This chapter discusses hash indexes, the new type of indexes introduced in the In-Memory OLTP Engine. It will show their internal structure and explain how SQL Server works with them. You will learn about the most critical property of hash indexes, bucket_count, which defines the number of hash buckets in the index hash array. You will see how incorrect bucket count estimations affect system performance. Finally, this chapter talks about the SARGability of hash indexes and statistics on memory-optimized tables.
Hashing is a widely-known concept in Computer Science that performs the transformation of the ...