DataFusion weekly project plan (Andrew Lamb) - June 24, 2024

[alamb]

Follow on to #10955

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

• Meetup in SF organized by @cpard and @emgeee: DISCUSSION: DataFusion Meetup in San Francisco Bay Area USA #10340
• Meetup in China being organized in July by @waynexia and @tisonkun : DISCUSSION: DataFusion Meetup in China #10341 (comment)

Feature Highlights

• Support long requested API: Support parsing SQL strings to Exprs #10995 (thanks @xinlifoobar!)
• Work to support StringView has begun in earnest (thanks to @XiangpengHao, @PsiACE and @Weijun-H
• Converting SQL --> String is getting close to complete (thanks @goldmedal,
• @2010YOUY01 started testing DataFusion with SQLancer and found several bugs. Kudso to @LorrensP-2158466 for fixing a bunch of them already!
• @Omega359 added nice DataFrame APIs: DataFrame::drop_column and DataFrame::distinct_on
• Consider timezones with UTC and +00:00 to be the same #10960 (Thanks @marvinlanhenke and @samuelcolvin!)
• Parquet statistics are looking pretty good thanks to @tshauck, @marvinlanhenke and @LorrensP-2158466 @tmi
• We are in the final phases of converting all aggregate functions -- thanks to this from @dharanad and others
• Merged Advanced example for building an external index for Row Groups *within* parquet files #10580

My (personal) plans for this week

• Present at DataFusion Meetup in SF (slides)
• Presentation about DataFusion at Microsoft GSL (Gray Systems Lab) #10969
• July 10, 2024 ASF Board Report #10282
• Return TableProviderFilterPushDown::Exact when Parquet Pushdown Enabled #4028
• Blog post with DataFusion Jan - June 2024 #9602
• Check out @Max-Meldrum's example index from Indexing Support in DataFusion? #9963 (reply in thread)
• Help @jayzhan211 with faster multi-column aggregation Improve performance for grouping by variable length columns (strings) #9403 (needs some optimizer work)

Project Queue (list of future projects)

Projects I plan to help actively help review / plan

• [EPIC] Implement StringViewArray and BinaryViewArray arrow-rs#5374 with @XiangpengHao and others
• [EPIC] Continued correct and improved extracting Parquet statistics into ArrayRefs  #10922 (with @marvinlanhenke @Weijun-H 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 that I think are strategically important
5. Other new features / additions to functionality (note this is the lowest)

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
• Making function packages modular and easier to mix/match
• 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:

• Introduce the DynamicFileCatalog in datafusion-catalog #11035
• Array agg groups accumulator, second attempt #11096
• Feat: Implement hf:// / "hugging face" integration in datafusion-cli #10792
• Custom operator support #11137

Arrow

• Provide Arrow Schema Hint to Parquet Reader - Alternative 2 arrow-rs#5939

[alamb]

DataFusion

• [draft] Add LogicalType, try to support user-defined types #11160

Arrow

• Add size statistics to ParquetMetaData introduced in PARQUET-2261 arrow-rs#5486

[alamb]

Next week: #11190