Query against INFORMATION_SCHEMA.TABLES degrades as the number of views increases

Queries against INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.VIEWS slow down as the number of views increases.

BI tools like Tableau issue a query like the following at connection time:

select TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE from INFORMATION_SCHEMA.`TABLES` WHERE TABLE_CATALOG LIKE 'DRILL' ESCAPE '\' AND TABLE_SCHEMA <> 'sys' AND TABLE_SCHEMA <> 'INFORMATION_SCHEMA'ORDER BY TABLE_TYPE, TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME

The time to query the information schema tables degrades as the number of views increases. On a test system:

This can result in a single connection taking more than a minute to establish.

The problem occurs because we read the view file for every view and this appears to take most of the time.

Querying information_schema.tables does not, in fact, need to open the view file at all, it merely needs to get a listing of the view files. Eliminating the view file read will speed up the query tremendously.