bcquality/microsoft/knowledge/performance/avoid-commit-inside-loops.md
Jesper Schulz-Wedde 0e06485027
Correct performance knowledge guidance (#94)
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 667c64a8-eb36-4440-bc41-6a97d8fb5542

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
2026-07-14 11:26:29 +02:00

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---
bc-version: [all]
domain: performance
keywords: [commit, loop, transaction, lock, checkpoint, codeunit-run]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Do not Commit inside loops
> Contributions welcome — open a PR to refine or extend this article.
## Description
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.
## Best Practice
If the batch is large enough that a single transaction is untenable, use an outer loop that selects and finishes the next N rows. Commit only after the inner row loop has returned and the checkpoint state identifies where the next chunk starts. A `Codeunit.Run` boundary can also own a chunk when its implicit commit and error behavior fit the caller — see `codeunit-run-as-atomic-sub-operation.md`.
See sample: `avoid-commit-inside-loops.good.al`.
## Anti Pattern
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.
See sample: `avoid-commit-inside-loops.bad.al`.