Correlated hash table probe icon

Correlated Hash Table Probe

The Correlated Hash Table Probe icon indicates that the selection criteria that match the key columns used to create the temporary correlated hash table will be probed to find all of the matching values stored within the hash table. A correlated hash table probe is generally considered when determining the implementation for a secondary table of a join. The use of a hash table probe will allow the optimizer to generate a plan that can take advantage of any non-join selection while creating the temporary correlated hash table. An additional benefit of using a correlated hash table probe is that the data structure of the temporary correlated hash table will usually cause the table data to remain resident within main memory after creation thus reducing paging on the subsequent probe operation.