Welcome to my DBMS Blog – the Blog about Oracle, database management systems and IT trends
Most of articles will be dedicated to Oracle database. I’ll cover Oracle database features and DBA strategy, data design and database management.
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The In-Memory Column Store feature that was introduced by Oracle in the database version 12c (22.214.171.124) brings the solution for accelerating performance of database-driven business decision-making to real-time speeds. Since it is an extra-license feature for which Oracle makes you pay around 50% on top of your CPU license (similar to RAC option), you probably ask yourself a few valid questions. Don’t we cache everything already in memory anyway? Is it really required for my application, my company? Will it work for my workload at all? In this post I’ll give you a short guideline and introduction into Oracle database In-Memory feature.
First of all me personally and so probably you do not know any database that works only on disk. Indeed we cache most of our data, code and intermediate results in memory already. Furthermore there are some extra Oracle database performance features that help you to achieve that fairly efficiently, for example:
– KEEP/RECYCLE Pools
– RESULT Cache
– 12c Big Table Caching
– 12c Full Database Caching
The key point of Oracle In-Memory is not “What to cache” but “How”. So the major difference of Oracle In-Memory Column Store is that it enables individual database segments to be loaded into memory in the compressed columnar format. This technique enables segment scans to perform much faster than the traditional on-disk formats, providing performance boost for analytical and reporting workload.
In case you want to engage Oracle Support in order to receive help in an issue resolution you have to submit a Service Request (SR) at My Oracle Support website (MOS). Below I share some best practices in this area collected from different training courses and my own experience.
Before creating Oracle MOS SR
When you have a question or issue, need help the solution may already be available on MOS or Internet.
So before creating an SR you can do a quick search in the MOS Knowledge Base and MOS Community Space, use OTN Forum or even Google it. I recommend however using MOS Community or Internet only if all below points apply:
- If you have a low severity question or if you are interested in discovering how to do something
- If you have been unable to locate an answer in the MOS Knowledge Base
- When you have knowledge or experiences to share with your peers
If the issue is critical, do not wait! Submit the SR immediately while in parallel doing your own investigation (ideally having 2 resources for these 2 tasks). In this case even if you find a solution yourself, it will be anyway worth to validate it through MOS SR.
Creating a well-defined SR
1) Create an MOS SR using following methods:
- Using a relevant System/Target that is managed in MOS via Oracle Configuration Manager (OCM): <Systems> Tab -> Right-Click on System or Target -> Create SR
- Using “Create SR Like Selected SR” (best method in case a similar SR for the same target exists already)
- Using “Create SR” button to create SR from scratch
2) Provide all the necessary information that enables the SR to be correctly assigned to the engineer with the best skillset to resolve your issue.
SR Step – Problem
- Problem Summary = Tittle of the SR (use as short SR explanation; try to be descriptive to distinguish it in the SR List later; include Error codes)
- To speed up SR creation you can Autofill the Configuration/Software section using “SR Profile” or “Existing SR”.
- Choose carefully [Problem type] to ensure the SR assigned to the most appropriate and qualified support engineer available which will minimize the potential number of SR transfers and decrease the resolution time.
Below is a quick summary (OnePager) of the most valuable tips and best practices in order to speed up an Oracle Support (MOS) Service Request (SR) resolution:
- Speed up SR creation using:
– Use OCM and System/Target list -> Right Click on a target -> Create SR button (best method for initial SR)
– “Create SR Like Selected SR” (best method in case a similar SR for the same target exists already)
– Using SR Profiles (as alternative in case both above methods are not available/appropriate)
- Provide proper SR description and problem type including all relevant logs, traces, screenshots, etc. right at the beginning
- Open SR with Severity 2 as minimum (in case you want the SR resolution will move during the day)
- Ensure the Oracle Support engineer is in similar time zone (unless it’s 24×7 SR), otherwise request SR reassignment
- Ask for the proper root cause analysis, path forward and detail action plan
- Respond to your action codes fast in SR (Customer Working, Solution Offered) to ensure the SR is moving
- Track Timelines in the SR body yourself (since MOS does not do it properly)
- Speed up communication with Support Engineer using alternative ways:
- Ask Support Engineer to open a chat
- Ask Support Engineer to open a web conference (get instructions from the engineer how to start it)
- Call Support Engineer (call Oracle Support and ask them to connect you to the Engineer)
- Raise SR Severity to 1 (24×7 or during business hours; it works also for test systems!)
- Escalate SR / Request Management Attention
If you have more valuable tips on how to speed up Oracle Support (MOS) Service Request (SR) resolution, share your ideas in comments and/or else like/share it with others.
In this article I’ll share an Oracle RMAN script to do restore and recovery an Oracle database from tape library using EMC NetWorker. Apply this RMAN template to different recovery situations you might have. Before looking into the RMAN script see my notes below:
– Read about Oracle Recovery Manager (RMAN) concepts
– Look at the corresponding RMAN backup script for NetWorker
– The recovery script should work for Oracle database 11g, 12c (maybe 10g)
– Oracle database name = ORCL
– I use 2 RMAN channels to speed up the recovery of database
– Recovery of spfile and/or control file is optional and depends on your recovery situation
– PARMS section includes instructions for EMC NetWorker server (depends on Networker server configuration)
– Choose appropriate database recovery scenario (by default -> compete DB recovery; I commented 3 options for incomplete DB recovery scenario)
– This script is independent from RMAN configuration parameters
Recovery Manager (RMAN) is an Oracle utility that you use to manage the backup, restore, and recovery operations on Oracle database. RMAN has a powerful command language that is independent of the operating system.
Recovery Manager has a command-line interface. Oracle Enterprise Manager (OEM) also provides a graphical user interface for the Recovery Manager. Recovery Manager can be used on databases of Oracle8 or later releases.
RMAN provides several features not available when you make user-managed backups with operating system commands:
- You can store frequently executed operations as scripts in the database.
- Using the incremental block-level backup feature you can limit the backup to only those blocks that have changed since the previous backup. This may also reduce the time it takes to perform recovery operations in ARCHIVELOG mode.
- You can use RMAN to manage the size of backup pieces and save time by parallelizing the backup operation.
- RMAN operations can be integrated with the scheduling of the operating system to automate backup operations.
- You can detect block corruption. The information relating to the block corruption that is detected during backup can be obtained by using the V$BACKUP_CORRUPTION and V$COPY_CORRUPTION dynamic views.
- RMAN provides performance enhancements such as:
-Automatic parallelization of backup, restore, and recovery operations
-No generation of extra redo during online database backups
-Backups that are restricted to limit reads per file, per second to avoid interfering with OLTP work
-Prevention of flooding of any one file with reads and writes while still keeping a tape drive streaming, using multiplexing
- RMAN has a media management API to work seamlessly with third-party media management tools interfacing with storage devices providing increased speed and reliability.
- Under the user-managed method you need to keep track of all database files and backups. In a recovery situations you must locate backups for each datafile, copy them to the correct place using operating system commands, and choose which logs to apply. RMAN manages these tasks automatically.