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coders
Every coder has two different encoding modes, though they may share the same implementation:
- Index key mode, which produces a binary-sortable representation for usage in index building
- Value mode, which produces a reversible representation for actual data storage
Both modes should result in a Buffer and optionally an auxiliary blob (for out-of-band blob storage).
Index key mode
Technical priorities and requirements:
- Must be binary-sortable; that is, upon sorting a list of encoded representations, its order must match that of the original corresponding inputs if those were to be lexicographically sorted (according to the sorting rules for their data type).
- Must be deterministic; the same input value must result in the same encoded representation every time. If there is a controllable form of non-determinism (eg. a versioned set of sorting rules such as DUCET), it must be possible to regenerate the index keys for all existing values with the new version of the encoding.
- Must be space-efficient.
- Prioritize encoding speed over other (non-required) characteristics such as reversibility.
Value mode
Technical priorities and requirements:
- Must be reversible; ie. it must be possible to losslessly decode the encoded representation back into its original value.
- Must be space-efficient.
- Prioritize decoding speed over encoding speed (within reasonable bounds) as well as other (non-required) characteristics such as binary-sortability.