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>
1.6 KiB
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Avoid RecordRef / FieldRef in hot loops when a typed record fits
Description
RecordRef and FieldRef are slower than direct typed record access — the platform resolves the table and field at runtime instead of at compile time. The trade-off is intentional: per the upstream guidance, "RecordRef/FieldRef operations are slower than direct record access, but many features REQUIRE them for generic metadata iteration (permission checks, field copying, dynamic field access)." The rule, then, is not "never use them" but "only flag when used inside a clearly unbounded hot loop (10k+ iterations) where a typed alternative exists."
Best Practice
Use RecordRef/FieldRef for genuinely generic code — permission checks, field copying, table-agnostic export. When the loop target is known at compile time and the loop iterates a large number of rows, declare the typed record and access fields directly; the saved per-iteration overhead is measurable at the volumes the rule targets.
See sample: avoid-recordref-in-hot-loop.good.al.
Anti Pattern
RecRef.Open(Database::Customer); if RecRef.FindSet() then repeat FldRef := RecRef.Field(Customer.FieldNo(Name)); ProcessName(FldRef.Value); until RecRef.Next() = 0; — the table is fixed at compile time, the field is fixed at compile time, and the loop pays the dynamic-resolution cost on every iteration. The direct Customer.Name form does the same work without the lookup.
See sample: avoid-recordref-in-hot-loop.bad.al.