What problem does this PR solve?

Issue Number: close #982

Problem Summary: before this PR, auto_increment ID and _tidb_rowid share the same key-value. The problem is any action that affects auto_increment column also has an impact on _tidb_rowid. For example,

create table t (a bigint auto_increment unique key);
insert into t values (9223372036854775805); -- MaxInt64-2
insert into t values (1);

Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
ERROR 1467 (HY000): Failed to read auto-increment value from storage engine

The first insert statement forces auto_increment ID rebase to 9223372036854775807. Even if the second insert statement does not trigger auto_increment ID allocation, TiDB throws an "Failed to read" error because the _tidb_rowid allocator is exhausted.

What is changed and how it works?

Proposal: xxx

What's Changed:

How it Works:

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

Please add a release note, or a 'None' if it is not needed.