Don’t store arrays of numbers in Indexed DB – use base64 instead

Following on from Keep your Indexed DB keys and values small if you want good performance!, here is another thing I’ve learned about Indexed DB performance (in January 2024):

If you have a long list of numbers to store, don’t put them in a JavaScript array – instead encode them to base64.

Here are the numbers:

On Firefox, storing the same set of numbers as an array is much slower than encoding them as base64.

On Chromium, storing the same set of numbers as an array is much slower than encoding them as base64.

These graphs show that in both Firefox and Chromium (at time of writing), it is much faster to count the records in an Indexed DB store if the list of numbers inside each record is encoded as a base64 string instead of being included directly as a JavaScript array.

The interactive 3D(!) graphs are here: artificialworlds.net/indexed-db-perf/arrays.html and the source code is at codeberg.org/andybalaam/indexed-db-perf.

See also: Keep your Indexed DB keys and values small if you want good performance! and Deleting an Indexed DB store can be incredibly slow on Firefox.