executor: fix wrong key range of index scan when filter is comparing year column with NULL (#23079)

[ti-srebot]

cherry-pick #23079 to release-4.0
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/23104

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git push [email protected]:ti-srebot/tidb.git pr/23104:release-4.0-db62e341fd24

---

Signed-off-by: guo-shaoge [email protected]

What problem does this PR solve?

Issue Number: close #23038

Problem Summary: use following case:

use test;
drop table if exists gjttbl;
CREATE TABLE `gjttbl` (
    `gjtc1` year(4) DEFAULT NULL COMMENT 'DATE AND TIME',
    `gjtc2` varchar(20) DEFAULT NULL,
    KEY (`gjtc1`)
    );
insert into gjttbl values(1, "1");
insert into gjttbl values(1, "2");
select  t1.gjtc1, t2.gjtc1  from gjttbl as t1 inner join gjttbl as t2 on t1.gjtc1 = t2.gjtc1 where t1.gjtc1 != NULL;

Output should be empty, but TiDB give result.

What is changed and how it works?

What's Changed: change datum.go:convertToMysqlYear(), when arg is NULL, this function accidentally set result tobe zero year.

How it Works: go:convertToMysqlYear() is called by ranger.(*builder).buildFormBinOp(), which will build key range. So if go:convertToMysqlYear() change NULL to zero, the key range for index scan is wrong.

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Integration test: tidb_test.go:TestYear()

Side effects: no

Release note

• fix wrong key range of index scan when filter is comparing year column with NULL

[ti-srebot]

/run-all-tests

[ti-srebot]

@guo-shaoge you're already a collaborator in bot's repo.

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

/run-check_dev

[guo-shaoge]

Rely on this PR

[guo-shaoge]

/run-check_dev

[XuHuaiyu]

/LGTM

[AilinKid]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AilinKid
• XuHuaiyu

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[AilinKid]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: b060836

[guo-shaoge]

/run-unit-test