Enhancement

TiDB supports the 'local temporary table'(compatible with MySQL) and 'global temporary table'(from ANSI SQL standard). However, there is no temporary table information in information_schema.tables, it's not very easy to manage them.

So we would like to add both local temporary and global temporary tables in information_schema.tables. For TABLE_TYPE column, we show LOCAL TEMPORARY for a local temporary table, GLOBAL TEMPORARY for a global temporary table

Note: this is not compatible with MySQL.

• MySQL only supports local temporary table, and they do not show local temporary table in information_schema.tables. Instead, it provides information_schema.INNODB_TEMP_TABLE_INFO.
• We think it is fine because we follow the SQL standard.