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Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules. Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
30 lines
1.8 KiB
Markdown
30 lines
1.8 KiB
Markdown
---
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bc-version: [21..]
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domain: upgrade
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keywords: [datatransfer, large-dataset, bulk-update, modifyall, copyfields, new-field]
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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 `DataTransfer` for bulk updates on large tables
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## Description
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Tables that can contain more than 300,000 records, and any newly added field on an existing table, should be initialized with `DataTransfer` rather than a `repeat ... Modify ... until Next() = 0` loop. `DataTransfer` issues a single set-based statement to the database; the loop/modify pattern issues one round-trip per row and accumulates write locks for the duration of the upgrade. On the volumes that drive upgrade pain — ledger entries, item ledger entries, price list lines — the difference is the upgrade running for minutes instead of hours.
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## Best Practice
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For a bulk update use a `DataTransfer` variable: call `SetTables(Database::"...", Database::"...")` (source and destination may be the same table), add filters with `AddSourceFilter`, set the target value with `AddConstantValue` (or copy a source field with `AddFieldValue`), and execute with `CopyFields()`. To express multiple distinct updates against the same table, `Clear` the `DataTransfer` between executions and configure the next one.
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See sample: [`datatransfer-for-bulk-init.good.al`](datatransfer-for-bulk-init.good.al).
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## Anti Pattern
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Iterating with `FindSet(true) ... repeat ... Modify() ... until Next() = 0` to set a single field across an entire large table. On 300k+ rows this is the canonical slow-upgrade footgun.
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See sample: [`datatransfer-for-bulk-init.bad.al`](datatransfer-for-bulk-init.bad.al).
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## See also
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- `datatransfer-skips-triggers-and-subscribers.md` — `DataTransfer` does not raise field validation triggers or event subscribers; if a row needs validation logic, `DataTransfer` is the wrong tool.
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