I'm using a sqlite db which is very convenient and seems to meet all of my needs at this point.
Currently my db size is <50MB, but I now need to add a new table which will store large text blobs, which will cause the db to reach up to 5GB within the next year.
Would sqlite be able to deal with a 5GB db size? Any caveats to that, compared with say mysql?
I'm not a huge expert on databases, but most of the DB-related work I've done used SQLite. In my experience, making the database larger in-itself shouldn't incur a large performance hit. Naturally you'll have more data, so prepare to spend more time querying it!
Consider this thought experiment: you have a table named mydata you use all the time in the DB. Now, you add an unrelated table otherdata. Your queries for mydata don't depend on the information in otherdata. Even if you shove GBs of data into otherdata, you won't feel any real performance hit in your usage of mydata.
AFAIK, the architecture of SQLite supports this claim.
SQLite should be just fine for what you want to do. Size really isn't a concern. As long as your data file can reside on the same computer that's making the call, you should be just fine. If you put it on the network, that's ok, but multi-user access is subject to the bugs of the operating system when it comes to locking records, etc. Per comparing with mysql, since you've eliminated the server, you've also eliminated the network traffic associated with the data retrieval. this should speed things up.
-don