Question

In our app, we download about 48 sqlite files each around 300kb in size and save it to the disk. When user goes into a module, a subset of the data from the any of the file is read and displayed based on some conditions. As the user scrolls around in the module, when the scrollview stops scrolling, we determine the position where it stopped and accordingly query the appropriate sqlite file to get the data and display on screen. This takes about 2 sec to show the data to the user.
We want to optimize this and I have read that querying CoreData instead of sqlite files can make this faster.

So, the question is, should we try to put data from each sqlite file into CoreData and then always query CoreData. My concern is that it would be too much data that would need to be inserted this way since we have 48 files. The other approach is only the subset of data that is fetched should be loaded to CoreData and not all the files. But this would mean that before displaying the data we determine whether it was already fetched and available in CoreData, else we query sqlite.
Any suggestions as to what would be a better way to go?

Answer 1

With the amount of info you’ve provided, it’s not possible to really see whether Core Data would make sense for your application. You would have to provide a good amount of info for anyone else to have really well-informed opionion on the matter — and a decision such as this is important.

Btw, you seem to be under the impression that all the data would have to go in gigantic database file in Core Data – this isn’t the case. You can have many managed object model files (these are end-product persisted database files for Core Data, named .xcdatamodeld) and open them selectively.

Your best bet is to do some research, try and find the crucial differences between Core Data and use of SQLite directly. They both have their place. Core Data is great in the right circumstance — it’s not a relational database, it’s an object graph and persistence manager, and that has important implications. Core Data has been optimised to the moon and back, so if you use it in the correct circumstances, it’s great — good performance and does some heavy lifting to stop you having to. But in other circumstances, direct use of SQLite would be a better option. See, for example, this blog post about someone who switched away from Core Data to SQLite.

Also check out this nice article on the differences. And of course read Apple’s own guides, and the wikipedia page.

It’s hard for us to answer the question you’ve asked, but if you have queries about certain more specific aspects of Core Data, post some new questions — that sort of question is easier to answer.