to @peter-toth: Improve CommonSubexprEliminate rule with surely and conditionally evaluated stats #11357
• DataFusion can make MAP scalars now: Implement ScalarFunction MAKE_MAP and MAP #11361 thanks to @goldmedal

My (personal) plans for this week

• [EPIC] Improve examples to make them easier to navigate #11172 Blog post with DataFusion Jan - June 2024 #9602,
• (Fun Project): Faster multi-column aggregation

Project Queue (list of future projects)

Projects I plan to help actively help review / push forward

• Help complete [EPIC] Continued correct and improved extracting Parquet statistics into ArrayRefs  #10922 @efredine has Add parquet StatisticsConverter for arrow reader arrow-rs#6046
• Complete SQL planner extension API Discussion: make it easier for specify SQL --> function translation #10534 with @jayzhan211 and @samuelcolvin, @xinlifoobar, @dharanad)
• Various upstream parquet metadata changes: Add ParquetMetadataWriter allow ad-hoc encoding of ParquetMetadata arrow-rs#6000, Do not write ColumnIndex for null columns when not writing page statistics arrow-rs#6011, Add size statistics to ParquetMetaData introduced in PARQUET-2261 arrow-rs#5486,
• Help push user defined aggregates over the line ([Epic] Unify AggregateFunction Interface (remove built in list of AggregateFunction s), improve the system #8708) - thanks to @Rachelint and @jcsherin)
• [EPIC] Implement StringViewArray and BinaryViewArray arrow-rs#5374 and [Epic] Implement support for StringView in DataFusion #10918 with @XiangpengHao and others

Algorithm for (my) prioritizing PR reviews

Note there are many committers who can and do review and merge PRs, so this is not the priorities of the project as a whole, just the approximate algorithm I use to prioritize my own time.

Priority:

1. Bug fixes (where something is just incorrect), especially regressions (where it used to work and now does not)
2. Improvements directly related to features needed for InfluxDB (my employer)
3. Documentation and test improvements (I view these as very strategically important)
4. PRs for other features I think are strategically important (See below)
5. Other new features / additions to functionality (note this is the lowest on purpose)

The top strategically important projects in my head are:

• Anything that makes it easier to use DataFusion as a user (docs, examples, better APIs, etc), including Getting started guide for new users (who want to use DataFusion in their project)
• Anything that improves DataFusion's quality such as bug fixes, and improved / expanded tests, etc
• Improved performance (with benchmarks)

Thus, if you are interested in contributing to DataFusion and are interested in a fast turn around time I would recommend looking into bug fixes / test improvements / documentation or the projects named above.

If you propose adding new functionality, especially if the PR is large/complex and not connected to a wider need, the review cycle will likely be longer. You can make it a shorter cycle by looking at the comments on other recent PRs and following the same model (e.g. ensure there are tests in sqllogictest for example, the CI passes, includes documentation, etc)

Background

The idea of this ticket is make my plans for DataFusion visible, largely for my own personal organizational needs, but also to:

1. Communicate / coordinate in the community
2. Help provide an interesting summary of what is happening in DataFusion this week

[alamb]

Review Queue

Arrow

• Implement min max support for string/binary view types arrow-rs#6053
• Add parquet StatisticsConverter for arrow reader arrow-rs#6046
• Fix some unsound unsafe code in arrow and attempt to improve safety docs. arrow-rs#6021

DataFusion:

• upgrade sqlparser 0.47 -> 0.48 #11453
• Minor: fix some new warnings, fix force_hash_collisions flag propagation + comment out some tests #11467
• Support SortMergeJoin spilling #11218
• feat: support COUNT() #11229
• [Proposal] Decouple logical from physical types #11513
• Plan LATERAL subqueries #11456
• Add parser option enable_options_value_normalization #11330
• Extract parquet statistics for StructArray #11289
• Introduce the DynamicFileCatalog in datafusion-catalog #11035
• Feat: Implement hf:// / "hugging face" integration in datafusion-cli #10792

[alamb]

Arrow:

• Consistent naming for Parquet page index structures arrow-rs#6097
• Fix some unsound unsafe code in arrow and attempt to improve safety docs. arrow-rs#6021

[alamb]

Next week: #11601