Simple-SDS 0.3.0

Compressed multisets

• Elias-Fano encoding can store duplicate values, which simplifies some uses of SparseVector.
• Built with SparseBuilder::multiset or SparseVector::try_from.
• Most bitvector operations generalize from sets to multisets naturally, but rank_zero does not work.
  • If there are multiple occurrences of value i, the predecessor of i has a higher rank than its successor.

Interface changes

• select and related queries return Option instead of Result.
• Element trait is now Vector.

Other

• Vectors have items instead of elements to avoid confusion between vector elements and serialization elements.
• Uses rand 0.8 instead of 0.7.
• Serialization improvements:
  • skip_option, absent_option, and absent_option_size for dealing with optional structures.
  • test for running basic serialization tests for a new type.