When creating graphs and inneficient query is causing long creation times

[cigamit]

Describe the bug
On a very large system, when you create graphs with the latest cacti, long delays take place to create those graphs.

To Reproduce
Steps to reproduce the behavior:

1. Have large system with thousands of device and hundreds of thousands of graphs
2. Attempt to create new graphs
3. Notice the performance problem

Expected behavior
Cacti should scale better at very large sizes.