What Are Query Optimization Statistics?
Statistics for query optimization are objects that contain statistical information about the distribution of values in one or more columns of a table or indexed view. The query optimizer uses these statistics to estimate the cardinality, or number of rows, in the query result. These cardinality estimates enable the query optimizer to create a high-quality query plan. For example, the query optimizer could use cardinality estimates to choose the index seek operator instead of the more resource-intensive index scan operator, and in doing so improve query performance.Each statistics object is created on a list of one or more table columns and includes a histogram displaying the distribution of values in the first column. Statistics objects on multiple columns also store statistical information about the correlation of values among the columns. These correlation statistics, or densities, are derived from the number of distinct rows of column values. For more information about statistics ob
