executor: replace should not change other rows when auto ID is out of range (#30301)

[ti-srebot]

cherry-pick #30301 to release-5.2
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/33863

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---

What problem does this PR solve?

Issue Number: close #29483

Problem Summary:

SET sql_mode="NO_ENGINE_SUBSTITUTION";
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a tinyint not null auto_increment primary key, b char(20));
INSERT INTO t1 VALUES (127,"maxvalue");
REPLACE INTO t1 VALUES (0,"newmaxvalue");

Specifying a zero value for the auto_increment column triggers ID allocation. In the current implementation, the allocated ID will be replaced in the row which is equivalent to

REPLACE INTO t1 VALUES (128,"newmaxvalue");

Since 128 is out of range for tinyint column, 128 is truncated to 127 in setDatumAutoIDAndCast():

REPLACE INTO t1 VALUES (127,"newmaxvalue");

However, these two REPLACE statements should be different because

• for the 0 case, it means adding a new row.
• for the 127 case, it means updating an old row if exists.

What is changed and how it works?

In this PR, I add a check inside setDatumAutoIDAndCast() to prevent a truncated auto-ID is used. The error message is different from MySQL's "duplicate primary key" because of the implementation difficulty: there is no way to tell ReplaceExec that whether the row is filled by auto-IDs without changing the interface.

tidb/executor/replace.go

Line 192 in a046014

func (e *ReplaceExec) exec(ctx context.Context, newRows [][]types.Datum) error {

This can cause MySQL incompatibility when there is no duplicated auto-ID:

SET sql_mode="";
CREATE TABLE t1 (a tinyint not null auto_increment primary key, b char(20));
INSERT INTO t1 VALUES (127,"maxvalue");
DELETE FROM t1;
REPLACE INTO t1 VALUES (0,"newmaxvalue"); -- MySQL executes successfully
-- ERROR 1467 (HY000): Failed to read auto-increment value from storage engine

I think it is fine because this error can be an alert, reminding the users that auto-IDs are exhausted.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix an issue that REPLACE statement changing other rows when the auto ID is out of range

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AilinKid
• bb7133

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[ti-srebot]

/run-all-tests

[ti-srebot]

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

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/106d665f6ac8747bc38c803007140c2e9acf38eb

[bb7133]

LGTM

[winoros]

/merge

[ti-chi-bot]

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

Commit hash: 41360e2

[winoros]

/run-mysql-test

[tangenta]

Blocked by https://github.com/pingcap/tidb-test/pull/1663

[winoros]

/run-mysql-test tidb-test=pr/1663

[winoros]

/run-mysql-test tidb-test=pr/1663

[ti-chi-bot]

@ti-srebot: Your PR was out of date, I have automatically updated it for you.

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[tangenta]

/run-mysql-test tidb-test=pr/1663