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a9f3c50863
The previous LLM-generated knowledge files contained factual
hallucinations. The most visible was the claim that `FindFirst` /
`FindLast` "forces a full-table scan" on an unfiltered record - it does
not; those APIs return a single row via the current key.
Other inaccuracies the audit found and fixed:
* `FindSet(true)` was described as "taking a LockTable". The correct
upstream phrasing is that `FindSet(true)` sets
`ReadIsolation::UpdLock` on the read. UpdLock and LockTable are
related but distinct mechanisms.
* The list of production-scale tables had been invented beyond the
upstream source (e.g. "Detailed Cust. Ledg. Entry") without a
citation. The regenerated list matches the ten tables upstream lists
with their P95 row counts.
* `SetLoadFields` guidance had been augmented with an extra mechanism
claim ("the database resolves the filter using the index without
hydrating the value") not present in upstream.
Approach: full regeneration of `microsoft/knowledge/` from the six
upstream BCApps Code Review instruction files, with Microsoft Learn /
the AL language reference as a secondary source. Every claim in every
regenerated file is anchored to a verbatim upstream quote (or a Learn
URL); the audit trail lives in artifacts/trace-<domain>.json on the
session workspace.
The PR #11 transaction/error-handling cluster is preserved verbatim:
* performance/understand-implicit-transaction-boundary.md
* performance/codeunit-run-as-atomic-sub-operation.{md,good.al,bad.al}
* performance/codeunit-run-requires-prior-commit-inside-transaction.{md,good.al,bad.al}
* performance/use-tryfunction-for-error-catching-not-rollback.{md,good.al,bad.al}
* performance/avoid-commit-inside-loops.{md,good.al,bad.al}
* security/commitbehavior-attribute-scopes-explicit-commits.{md,good.al,bad.al}
* testing/transactionmodel-attribute-governs-test-transactions.{md,good.al,bad.al}
These articles already cite Microsoft Learn and were carefully
cross-referenced; the regeneration skips their topics rather than
duplicating them.
File counts after regeneration:
performance 35 .md (5 preserved + 30 new)
privacy 17 .md
security 18 .md (1 preserved + 17 new)
style 33 .md
testing 1 .md (preserved)
ui 19 .md
upgrade 18 .md
Total 141 atomic knowledge files, each strictly one rule. All pass
.github/scripts/validate_frontmatter.py with 0 errors and 0 warnings.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
26 lines
1.4 KiB
Markdown
26 lines
1.4 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [get, findfirst, primary-key, setrange, lookup]
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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 Get when the full primary key is known; FindFirst is the wrong tool
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## Description
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`Get(...)` is the direct primary-key lookup. `FindFirst()` walks an index — even when narrowed by `SetRange` on every primary-key field. The upstream review guidance treats `Customer.SetRange("No.", CustomerNo); if Customer.FindFirst() then ...` as a bad pattern and `if Customer.Get(CustomerNo) then ...` as the correction. The two reach the same record; only `Get` expresses the lookup as a primary-key seek.
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## Best Practice
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When all primary-key fields are available at the call site, call `Get` (or `GetBySystemId`) with them. Reserve `FindFirst` for cases where the filter is on something other than the full primary key — a unique secondary field, a partial composite key, a sort that the caller cares about.
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See sample: `use-get-instead-of-findfirst-on-full-primary-key.good.al`.
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## Anti Pattern
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Composing `SetRange` calls that exactly cover the primary key and then calling `FindFirst`. The result is correct but the call site reads as "search the table" rather than "look up by key", which obscures both the intent and the access pattern from later reviewers.
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See sample: `use-get-instead-of-findfirst-on-full-primary-key.bad.al`.
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