memcachedb: All content tagged as memcachedb in NoSQL databases and polyglot persistence
And then there is another software that is really handy MemcacheDB, which is like memcached but is persistent. […] It’s very very fast, super-handy, we store far more data in MemcacheDB than we do in Postgres
Lesson learned: take such pieces of advise with a grain of salt and always test your scenario.
- It looks like Steve was not working at Reddit anymore at the time the presentation was made and so he might not have been aware of the problems related to MemcacheDB. (↩)
I read that Reddit guys are using Memcachedb and its bursting blocking writes behavior was causing them a lot of problems lately .
Memcachedb is Memcached with a built-in permanent storage system using BDB. One of the “features” of this system is that it saves up its disk writes and then bursts them to the disk. Unfortunately, the single EBS volumes they were on could not handle these bursting writes. Memcachedb also has another feature that blocks all reads while it writes to the disk. These two things together would cause the site to go down for about 30 seconds every hour or so lately.
I’d really love to hear how other NoSQL solutions are behaving in this particular scenario. Based on the characteristics of Memcachedb, I’m looking for an answer at least from the key-value stores: Project Voldemort, Redis, SimpleDB, Tokyo Cabinet, M/DB, etc. But if others want to jump in and present their solution that would be great. You can either post your reply as a comment or send it over an emai and I’ll make sure it will get included here. Thanks!
Update: I already got answers from Redis and Terrastore (document store).
Update: CouchDB and Tokyo Cabinet (note it is a bit too generic) answers are in. Still a couple are missing so please keep them coming!
Update: FleetDB (note: a data store that I haven’t covered yet, but I can promise you it is coming) has posted details about its behavior. I have also received some hints about Project Voldemort behavior but it looks like I’ll have to dig a bit deeper myself (I’ll do the same for Tokyo Cabinet). I am still awaiting comments from Riak and MongoDB. At least until now, nobody I know from Cassandra and HBase has offered to comment.