There are two key tools for tuning PolyBase queries from within SQL Server: statistics and execution plans. In this chapter, we will see how statistics on external tables can allow SQL Server’s query optimizer to make better decisions regarding predicate pushdown and join order. Then, we will dig into execution plans, which will provide us information critical for optimizing query performance.
Statistics in SQL Server
SQL Server’s query optimizer makes use of statistics to gain information on the distribution of data for a column or set of columns on a table without needing ...
