Fast Retrieval of DYNAMIC_SAMPLING_RESULT Information
Correlating an active dynamic sampling trace with the data dictionary Continue Reading
adaptive query optimization
Join Cardinality Misestimate (“Adjustment-to-Zero Issue”) in Oracle 12.2 – Part 2
Enhanced example of join cardinality misestimate caused by adjustment-to-zero issue Continue Reading
JOIN CARDINALITY MISESTIMATE in Oracle 12.2
Wrong join cardinality estimate due to adaptive dynamic sampling Continue Reading
SQL plan directives on partitioned tables
The purpose of this post is to warn of an edge case where the cardinality estimate might significantly increase after adding a conjunctive filter predicate. This problem might arise in Oracle 12c due to sql plan directives on partitioned tables when there is a value which is rare in one partition, but appears frequently in other partitions. Continue Reading
Temp table transformation and SQL plan directives
Temp temporary transformation is the operation in the execution plan where Oracle stores the subquery results in a temporary table. Cardinality estimates can get different if the temp table transformation is used in Oracle 12c. The purpose of this post is to explain why this happens. Continue Reading