You experience that nothing happens when you are clicking the + sign left to a Database Icon in the SQLyog Object Browser when connected to a MySQL version 5.x database server.

MySQL has confirmed an issue with the MySQL version 5 INFORMATION_SCHEMA, that makes queries to the INFORMATION_SCHEMA very slow if there are 'too many' objects (databases, tables, columns etc.) on the server. It is described here.

Between versions 5.0 and 5.21 SQLyog did query INFORMATION_SCHEMA when you were clicking the + sign with MySQL version 5. This was in order to be able to distinguish between TABLEs and VIEWs, what the traditional MySQL command 'Show tables..' does not.

However starting now we mostly use variations of the SHOW and SHOW status commands, as they are generally faster - also after MySQL claimed the INFORMATION_SCHEMA issue to be solved. Only when showing TRIGGERS we still need to query INFORMATION_SCHEMA, as the 'SHOW TRIGGER STATUS' command demands that user has the SUPER privilege.