Frontend show tables failed with table name "sys.cpu.system"

[MichaelScofield]

mysql> show tables; ERROR 1815 (HY000): Failed to execute query: show tables, source: Failed to execute query: show tables, source: General catalog error: Cannot parse catalog value, source: Invalid catalog info: __tg-greptime-public-sys.cpu.system

[v0y4g3r]

Don't think that's an issue, allowing . in table name will cause confusion, since full qualified table name already uses . as the delimiter between catalog name and schema name. MySQL does not allow table name with . too.

Maybe we should transform the prometheus table name from sys.cpu.system to sys_cpu_system in the protocol handler layer, which won't break the invariants in database layer.