Fix delta external table schema diff, script syntax, and cleanup#164
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ashleyvansp merged 3 commits intomainfrom Apr 13, 2026
Merged
Fix delta external table schema diff, script syntax, and cleanup#164ashleyvansp merged 3 commits intomainfrom
ashleyvansp merged 3 commits intomainfrom
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Three fixes for delta external tables: 1. Schema perpetual diff: The bulk loader populates the schema for all external tables from the cluster, but delta tables auto-infer their schema from the delta log — so YAML configs intentionally omit it. This caused a perpetual diff on every run. Fix: before comparing, clear the cluster-side schema for delta tables when the YAML doesn't specify one. If the YAML provides a custom schema, keep it for proper comparison. 2. Missing closing paren: CreateDeltaScript generated an unclosed parenthesis around the connection string, producing invalid KQL that fails Kusto syntax validation and cannot be applied. 3. Remove unnecessary dataFormat requirement: Delta tables don't use dataformat= in the Kusto command syntax. Removed the misleading validation that required it. 4. Only emit with() properties when set: Delta script no longer emits empty folder='', docString='', fileExtension='' when not specified in YAML. The with() block is omitted entirely if no properties are set. Fixes github/data#11973 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
Fixes delta external table generation and diffing so YAML configs can intentionally omit schema without causing perpetual diffs, and corrects delta script syntax/output.
Changes:
- Adjust delta external table script generation (fix connection-string parenthesis; emit
with(...)only when properties are set; removeDataFormatrequirement). - Suppress perpetual schema diffs for delta external tables by clearing cluster-side schema when YAML omits schema.
Show a summary per file
| File | Description |
|---|---|
| KustoSchemaTools/Model/ExternalTable.cs | Updates delta external table KQL script emission (syntax + conditional with() properties). |
| KustoSchemaTools/Changes/DatabaseChanges.cs | Adds delta-specific schema normalization to avoid phantom/perpetual diffs during comparison. |
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whitleykeith
approved these changes
Apr 13, 2026
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Fixes for delta external tables:
dataformat=in the Kusto command syntax.with()properties when set; Delta script no longer emits emptyfolder='', docString='', fileExtension=''when not specified in YAML.Fixes github/data#11973