UCP: add explain for MetricSummaryTableExtractor

[crazycs520]

Description

This is a sub-task of https://github.com/pingcap/tidb/issues/15378.

What need todo? Implement the explainInfo metheod of below extractor.

• [ ] MetricSummaryTableExtractor

here is an example:

 >desc select * from `METRICS_SUMMARY` where metrics_name = "tidb_qps";
+----------------+----------+------+-----------------------+---------------+
| id             | estRows  | task | access object         | operator info |
+----------------+----------+------+-----------------------+---------------+
| MemTableScan_5 | 10000.00 | root | table:METRICS_SUMMARY |      xxx      |
+----------------+----------+------+-----------------------+---------------+

Score

• 50 score.

Mentor(s)

• @crazycs

Contact the mentors: #tidb-challenge-program channel in TiDB Community Slack Workspace

Recommended Skills

• go

Learning Materials

• Chinese: TiDB 精选技术讲解文章
• English: Awesome-Database-Learning

[jianyilyu]

/assign