Facilitating data redistribution in database sharding

A system, comprising:

• a plurality of physical data stores;
• at least one computing device including a processor and a memory;
• and
• a data store management application executable in the at least one computing device, the data store management application comprising:
• logic that maintains a database of data that is horizontally partitioned into a set of first buckets using modulo-based assignments, a fixed number of the first buckets being stored in each one of the physical data stores;
• and
• logic that repartitions the database into a set of second buckets using modulo-based assignments, the number of second buckets in the set being a multiple of the sum of a positive integer and the quantity of the physical data stores, wherein the data in the database is unmoved between the physical data stores by repartitioning, wherein each of the first buckets is identified by a respective first bucket identifier i1, each of the second buckets is identified by a respective second bucket identifier i2, and data assigned to i1 are assigned to a subset of the set of second buckets selected according to the equation:
• i2=i1+k*n, where k is the number of first buckets and n is a non-negative integer less than the number of second buckets divided by k.

A method, comprising the steps of:

• maintaining a plurality of physical data stores corresponding to horizontal partitions of a database containing a plurality of data items, wherein each data item in the database is assigned to a respective one of a plurality of first buckets, the data items assigned to each respective first bucket are stored in a mapped one of the physical data stores;
• reassigning, by a computing device, for each of the first buckets, each one of the data items which are assigned to the first bucket to a second bucket in a corresponding subset of a set of second buckets, the corresponding subset being different for each first bucket, each of the second buckets in the corresponding subset being stored in the mapped one of the physical data stores corresponding to the first bucket, the number of second buckets in the corresponding subset being a fixed number for all of the first buckets;
• and
• wherein the data items are unmoved between the physical data stores by the reassigning step, and wherein each of the first buckets is identified by a respective first bucket identifier i1, each of the second buckets is identified by a respective second bucket identifier i2, and data assigned to i1 are assigned to a subset of the set of second buckets selected according to the equation:
• i2=i1+k*n, where k is the number of first buckets and n is a non-negative integer less than the number of second buckets divided by k.