Oracle Corporation
Limited memory and statistics resilient hash join execution

Abstract:

A processor receives a payload array and generates a hash table in a cache that includes a hash bucket array. Each hash bucket element contains an identifier that defines a location of a build key array element in the payload array. For a particular build key array element, the processor determines a hash bucket element that corresponds to the payload array. The processor copies the identifier for particular build key array element into the hash bucket element. If the cache is unable to insert additional build key array elements into the hash table in the cache, then the processor generates a second hash table for the remaining build key array elements in local volatile memory. When probing, the processor probes both hash tables in the cache and local volatile memory for identifiers in hash bucket elements that are used to locate matching build key array elements.