Implementing Splunk - Second Edition

When to use a summary index

When the question you want to answer requires looking at all or most events for a given source type, the number of events can become huge very quickly. This is what is generally referred to as a dense search.

For example, if you want to know how many page views happened on your website, the query to answer this question must inspect every event. Since each query uses a processor, we are essentially timing how fast our disk can retrieve the raw data and how fast a single processor can decompress that data. Doing a little math, we get the following:

1,000,000 hits per day /

10,000 events processed per second =

100 seconds

If we use multiple indexers or possibly buy much faster disks, we can cut this time but only linearly. ...