Overhead of SQLNet encryption on RMAN duplicate
SQLNet encryption has a significant impact on RMAN duplicate duration. Continue Reading
Oracle
Excessive query parsing time with extended statistics and long in-lists
Excessive query parsing time with extended events and long in lists were observed on a 12c database. As a workaround set the undocumented parameter _optimizer_extended_stats_usage_control to 224. Continue Reading
Avaloq Database Crash
Setting session level to zero can crash the database if there are local JDBC connections from the application users (i.e. users that are registered in K.SEC_USER and at the same time a core database background process is running under the PID 1234. Continue Reading
Stale index statistics
The gathering of empty schema statistics might cause index statistics to be marked as stale. 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
Making local connection to Oracle database with DBD::Oracle and instant client
The purpose of this post is to explain how to make a local connection using the DBD::Oracle Perl CPAN module which is linked with an Oracle instant client. Continue Reading