Filter stat for ReferenceSearchParam and UriSearchParam table

[apurvabhaleMS]

Description

This PR extends the SQL Server filtered statistics mechanism to cover ReferenceSearchParam and UriSearchParam tables, which were previously missing. When FHIR searches hit these tables, the query optimizer now has per-resource-type statistics for better plan selection.

dbo.ReferenceSearchParam

• ST_ReferenceResourceId_WHERE_ResourceTypeId_40_SearchParamId_1219 — stat on the ReferenceResourceId
• ST_ReferenceResourceTypeId_WHERE_ResourceTypeId_40_SearchParamId_414 — stat on the ReferenceResourceTypeId

dbo.UriSearchParam

• ST_Uri_WHERE_ResourceTypeId_144_SearchParamId_1219 — stat on the Uri

Screenshots

Related issues

Addresses AB189018.

Testing

Describe how this change was tested.

FHIR Team Checklist

• Update the title of the PR to be succinct and less than 65 characters
• Add a milestone to the PR for the sprint that it is merged (i.e. add S47)
• Tag the PR with the type of update: Bug, Build, Dependencies, Enhancement, New-Feature or Documentation
• Tag the PR with Open source, Azure API for FHIR (CosmosDB or common code) or Azure Healthcare APIs (SQL or common code) to specify where this change is intended to be released.
• Tag the PR with Schema Version backward compatible or Schema Version backward incompatible or Schema Version unchanged if this adds or updates Sql script which is/is not backward compatible with the code.
• When changing or adding behavior, if your code modifies the system design or changes design assumptions, please create and include an ADR.
• CI is green before merge
• Review squash-merge requirements

Semver Change (docs)

Patch|Skip|Feature|Breaking (reason)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@816452f). Learn more about missing BASE report.

Additional details and impacted files

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[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds filtered-statistics support for additional SQL search parameter tables (ReferenceSearchParam and UriSearchParam) and verifies the behavior with new unit/integration tests.

Changes:

• Extend GetKeyColumns to include dbo.ReferenceSearchParam and dbo.UriSearchParam key columns.
• Add unit tests covering GetKeyColumns across single/two-column tables and unknown/null tables.
• Add integration tests asserting filtered stats are created (and skipped for :missing / NotExists expressions).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
test/Microsoft.Health.Fhir.Shared.Tests.Integration/Persistence/SqlServerCreateStatsTests.cs	Adds integration coverage for stats creation for Reference/Uri params and for NotExists behavior.
src/Microsoft.Health.Fhir.SqlServer/Features/Search/SqlServerSearchService.cs	Expands key-column mapping for filtered stats to Reference/Uri tables and shares it with the stats pipeline.
src/Microsoft.Health.Fhir.SqlServer.UnitTests/Features/Search/SqlServerSearchServiceTests.cs	Adds unit tests validating the expanded GetKeyColumns behavior.

[SergeyGaluzo]

I think stats on ref search param should be ST_ReferenceResourceId_WHERE_ResourceTypeId_40_SearchParamId_1219_ReferenceResourceTypeId_XXX