Fix wrong date data type inference in case of overflow after timezone adjustment

[Avogar]

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

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

Fix wrong date data type inference in case of overflow after timezone adjustment. Closes #102601

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

[clickhouse-gh]

Workflow [PR], commit [ebe9141]

Summary: ❌

job_name	test_name	status	info	comment
Integration tests (amd_asan_ubsan, db disk, old analyzer, 5/6)		failure
	test_backup_restore_on_cluster/test_cancel_backup.py::test_short_disconnection_doesnt_stop_restore	FAIL	cidb, issue	ISSUE CREATED

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AI Review

Summary

This PR fixes parseDateTimeBestEffortImpl so DateTime inference correctly rejects values that become out of UInt32 range after timezone adjustment, then falls back to DateTime64 inference. The added stateless test covers both upper/lower boundary overflows and in-range controls. High-level verdict: the fix is targeted, aligns with the reported bug, and does not introduce obvious correctness, safety, or performance regressions.

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	✅
No large/binary files	✅

Final Verdict

• Status: ✅ Approve

[clickhouse-gh]

LLVM Coverage Report

Metric	Baseline	Current	Δ
Lines	84.10%	84.00%	-0.10%
Functions	90.90%	90.90%	+0.00%
Branches	76.60%	76.60%	+0.00%

Changed lines: 100.00% (4/4) | lost baseline coverage: 5 line(s) · Uncovered code

Full report · Diff report

[clickgapai]

Hi — this PR may need backporting to 26.3 (LTS), 26.2, 26.1, 25.8 (LTS), but no backport label was found.

Affected code: parseDateTimeBestEffortImpl post-timezone-adjustment range check in parseDateTimeBestEffort.cpp — core code present in all supported branches.

Why: The bug was introduced by commit 0bb076a ('Improve schema inference of date times', 2024-08-15), which added the strict parsing path with the pre-adjustment range check but no post-adjustment check. This commit was also backported to 24.8, so the bug predates all currently supported branches. The fix prevents wrong type inference (DateTime instead of DateTime64) and wrong values (wrap-around) for datetime strings near epoch boundaries with timezone offsets.

If this should be backported, consider adding pr-must-backport or a version-specific label (e.g. v26.3-must-backport). Ignore this if backporting is not applicable.