Is it normal to use LocalDb in production?

Question

I know that using LocalDb is very good and easy for developement, I wonder if it's good idea to use it in production when I host websites on IIS server?

I'm asking because I wonder if it won't have any kind of speed issues in production.

This is my connection string that I want to use in production

Server=(LocalDB)\\v11.0;Integrated Security=SSPI;MultipleActiveResultSets=true; AttachDBFilename=|DataDirectory|ProjectDB.mdf; 

Answer 1

LocalDB is absolutely supported in production. From the performance point of view it is identical to SQL Server Express, as they share the same database engine.

Now, for a site running in full IIS I would recommend using service-based instance of SQL Server Express. Since IIS is running as a service it is best to have a service-hosted database as well. That means you should not be using User Instance=true or AttachDbFileName=... in your connection string.

If you want to learn more, I recommend this post on using LocalDB from full IIS, part 1 and its follow up, part 2. They go into more details.

Answer 2

"Normal" - hard to say, that's a relative term.

Permitted - yes. Here is a quote from the Microsoft SQL Server Express blog where LocalDB was introduced:

"...if the simplicity (and limitations) of LocalDB fit the needs of the target application environment, developers can continue using it in production, as LocalDB makes a pretty good embedded database too."

---

UPDATE (March 2019)

After using LocalDB in dozens of production sites for two solid years now, I'll confirm that it works. However, if you need a free multi-user ("shared" in LocalDB terminology) DB, use SQL Server Express instead. LocalDB is not a good multi-user solution. There are MANY obstacles to overcome. I don't have time now, but if you would like details on those obstacles and respective workarounds, leave a comment, and I'll document them here or in another question.

---

UPDATE (April 2021)

Showstopper -- the shared (i.e., multi-user) instance feature is broken in SQL Server LocalDB 2017 and 2019. Having one of those versions installed will even prevent accessing a shared instance created in an earlier version. The problem is documented here. The only known "workaround" is to uninstall the broken LocalDB versions, and use LocalDB 2016 or earlier.

---

UPDATE (September 2021)

There is now a fix for the Showstopper issue mentioned in the preceding update (UPDATE April 2021). Caveat: I have not personally tested this fix.