lance-format/lance

refactor: use LazyLock to initialize Field and Schema once

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#8,244 opened on Aug 4, 2026

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good first issue

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Description

In many places we output the same set of fields and/or schema per method call, or even per batch. This can be made cheaper if we initialize them once via a LazyLock and wrapping in an Arc.

Here's an example where we construct a schema per query:

https://github.com/lance-format/lance/blob/11eeb29161a2ac2763ff8cc6aa1fde8eb4592291/rust/lance-index/src/scalar/inverted/index.rs#L8107-L8116

Contributor guide

Research direction
Review the linked code example to see how Field and Schema are constructed per query. Then search the codebase for similar repeated initializations. Understand LazyLock and Arc to store a once initialized shared instance.
Tech stack
rust
Domain
backend
Issue type
Refactor
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
GitRust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75