sysbench update index performance degradation by commit e8c32a

[dbsid]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

compare the sysbench oltp_update_index on commit e8fb81b4fb316723251e2c41dd52f8795a with baseline.

2. What did you expect to see? (Required)

no performance degradation

3. What did you see instead (Required)

before

after

4. What is your TiDB version? (Required)

v6.6