planner: fix panic when the join key is scalarFunction (#30002)

[ti-srebot]

cherry-pick #30002 to release-5.1
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/30775

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---

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

Issue Number: close #29401

Problem Summary:

If one side of the join key is string, and the another is json, the expression of the string would be cast to json and marked ParseToJSONFlag which will let WrapWithCastAsJSON wrap extra cast function.

In order to avoid this problem, we remove ParseToJSONFlag temporary during updateEQCond.

The final explain info result for the original issue is like following:

mysql> explain select /*+ inl_hash_join(t1) */ * from t t1 join t t2 on t1.b=t2.e;
+-----------------------------+----------+-----------+---------------+---------------------------------------------------------------------------------------------------------------+
| id                          | estRows  | task      | access object | operator info                                                                                                 |
+-----------------------------+----------+-----------+---------------+---------------------------------------------------------------------------------------------------------------+
| HashJoin_8                  | 12500.00 | root      |               | inner join, equal:[eq(Column#15, test.t.e)]                                                                   |
| ├─TableReader_14(Build)     | 10000.00 | root      |               | data:TableFullScan_13                                                                                         |
| │ └─TableFullScan_13        | 10000.00 | cop[tikv] | table:t2      | keep order:false, stats:pseudo                                                                                |
| └─Projection_10(Probe)      | 10000.00 | root      |               | test.t.id, test.t.a, test.t.b, test.t.c, test.t.d, test.t.e, test.t.f, cast(test.t.b, json BINARY)->Column#15 |
|   └─TableReader_12          | 10000.00 | root      |               | data:TableFullScan_11                                                                                         |
|     └─TableFullScan_11      | 10000.00 | cop[tikv] | table:t1      | keep order:false, stats:pseudo                                                                                |
+-----------------------------+----------+-----------+---------------+---------------------------------------------------------------------------------------------------------------+
6 rows in set, 1 warning (0.00 sec)

What is changed and how it works?

This request fixs this case.

Check List

Tests

• Unit test

Release note

Fix the bug that sql got cancel if including json column joins char column.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• Yisaer

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[ti-srebot]

/run-all-tests

[ti-srebot]

@Yisaer you're already a collaborator in bot's repo.

[Yisaer]

/merge

[ti-chi-bot]

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

Commit hash: 8a45a60

[Yisaer]

/merge

[ti-chi-bot]

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

Commit hash: bdd7516

[Yisaer]

/merge

[ti-chi-bot]

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

Commit hash: 95ff4a9

[Yisaer]

/merge

[ti-chi-bot]

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

Commit hash: 57391ff

[Yisaer]

/run-mysql-test

[Yisaer]

/run-all-tests