IO Sort Cost Calculation
IO Sort Cost Calculation: formulae and internals Continue Reading
Oracle
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
Join Permutations Heatmaps
Generating heatmaps for join permutations using Python Continue Reading
Comparing TSQL and PL/SQL Performance
Why Oracle outperforms SQL Server Continue Reading
Correlated Subqueries in the SELECT Clause (2)
Examples where Oracle optimizer doesn’t unnest subqueries in the SELECT clause Continue Reading
Correlated Subqueries in the SELECT Clause
How Oracle and SQL Server optimize correlated subqueries in the SELECT clause with an example how to manually optimize such queries for Oracle. Continue Reading
Tracking the Optimizer with gdb
Tracing a low-level Oracle C function for getting insights into the optimizer decision making Continue Reading