RavenDB Performance Tweaks

time to read 2 min | 298 words

Continuing my efforts to make RavenDB faster, I finally settled on loading all the users from Stack Overflow into Raven as a good small benchmark for Raven. This is important, because I want something big enough to give me meaningful stats, but small enough so I would have to wait too long for results.

The users data from Stack Overflow is ~180,000 documents, but it loads in just a few minutes, so that is very useful.

With that, I was able to identify a major bottleneck:


The AddTask takes a lot of time, mostly because it needs to update a Json field, so it needs to load it, update, and then save it back. In many cases, it is the same value that we keep parsing over & over again. I introduced a Json Cache, which could save the parsing cost. When introducing this, I was also able to make it useful in a few other places, which should hopefully improve performance in a few more places.

Current speed, when inserting ~183,000 documents (over HTTP on the local host) in batches of 128 documents is 128 milliseconds. I consider this pretty good. Note that this is with indexing enabled, but not counting how long it takes for the background indexes to finish processing.

When measuring that as well, after inserting hundreds of thousands of documents, it took another half a second (but note that my measuring granularity was 0.5 second) to finish updating the indexes on the background. I think it is time to try to throw the entire StackOverflow data dump at Raven and see how fast it can handle it.