lance-format / lance-format/lance

Merge with more than a single column for `left_on` possible?

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enhancement good first issue rust
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Rust
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Description

@eddyxu @changhiskhan I had asked about adding columns in #767 and implementing this got put on hold, but now I have some questions.

Is the left_on and right_on only able to select a single column (it seems so)? We typically have datasets with inference_date and id, where for each day (inference_date there are multiple overlapping ids. We could make a column like date_id and join those two columns together to be able to do the merge. I am just checking if this feature will ever be possible or how best to design this from our end.

Thanks!

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Research direction

No source files, tests, or entry points are named. Start by reviewing the related discussion in issue #767 and the current merge behavior, then clarify how multi-column left_on and right_on should work for inference_date and id before defining acceptance tests.

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Assessment

Tech stack
rust
Domain
data-engineering
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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