Suboptimal Sort Calculation
Beware of the suboptimal sort cost calculation in SQL Server. Comparison with Oracle included. Continue Reading
cost based optimizer
Old-Style (non-cost-based) Join Predicate Push-Down Transformation Part 2 (Recursive WITH)
Wrong cost calculation with recursive WITH subquery and OJPPD Continue Reading
Cost Propagation Errors
Reporting optimizer mistakes where the cost of operations in the execution plan wasn’t propagated to their parents Continue Reading
Old-style (non-cost-based) Join Predicate Push-Down Transformation
Suboptimal execution plans after falling back to OJPPD with hierarchical subqueries Continue Reading
IO Sort Cost Calculation (2)
Interpreting formulae; comparison to full table scan calculation Continue Reading
IO Sort Cost Calculation
IO Sort Cost Calculation: formulae and internals Continue Reading
Extracting Join Order from Optimizer Trace
Programmatically extracting join order information from optimizer trace Continue Reading
Extracting Query Block Information from Optimizer Trace
Programmatically extracting the query block information from the optimizer trace Continue Reading
Scalar Subqueries with OUTER JOIN
Wrong cost calculation when an OUTER JOIN drives the execution of a correlated scalar subquery in SELECT DISTINCT Continue Reading
Join Predicate Push Down Additional Phase
Analyzing Join Predicate Push Down Additional Phase by using the optimizer trace Continue Reading