Sap Se

Kang Woo Choi

Dong Hun Lee

Oliver Rebholz

Minseon Ahn

Jungmin Kim

Daeun Lee

Mechanisms are disclosed for estimating cardinality of group-by queries. A probability of occurrence of values is obtained for columns that satisfy the query occurring in tables from a trained machine learning model. A range selectivity is calculated based on a conditional probability of occurrence of the values. A set of valid generated sample tuples is generated from the trained machine learning model. A group-by selectivity is calculated by keeping the conditional probability of occurrence to obtain probabilities that a result set will have specific group-by column values associated with the tables while proceeding with progressive sampling. A sampling probability is calculated by normalizing the group-by selectivity by dividing the group-by selectivity by the range selectivity. The samples are filtered such that the samples having a sampling probability below a sampling probability threshold are filtered out. A sampling-based estimator is applied to the filtered samples set to estimate the cardinality.

Database group-by query cardinality estimation

Despite the increase of memory capacity and CPU computing power, memory performance remains the bottleneck of in-memory database management systems due to ever-increasing data volumes and application demands. Because the scale of data workloads has out-paced traditional CPU caches and memory bandwidth, one can improve data movement from memory to computing units to improve performance in in-memory database scenarios. A near-memory database accelerator framework offloads data-intensive database operations via or to a near-memory computation engine. The database accelerator's system architecture can include a database accelerator software module/driver and a memory module with a database accelerator engine. An application programming interface (API) can be provided to support database accelerator functionality. Memory of the database accelerator can be directly accessible by the CPU.

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Seoul, South Korea

Kang Woo Choi