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29 lines
1.6 KiB
Markdown
29 lines
1.6 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [commit, loop, transaction, lock, checkpoint, codeunit-run]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# Do not Commit inside loops
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> Contributions welcome — open a PR to refine or extend this article.
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## Description
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Commit ends the current write transaction. Calling it inside a per-row loop produces one transaction per iteration and loses the ability to roll back the whole operation atomically; it also interferes with the platform's ability to batch write operations. Most loops need no explicit Commit at all — AL auto-commits the enclosing code module on successful completion (see `understand-implicit-transaction-boundary.md`). When the batch is too large for one transaction, the fix is not a per-row Commit but bounded checkpoints that each process N rows.
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## Best Practice
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If the batch is large enough that a single transaction is untenable, process it in checkpoints driven by an outer loop that each time picks up the next N rows. Commit once per checkpoint at a clearly defined safe boundary, not inside the per-row loop. Wrapping each chunk in `Codeunit.Run` gives the same effect with native rollback on failure — see `codeunit-run-as-atomic-sub-operation.md`.
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See sample: `avoid-commit-inside-loops.good.al`.
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## Anti Pattern
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Placing Commit inside `repeat ... until Next() = 0` is almost always a mistake: it is unusual for the correctness of the operation to depend on per-row commits, and the cost of starting a new transaction on every row dominates the work.
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See sample: `avoid-commit-inside-loops.bad.al`.
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