I'm curious of the rest of the architecture. Each benchmark needs to be tested separately, as ZFS is likely caching the reads in the ARC. We also need a benchmark of ZFS without compression enabled.
However, we're not showing how bad ext3 is, but that the end result still shows the stellar performance, compression or not.
Each of the seven queries we used in our benchmark required a sequential scan of the 32GB dataset. It's unlikely that the ARC had any impact on the results since the EC2 instance had only 7GiB of memory.
ext3 does suck for certain workloads, one of them being large scale db's. And by suck, I mean dangerous. Unless you really want to set barrier on the fs and watch your IO plummet to 45 record player speeds.
However, we're not showing how bad ext3 is, but that the end result still shows the stellar performance, compression or not.