FTA: This means in order to find what you want, you need to explore the data: you need to search it. The only tool most of us can use is grep

Um... what? Have the authors gotten stuck in a time vortex and been dropped off before, y'know, awk? Much less perl, or any of those new-fangled toys.

I mean: writing scripts to do log analysis is a pretty fundamental problem for server-side development, and lots of very smart people have spend the last two^H^H^Hthree decades working on tools to address the issue.

I don't even see how this (indexing the entries across a Hadoop cluster) is all that useful. In general, you don't do log analysis by asking "give me all the entries that match this pattern", you do it by walking them in order and extracting one or two fields from each line and building some kind of result data structure. This thing would be fine if you were asking for all the logs messages that mentioned "coffee", I guess. But what if you wanted a histogram of hit counts per page per day-of-week?