Question

I’m evaluating MongoDB, coming from Membased/memcached because I want more flexibility.

Of course Membase is excellent in doing fast (multi)-key lookups.

I like the additional options that MongoDB gives me, but is it also fast in doing multi-key lookups? I’ve seen the $or and $in operator and I’m sure I can model it with that. I just want to know if it’s performant (in the same league) as Membase.

use-case, e.g., Lucene/Solr returns 20 product-ids. Lookup these product-ids in Couchdb to return docs/ appropriate fields.

Thanks,
Geert-Jan

Answer 1

For your use case, I’d say it is, from my experience: I hacked some analytics into a database of mine that made a lot of $in queries with thousands of ids and it worked fine (it was a hack). To my surprise, it worked rather well, in the lower millisecond area.

Of course, it’s hard to compare this, and -as usual- theory is a bad companion when it comes to performance. I guess the best way to figure it out is to migrate some test data and send some queries to the system.

Use MongoDB’s excellent built-in profiler, use $explain, keep the one index per query rule in mind, take a look at the logs, keep an eye on mongostat, and do some benchmarks. This shouldn’t take too long and give you a definite and affirmative answer. If your queries turn out slow, people here and on the news group probably have some ideas how to improve the exact query, or the indexation.