Data compression using dictionaries

Data units of a dataset may be compressed by clustering the data units into clusters, selecting a reference unit for each unit cluster, and compressing data units of each unit cluster using the reference unit of the unit cluster as a dictionary. The computational efficiency of the clustering algorithm may be improved by not applying it to data units themselves, but rather to hash values of the data units, where the hash values have a much smaller size than the data units. The hash function may be a locality-sensitive hash (LSH) function. The reference unit of a cluster may be determined in any of a variety of ways, for example, by selecting a centroid or exemplar of the cluster. Clusters, including their references values, may be indexed in a cluster index (e.g., a Faiss index), which may be searched to assign future added or modified data units to clusters.