Performance-wise, is it worth it to rename every mongo key name for production? [duplicate]

Question

As far as I know, every key name is stored "as-is" in the mongo database. It means that a field "name" will be stored using the 4 letters everywhere it is used.

Would it be wise, if I want my app to be ready to store a large amount of data, to rename every key in my mongo documents? For instance, "name" would become "n" and "description" would become "d".

I expect it to reduce significantly the space used by the database as well as reducing the amount of data sent to client (not to mention that it kinda uglify the mongo documents content). Am I right?

If I undertake the rename of every key in my code (no need to rename the existing data, I can rebuild it from scratch), is there a good practice or any additional advise I should know?

Answer 1

Note: this is mainly speculation, I don't have benchmarking results to back this up

While "minifying" your keys technically would reduce the size of your memory/diskspace footprint, I think the advantages of this are quite minimal if not actually disadvantageous.

The first thing to realize is that data stored in Mongodb is actually not stored in its raw JSON format, its actually stored as pure binary using a standard know as BSON. This allows Mongo to do all sorts of internal optimizationsm, such as compression if you're using WiredTiger as your storage engine (thanks for pointing that ouT @Jpaljasma).

Second, lets say you do minify your keys. Well then you need to minify your keys. Every time. Forever. Thats a lot of work on your application side. Plus you need to unminify your keys when you read (because users wont know what n is). Every time. Forever. All of a sudden your minor memory optimization becomes a major runtime slowdown.

Third, that minifying/unminifying process is kinda complicated. You need to maintain and test mappings between the two, keep it tested, up to date, and never having any overlap (if you do, thats the end of all your data pretty much). I wouldn't ever work on that.

So overall, I think its a pretty terrible idea to minify your keys to save a couple of characters. Its important to keep the big picture in mind: the VAST majority of your data will be not in the keys, but in the values. If you want to optimize data size, look there.