Document Sort Merge Join algorithm

apache / datafusion

Apache DataFusion SQL Query Engine

https://datafusion.apache.org/

Apache License 2.0

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Document Sort Merge Join algorithm #10357

Open comphead opened 2 weeks ago

comphead commented 2 weeks ago

Is your feature request related to a problem or challenge?

I faced that it is challenging to understand fully how Sort Merge Join sort_merge_join.rs implemented and would be nice to get it documented the same way as HashJoin in hash_join.rs

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

No response

comphead commented 2 weeks ago

Found when fixing SMJ bugs https://github.com/apache/datafusion/pull/10304

comphead commented 2 weeks ago

cc @korowa you might be interested

alamb commented 2 weeks ago

Maybe @metesynnada can help remember who knows about this code too

viirya commented 2 weeks ago

I spent some time reading and understanding the code last time I worked with it. I may try to document it some once I get time to refresh it...