Query-aware compression of join results

摘要

A method is provided for compressing results of a join query. A join order of a result set is determined from the join query, where the result set includes a plurality of tuples. A plurality of dictionary entries for the result set is received. A nested hierarchy of dictionaries is created based on the join order and the dictionary entries. A plurality of encoded tuples is received. The nested hierarchy of dictionaries is used by a processor to decode the plurality of encoded tuples so as to produce the plurality of tuples of the result set.

主权项

1. A computer-implemented method, with a decoder, for decompressing results of a join query, the method comprising:
receiving, from a result set encoder, a result set from the join query; receiving a plurality of encoded tuples associated with the result set, wherein each encoded tuple of the plurality of encoded tuples is received with a set of dictionary entry information, a set of dictionary entry information comprising a value from a dictionary entry generated by the result set encoder and a location within a set of nested hierarchy of dictionaries to store the value, and wherein each encoded tuple in the plurality of encoded tuples comprises a sequence of values, where each value in each sequence of values corresponds to a position of an entry within a nested hierarchy dictionary in the set of nested hierarchy of dictionaries, and wherein a position of each value in each sequence of values corresponds to a position of a column within the nested hierarchy dictionary corresponding to the value, wherein each position in each encoded tuple of the plurality of encoded tuples is associated with a column identifier within the set of nested hierarchy of dictionaries, each column identifier of the column identifiers being associated with a different column in the result set; determining a join order of the result set from the join query; creating the set of nested hierarchy of dictionaries based on the join order and the set of dictionary entry information, wherein a nesting order of the dictionaries in the set of nested hierarchy of dictionaries corresponds to the join order of the result set, and wherein the creating comprising storing the value comprised within the set of dictionary entry information at the location within a dictionary of the set of corresponding nested hierarchy of dictionaries as identified by the dictionary entry information; using, by a processor, the set of nested hierarchy of dictionaries and the values from the set of dictionary entry information stored within the set of nested hierarchy of dictionaries to decode the plurality of encoded tuples so as to produce a plurality of decoded tuples of the result set; and decompressing the result set of the join query with the decoder.