We don’t support the use of MySQL variables within a statement. Thus using @tot will force execution by the MySQL query engine, which negates the benefits you get from the Knowledge Grid. You can disable the MySQL Query Path in the latest releases of Infobright which will save you having to wait, and ultimately abort the query.

Hope this helps,
Mark

This blog post is not about EXPLAIN in infobright … but about the fact that a query which on mysql takes ages, on infobright takes very little time (awesome):
mysql> SELECT COUNT(ac.UID) FROM ACTIVE ac JOIN ALL a ON ac.UID=a.UID;
+—————+
| COUNT(ac.UID) |
+—————+
| 17466 |
+—————+
1 row IN SET (0.23 sec)

but when setting a variable to the result:
mysql> SET @tot = (SELECT COUNT(ac.UID) FROM ACTIVE ac JOIN ALL a ON ac.UID=a.UID);

^CQuery aborted BY Ctrl+C

the variable setting fails because it takes too long, implying that running the query went through the IB optimiser but setting a variable tot equal to the result went through the mysql optimiser thus taking ages.

Regards,
Darren

Infobright doesn’t support EXPLAIN – hence the extra processing time via the MySQL Query Path. We’ve got a fair amount documented about this within our forums and Wiki. Here’s a link to the Wiki specifically about this topic with information about turning on the query execution log. Feel free to stop by the forums – we’re very prompt with our responses!

http://www.infobright.org/wiki/Query_Execution_Log/

Regards,
Mark Windrim
VP Community Relations @ Infobright