Allow Date + Time = DateTime

[nihalzp]

SET use_legacy_to_time = 0;
SELECT toDate('2024-07-15') + toTime('14:30:25') AS dt, toTypeName(dt);

┌──────────────────dt─┬─toTypeName(dt)─┐
│ 2024-07-15 14:30:25 │ DateTime       │
└─────────────────────┴────────────────┘

SELECT toDate('2024-07-15') + toTime64('14:30:25.123456', 6) AS dt, toTypeName(dt);

┌─────────────────────────dt─┬─toTypeName(dt)─┐
│ 2024-07-15 14:30:25.123456 │ DateTime64(6)  │
└────────────────────────────┴────────────────┘

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):

Date and Date32 values can now be added to Time and Time64 values using the + operator, producing a DateTime or DateTime64 result. For example, SELECT toDate('2024-01-15') + toTime('14:30:25') returns 2024-01-15 14:30:25. The result is computed in the session timezone, and out-of-range results are handled according to the date_time_overflow_behavior setting. Closes #95914.

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

[clickhouse-gh]

Workflow [PR], commit [46600b2]

Summary: ✅

---

AI Review

Summary

This PR adds Date/Date32 + Time/Time64 support in plus, returning DateTime/DateTime64 with overflow behavior controlled by date_time_overflow_behavior, plus comprehensive docs and stateless coverage. Functionality and edge-case tests look strong. I found one major compile-time concern already reported inline by clickhouse-gh[bot]: a heavy include was added to a very high-fan-out header.

Findings

⚠️ Majors

• [src/Functions/FunctionBinaryArithmetic.h:53] Interpreters/Context.h was added into a hot, widely included header path. This increases transitive rebuild scope and compile time across many translation units. Keep only lightweight declarations in the header and move settings/context-dependent logic behind a .cpp boundary.

ClickHouse Rules

Item	Status	Notes
Deletion logging	➖
Serialization versioning	➖
Core-area scrutiny	✅
No test removal	✅
Experimental gate	➖
No magic constants	✅
Backward compatibility	✅
SettingsChangesHistory.cpp	➖
PR metadata quality	✅
Safe rollout	✅
Compilation time	⚠️	High-fan-out header gained heavy interpreter dependency (Interpreters/Context.h).
No large/binary files	✅

Final Verdict

• Status: ⚠️ Request changes
• Minimum required actions:
  • Remove the heavy transitive include dependency from FunctionBinaryArithmetic.h by moving context/settings-dependent implementation details out of the header.

[clickhouse-gh]

LLVM Coverage Report

Metric	Baseline	Current	Δ
Lines	84.00%	84.00%	+0.00%
Functions	90.90%	90.90%	+0.00%
Branches	76.50%	76.50%	+0.00%

Changed lines: 94.55% (208/220) · Uncovered code

Full report · Diff report

[alexey-milovidov]

Looks good! First I thought about time zones, but as neither Date or Time have them, the only option is to use the default (session) timezone for DateTime.