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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>
32 lines
1.9 KiB
Markdown
32 lines
1.9 KiB
Markdown
---
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bc-version: [all]
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domain: upgrade
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keywords: [initvalue, new-field, existing-rows, default-value, table-extension]
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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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# `InitValue` does not back-fill existing rows
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## Description
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`InitValue` on a field defines the value the platform assigns when a *new* record is inserted. It does not touch rows that already exist when the field is added. When a new field is added to an existing table — directly or via a table extension — every pre-existing row receives the datatype default (`false` for Boolean, `0` for numeric, empty for text), not the `InitValue`. If the intended semantics require existing rows to carry the `InitValue`, the change is incomplete without an upgrade routine that sets the field on those rows.
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Several legitimate cases do NOT need upgrade code:
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- New fields on brand-new tables (no existing rows).
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- New `Boolean` fields without `InitValue` where the datatype default `false` is the intended value.
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- New fields on configuration / setup tables that have no meaningful "existing data".
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- Informational or optional fields (logging, preferences, tracking) where `false` / empty is a valid state.
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## Best Practice
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When a new field on an existing table has an `InitValue` that matters, ship an upgrade procedure that walks the existing rows and sets the field to the same value — typically via `DataTransfer.AddConstantValue` for performance — guarded by an upgrade tag.
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See sample: `initvalue-does-not-update-existing-rows.good.al`.
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## Anti Pattern
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Adding a field with `InitValue = true;` (or any non-default `InitValue`) and shipping no upgrade code. Existing rows silently carry the datatype default, leaving the table in two states: rows created before the upgrade with the wrong value, and rows created after with the right one.
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See sample: `initvalue-does-not-update-existing-rows.bad.al`.
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