Top 5 wait events from v$active_session_history

This query returns the top 5 wait events for the last hour from v$active_session_history view. Be careful, this view is part of the diagnostic pack, you should not query this view if you don’t have license for it. Top 5 wait events from v$active_session_history [crayon-5473514c88282132866302/] This is obviously an approximation, because v$active_session_history contains only 1 second samples, […]

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OCP 12C – Oracle Data Redaction

What is Oracle Data Redaction ? Oracle Data Redaction is meant to mask (redact) sensitive data returned from application queries. Oracle Data Redaction doesn’t make change to data on disk, the sensitive data is redacted on the fly before it is returned to the application. You can redact column data by using one of the following methods: Full [...]

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OCP 12C – Resource Manager and Performance Enhancements

Use Resource Manager for a CDB and a PDB Managing Resources between PDBs The Resource Manager uses Shares ans Utilization limit to manage resources allocated to PDBs. The more “Shares” you allocate to a PDB, the more resource it will have. Shares are allocated through DBMS_RESOURCE_MANAGER.CREATE_CDB_PLAN_DIRECTIVE. One directive can only concern one PDB and you can’t [...]

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OCP 12C – SQL Enhancements

Extended Character Data Type Columns In this release Oracle changed the maximum sixe of three data types  In Oracle 12c if you set a VARCHAR2 to 4000 bytes or less it is stored inline, if you set it to more than 4000 bytes then it is transformed in extended character data type and stored out [...]

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OCP 12C – DataPump, SQL*Loader, External Tables Enhancements

Oracle DataPump Enhancements Full Transportable Export and Import of Data In Oracle 12c you now have the possibility to create full transportable exports and imports. A full transportable export contains all objects and data needed to create a copy of the database. To create a fully transportable export of your database you need to specify [...]

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OCP 12C – Partitioning Enhancements

Online Partition operations Table Partitions and subpartitions can now be moved online. [crayon-5447caf7d0323514534927/] Compression options can also be added during an online partition move. [crayon-5447caf7d034e673459253/] Reference Partitioning Enhancements Truncate or Exchange Partition with Cascade option With Oracle 12c, it is now possible to use the CASCADE option to cascade operations to a child-referenced table when [...]

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OCP 12C – Index and Table Enhancements

Table Enhancements Oracle 12c offers you to create invisible columns, these columns are not visible until you explicitly mention their names in the SQL statement. This functionnality allows developpers to make change to the database without conflicting with the existing application. To create an invisible column: [crayon-544665ad911af900442543/]  You can’t create invisible columns on : External [...]

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OCP 12C – ADR and Network Enhancements

ADR enhancements In oracle 12c the Automatic Diagnostic Repository contains a new log directories with 2 subdirectories : DDL Debug The DDL log When you active the DDL logging in Oracle 12c using enable_ddl_logging=true, Oracle writes all DDL operations into the specific DDL log instead of writting it to the alert log. To enable DDL logging [...]

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OCP 12C – Emergency Monitoring, Real-Time ADDM

Emergency Monitoring Emergency monitoring is meant for extreme circumstances where it’s impossible for you to connect to the database because the database is hung. Emergency monitoring allows you to connect to the database in diagnostic mode and run a lightweight analysis to see what’s happening. You can access real-time performance data from ASH and access [...]

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OCP 12C – SQL Tuning

What’s new ? Oracle 12c introduces a major update called Adaptive Query Optimization which is based on : Adaptive execution plans Adaptive Statistics These two functionnalities are used to improve execution plans by using dynamic statistics gathered during the first part of the SQL execution. This allow to create more efficient plans that those using [...]

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