Note:
This topic has been translated from a Chinese forum by GPT and might contain errors.Original topic: 相同的SQL执行计划不一样是什么原因

【TiDB Usage Environment】Production Environment / Testing / PoC
【TiDB Version】
【Reproduction Path】What operations were performed when the issue occurred
【Encountered Issue: Problem Phenomenon and Impact】
【Resource Configuration】Go to TiDB Dashboard - Cluster Info - Hosts and take a screenshot of this page
【Attachments: Screenshots / Logs / Monitoring】
The same SQL has different execution plans. The sn_type field has an index, but sometimes it still performs a full table scan.
The following execution plan does not use the index.