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feat: add toStartOf* date-time function translations via EF.Functions - #57
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Expose the ClickHouse toStartOf* family as EF.Functions extension methods, following the existing EF.Functions.SimpleJson* pattern. This is the provider's first date-time translation surface. Covers the full family: ToStartOfYear/Quarter/Month/Week (with optional week mode), ToStartOfDay/Hour/Minute/Second, the fixed buckets FiveMinutes/TenMinutes/FifteenMinutes, and the general ToStartOfInterval(source, value, unit). Each is generic over the source so DateTime, DateOnly, and DateTime64-mapped columns all work, including in GROUP BY. ToStartOfInterval takes a ClickHouseInterval enum unit and is emitted as toStartOfInterval(source, toInterval<unit>(value)), avoiding raw INTERVAL n UNIT syntax; the unit must be a constant to be translated. The reflection-based translator dictionary leaves room to add the rest of the ClickHouse date family (toYear, date_diff, addX, ...) with no new plumbing. The optional timezone/origin trailing args are deferred to future overloads. Note: default ToStartOfWeek mode 0 is Sunday-based, verified empirically against ClickHouse 25.8 (the upstream docs example is stale). New: - Metadata/ClickHouseInterval.cs - Extensions/ClickHouseDateTimeDbFunctionsExtensions.cs - Query/ExpressionTranslators/Internal/ClickHouseDateTimeMethodTranslator.cs - test/EFCore.ClickHouse.Tests/DateTimeFunctionsTranslationTests.cs (20 tests) Modified: - register translator in ClickHouseMethodCallTranslatorProvider - mark the extensions type non-client-evaluable in ClickHouseEvaluatableExpressionFilter - README.md, CHANGELOG.md, RELEASENOTES.md Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Pull request overview
Adds EF Core translations for ClickHouse toStartOf* date/time functions.
Changes:
- Adds public
EF.Functions.ToStartOf*APIs and interval units. - Registers translation and client-evaluation filtering.
- Adds integration tests and user documentation.
Reviewed changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.
Show a summary per file
| File | Description |
|---|---|
ClickHouseInterval.cs | Defines supported interval units. |
ClickHouseDateTimeDbFunctionsExtensions.cs | Exposes date/time functions. |
ClickHouseDateTimeMethodTranslator.cs | Generates corresponding ClickHouse SQL. |
ClickHouseMethodCallTranslatorProvider.cs | Registers the translator. |
ClickHouseEvaluatableExpressionFilter.cs | Prevents client evaluation. |
DateTimeFunctionsTranslationTests.cs | Tests translation and execution. |
README.md | Documents usage. |
CHANGELOG.md | Records the feature. |
RELEASENOTES.md | Describes the release behavior. |
Suppressed comments (1)
src/EFCore.ClickHouse/Query/ExpressionTranslators/Internal/ClickHouseDateTimeMethodTranslator.cs:163
toStartOfIntervalhas an additional server-version issue: ClickHouse's release history says source-type-preserving extended results were only fixed in 26.1, while this PR explicitly targets/tests 25.8. Mapping the result as the source type cannot prevent 25.8 from narrowingDate32/DateTime64, so extended-range buckets can be wrong. Either establish ClickHouse 26.1 as the minimum and enforce the extended-results setting, or implement semantics compatible with the supported server range.
returnType: method.ReturnType,
typeMapping: source.TypeMapping);
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tomh4
commented
Aug 11, 2026
ContributorAuthor
i will revisit this to make the bots happy |
EF.Functions.ToStartOf* with a constant argument is a client-eval candidate; ClickHouseEvaluatableExpressionFilter forces it server-side. No existing test exercised that path (all pass columns), so it showed as uncovered. Add a translation-only test that asserts the constant-argument call is emitted as server-side SQL.
The notes claimed the whole family works over DateOnly. Verified against ClickHouse 23.8, 24.8 and 26.7: the calendar and sub-day truncation functions accept Date32, but toStartOfInterval rejects it on older releases (Illegal type Date32). Also drop the incorrect claim that toStartOfSecond requires DateTime64 (it accepts Date/DateTime and returns DateTime64). Split the statement by function and input type.
The 2026-only test couldn't catch ClickHouse's default narrowing of Date/DateTime results. Add pre-1970 integration cases showing the calendar clamp (1920 -> 1970) and the interval wraparound, plus a case that enables enable_extended_results_for_datetime_functions (via a set_* connection string) and verifies Date32/DateTime64 preserve the full range. Document the range limitation and the opt-in in README/CHANGELOG/RELEASENOTES.
alex-clickhouse
commented
Aug 12, 2026
Collaborator
LGTM, thank you for the PR! |
alex-clickhouse
approved these changes
Aug 12, 2026
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Addresses issue Feature Request: Add Support for toStartOf* #56 , created in a similar way to exisiting Functions Extensions (e.g. ClickHouseJsonDbFunctionsExtensions)
Once there is support for DateTimeOffset, this might need to be revised adn adjusted (see DateTimeOffset not supported #53)
Expose the ClickHouse toStartOf* family as EF.Functions extension methods, following the existing EF.Functions.SimpleJson* pattern.
Covers the full family: ToStartOfYear/Quarter/Month/Week (with optional week mode), ToStartOfDay/Hour/Minute/Second, the fixed buckets FiveMinutes/TenMinutes/FifteenMinutes, and the general ToStartOfInterval(source, value, unit). Each is generic over the source so DateTime, DateOnly, and DateTime64-mapped columns all work, including in GROUP BY.
ToStartOfInterval takes a ClickHouseInterval enum unit and is emitted as toStartOfInterval(source, toInterval(value)), avoiding raw INTERVAL n UNIT syntax; the unit must be a constant to be translated.
Adding the rest of the ClickHouse date functions later (toYear, date_diff, addX, and so on) can be easily don. I left off the optional timezone/origin arguments for now; we can add overloads for those if anyone needs them.
IMPORTANT: ToStartOfWeek with the default mode (0) starts weeks on Sunday, not Monday. I checked this against ClickHouse 25.8 directly because the example in their docs actually shows the wrong output.. (https://clickhouse.com/docs/reference/functions/regular-functions/date-time-functions#toStartOfWeek)
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