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* Add BC performance knowledge from OptimAL learnings Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> * Address review feedback on performance guidance Clarify predicate-supporting keys versus covering queries, demonstrate proven cache reuse, and evaluate the updated partial-load and bulk-update rules. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> --------- Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
26 lines
1.8 KiB
Markdown
26 lines
1.8 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [setautocalcfields, calcfields, calcsums, flowfield, loop, per-row]
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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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# Use SetAutoCalcFields when each iterated row needs a FlowField
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## Description
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`Record.SetAutoCalcFields` has been available since runtime 1.0 and makes the specified FlowFields calculate as records are retrieved. Microsoft's [AL database-method performance guidance](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/administration/optimize-sql-al-database-methods-and-performance-on-server#setautocalcfields) uses it to remove an explicit `CalcFields` call from every iteration when each row's FlowField drives a branch. This is different from `CalcSums`, which returns a total for the filtered set rather than a value for each row.
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## Best Practice
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Call `SetAutoCalcFields` before `FindSet` when every returned row needs the same FlowField for a comparison, branch, or per-record action. For one total of a **stored source field**, consider `CalcSums` instead (see [stored-field totals versus FlowFields](calcsums-instead-of-calcfields-in-loop.md)). If the required result is a total of selected FlowField values, derive the underlying source filters from `CalcFormula`; do not sum the FlowField directly with `CalcSums`.
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See sample: [`use-setautocalcfields-for-per-row-flowfields.good.al`](use-setautocalcfields-for-per-row-flowfields.good.al).
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## Anti Pattern
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Calling `CalcFields` inside the loop when every iteration reads the same FlowField. A compatible recent result can be cached, so do not equate each call with a SQL statement. Do not replace row-specific decisions with `CalcSums`; an aggregate cannot preserve which rows met the condition.
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See sample: [`use-setautocalcfields-for-per-row-flowfields.bad.al`](use-setautocalcfields-for-per-row-flowfields.bad.al).
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