Querying stats_extended reports syntax error

[djshow832]

Bug Report

Selecting stats_extended reports syntax error, and I have to add quotes for it:

select * from `stats_extended`;

Is stats_extended implemented as a keyword in show stats_extended? It doesn't make sense because other stats tables are fine, such as select * from stats_histograms.

1. Minimal reproduce step (Required)

select * from stats_extended limit 1;

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

It outputs something.

3. What did you see instead (Required)

mysql> select * from stats_extended limit 1\G
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 28 near "stats_extended limit 1"

4. What is your TiDB version? (Required)

master

[eurekaka]

This is because stats_extended is marked as a reserved keyword now, while stats_histograms is marked as tidb keyword. The rationale behind this difference is to support the syntax like alter table t add stats_extended s1 ..., if stats_extended is not marked as a reserved keyword, the parser cannot know it is a keyword or a column name, since alter table t add [column] a ... is supported as well.