lance-format/lance

Add optimizer rule to change `LanceScanExec -> FilterExec` into `FilteredReadExec`

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#5,154 opened on Nov 6, 2025

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Description

There are query plans like this one that could benefit from pushing down the filter:

https://github.com/lancedb/lance/blob/35a0547426c47dd94425619c442dcd03ffd9860c/rust/lance/src/dataset/scanner.rs#L7157-L7158

Note: this will become obsolete if we change Scanner to construct a logical plan using the LanceTableProvider since pushdown can be handled at that layer. However, that's a ways off.

https://github.com/lancedb/lance/blob/35a0547426c47dd94425619c442dcd03ffd9860c/rust/lance/src/datafusion/dataframe.rs#L147-L158

Contributor guide

Research direction
Examine the referenced code at scanner.rs lines 7157-7158 and dataframe.rs lines 147-158 to understand the current execution plan. Study DataFusion's optimizer rule pattern to implement a new rule that combines LanceScanExec and FilterExec into FilteredReadExec, pushing down the filter condition. Ensure the rule doesn't break when no filter is present.
Tech stack
rust
Domain
backenddatabase
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75