Bug #30850 federated engine cause an query error when disconnect
Submitted: 6 Sep 2007 2:14 Modified: 6 Sep 2007 8:49
Reporter: ming lu Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server: Federated storage engine Severity:S2 (Serious)
Version:5.1.20 OS:Any
Assigned to: CPU Architecture:Any

[6 Sep 2007 2:14] ming lu
Description:
Create some federated engine tables, when anyone of these tables disconnect with the remote MySQL database, a SQL query against to the information_schema.tables will occur error.

The error message: 
   There was a problem processing the query on the foreign data source. Data source error: %The foreign data source you are trying to reference does not exist. Data source error:  : 2003 : Can't connect to MySQL server on '192.168.1.113' (10061)

I think the mechanism like this is not a good idea, any federated table's error(for example, the network's fault) will cause the access failure against to information_schema.tables. 

How to repeat:
see the Description
[6 Sep 2007 8:49] Sveta Smirnova
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://dev.mysql.com/doc/ and the instructions on
how to report a bug at http://bugs.mysql.com/how-to-report.php

Not every query to information_schema.tables fails with error in described case, but only queries which involve federated table. For example, query SELECT * FROM information_schema.tables WHERE table_name='myisam_table'; will success.

But because information_schema.tables contains information about row count, it should access to the underlying table. So I'll close the report as "Not a Bug"