https://docs.elrond.com/developers/best-practices/storage-mappers/
Use SingleValueMapper when:
you need to read the whole array on every use
the array is expected to be of small length
Use VecMapper when:
you only require reading a part of the array
T's top-encoding is vastly more efficient than T's nested-encoding (for example: u64)
Barely. You're literally doing what VecMapper does, but not storing the length.
https://docs.elrond.com/developers/best-practices/storage-mappers/ Use SingleValueMapper when: you need to read the whole array on every use the array is expected to be of small length Use VecMapper when: you only require reading a part of the array T's top-encoding is vastly more efficient than T's nested-encoding (for example: u64)