There are many cases where we have some data we would like to interrogate where using SQL would make it easier to fetch data. However we would like to make things fast. Having all the data in memory is always much faster than having it on disk. Even with modern SSD-based disks.

SQLite allows us to create a database entirely in memory.

Of course this means the amount of data we can hold is limited to the available free memory and the data, in this format, will be lost once the process ends.

Nevertheless it can be very useful as temporary data storage instead of using hashes, arrays.