Archive for September, 2023

The Case for Cardinality Bounds: Principled Conservatism in Query Optimization

Introduction In the last decade, the database community has identified cardinality estimation as the primary stumbling block for modern query optimizers.  Cardinality estimates, which estimate the size of sub-plan queries, are the primary basis for choosing between query plans, so poor estimates may result in catastrophic query execution plans. Research on this topic has consistently […]