32c40bbf1d
Converts an existing performance-review prompt into 22 atomic knowledge articles under microsoft/knowledge/performance/, each paired with AL samples under samples/performance/<slug>/ demonstrating the anti-pattern and/or the best practice. The full set seeds the corpus the microsoft/skills/al-performance-review leaf skill matches against and validates the READ knowledge-file format end-to-end. Every article conforms to the READ contract: six required frontmatter fields, Description always present, no fenced code blocks, sample code referenced by repo-relative path. Each article is marked with a blockquote 'Seed article' note so domain stewards can extend or restructure them freely. Articles (ordered by concern area): Database query efficiency - use-findset-with-next (AA0181) - avoid-findfirst-with-next (AA0233) - only-fetch-records-you-use (AA0175) - use-findset-readonly-by-default - use-setloadfields-for-partial-records - use-addloadfields-in-report-layouts - use-calcsums-to-aggregate-filtered-sets (file: use-calcsums-for-flowfield-totals.md) - avoid-calcfields-in-loops - add-sift-keys-for-flowfields (AA0232) - use-isempty-for-existence-checks Filter and key optimization - filter-before-find - set-current-key-to-match-filters Temporary tables and transactions - use-temporary-tables-for-intermediate-data - keep-transaction-scope-short - avoid-user-interaction-in-transactions - avoid-commit-inside-loops Record operations - prefer-get-for-primary-key-lookups - use-insert-false-when-skipping-triggers - prefer-direct-record-over-recordref Strings, codeunits, events - use-strsubstno-for-message-formatting - use-single-instance-codeunits-for-caching - keep-event-subscribers-lightweight samples/README.md documents the sample-folder convention and makes clear the samples are demonstration-only, not derived from BC base application source, with unique object IDs in the 50100-50199 range. Rubber-duck pass caught: a misleading good.al in avoid-calcfields-in-loops (fixed by switching to a hoistable CalcFields scenario), an invalid event subscriber signature in keep-event-subscribers-lightweight (fixed by adding var xRec), normative guidance leaked into the Description of use-findset-readonly-by-default (moved to Anti Pattern), a missing sample pair for keep-transaction-scope-short (added), and muddy FlowField/CalcSums framing (retitled and clarified). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Use IsEmpty for existence checks
Seed article. Converted from an existing performance-review prompt to bootstrap the BCQuality performance corpus. Domain stewards should expand, restructure, and refine as needed.
Description
IsEmpty is the cheapest way to answer whether at least one row matches the current filters. It short-circuits at the first match and never hydrates a record. Count() scans and counts the entire set; FindFirst fetches a full row just to be discarded.
Best Practice
Use if not Rec.IsEmpty() then ... for existence checks. Reserve Count for cases where the exact number of rows is needed, and FindFirst for cases where you actually want the row's field values.
See sample: samples/performance/use-isempty-for-existence-checks/good.al.
Anti Pattern
if Rec.Count() > 0 iterates the whole set just to answer a yes/no question. if Rec.FindFirst() then loads an entire row of data the caller never reads.
See sample: samples/performance/use-isempty-for-existence-checks/bad.al.