What type of data will be more optimal for a field where 1 digit will be used?

Question

MongoDB

Do you mean int or string (with a minimum and maximum value)? Int 32-bit.
By 1 digit it means that the value will be from 0 to 9, 1 character.
What will eat less memory?

Answer 1

mongodb supports compression, so store in int (and values ​​​​from 0 to 9 and not a character code) then zeros in the database will be optimized and compressed
if you need to store a lot of data within one document - use BinData this is bson serialization, it seems to be very efficient
well and if you just need to store a list of numbers in the document, then the
ps lines my gut senses that an inappropriate tool is being used for the task