INFORMATION_SCHEMA.CLUSTER_STATEMENTS_SUMMARY: Abnormal behavior when logging statement using primary key index

[c4pt0r]

Bug Report

If a statement uses a primary key index, the primary key index is not recorded in the IndexName column of CLUSTER_STATEMENTS_SUMMARY table

1. Minimal reproduce step (Required)

create table tt(a varchar(255) primary key);
insert into tt values("a");
select * from tt where a = "a";
select `INDEX_NAMES` from INFORMATION_SCHEMA.CLUSTER_STATEMENTS_SUMMARY where digest_text = 'select * from `tt` where `a` = ?';

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

INDEX_NAMES
----------
tt:PRIMARY

3. What did you see instead (Required)

INDEX_NAMES
----------
<null>

4. What is your TiDB version? (Required)

tidb_version() | Release Version: v6.1.0
Edition: Community
Git Commit Hash: 1a89decdb192cbdce6a7b0020d71128bc964d30f
Git Branch: heads/refs/tags/v6.1.0
UTC Build Time: 2022-06-05 05:09:33
GoVersion: go1.18.2
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false

[CbcWestwolf]

/assign