Category Archives: Oracle Database

An Oracle database is a collection of data treated as a unit. The purpose of a database is to store and retrieve related information. A database server is the key to solving the problems of information management.Many companies has implemented their data in Oracle. Most of them are mission critical. So Oracle database concept need to be very clear to manage these mission critical things. At the same time Oracle database needs to deliver high performance also. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.

Below section I have tried to present all the important features in Oracle Database management

Oracle DBA: How to schedule jobs in Oracle Database

Last updated on August 31st, 2016 at 05:09 pmWe often wants to run pre-defined jobs at different schedule. Oracle database provides dba_jobs/dbms_scheduler (Oracle Database job scheduler) for the scheduling of pre-defined jobs. Information about DBA_JOBS ( Till 9i) Query to see the jobs running through dba_jobs select /*+ rule */ * from dba_jobs_running; or select /*+ ordered */ * from dba_jobs_running; Common Reason why jobs don’t execute … Continue reading Oracle DBA: How to schedule jobs in Oracle Database »

11g Alert log new features

Last updated on November 28th, 2015 at 11:58 am11g Alert log new features Beginning with Release 11g of Oracle Database, the alert log is written as both an XML-formatted file and as a text file, as in earlier releases.Both these log files are stored inside the ADR home.The ADR root directory is known as ADR BASE.The Automatic Diagnostic Repository (ADR) is a directory structure that … Continue reading 11g Alert log new features »

How to recreate redo log files

Last updated on September 15th, 2016 at 05:30 amWe often get situation where we need to increase the size of the redo log files as log switches are very frequent.Increasing the redo log files sizes decreases the log switches and  improves the performance of the database.There is no resize command for redo log files, it has to be recreated inorder to increase or decrease the … Continue reading How to recreate redo log files »

Top 5 ASM queries every DBA should know

Last updated on August 24th, 2016 at 06:48 pmASM is being used as storage environment in various organization.Here are Top 5 ASM queries every DBA  should know QUERY TO FIND THE FILES IN USE BY AN ASM INSTANCE col full_path format a50 col full_alias_path format a50 SELECT concat(‘+’||gname, sys_connect_by_path(aname, ‘/’)) full_alias_path FROM (SELECT g.name gname, a.parent_index pindex, a.name aname, a.reference_index rindex FROM v$asm_alias a, v$asm_diskgroup g … Continue reading Top 5 ASM queries every DBA should know »

Oracle DBA:RMAN basetables

Last updated on August 31st, 2016 at 05:12 pmRMAN is a powerful tool for taking backup .It maintains all the backup related informations oin Rman basetables in Rman catalog.We are listing all  tables and views are which  are vgenerated in the catalog database. Use the DESCRIBE command for each table or view to display column information.We have given some explanation for each table so that … Continue reading Oracle DBA:RMAN basetables »

Oracle Advanced Queuing

Last updated on November 23rd, 2015 at 01:28 pmOracle Advanced Queuing provides message queuing as an integrated part of the Oracle Server, thereby creating a message-enabled database. Oracle uses the following components to deliver AQ fuctionality: Message A message is the smallest unit of information inserted into and retrieved from a queue. It contains user data (payload) in the form of an object type, and … Continue reading Oracle Advanced Queuing »

Oracle Parallel Query Option

Last updated on September 14th, 2016 at 09:19 pmWhat Parallel Query Option can perform 1.To speed up access to data by using multiple processes 2.To maximise machine resource usage in query processing 3.To reduce elapsed time by increasing resource usage Operations That Can Run with Parallel Query Option 1.Parallel 2. Full table scans  or table move 3.Fast full index scans 4.Create index or rebuild index 5.Create table … Continue reading Oracle Parallel Query Option »

How Oracle RAC handles instance failure and recovery

Last updated on August 31st, 2016 at 05:37 pmOracle uses a simple mechanism of a heartbeat to detect instance failure of a node in a RAC cluster. The cluster manager software detects if it cannot receive the heartbeat of the other instances and if it does not the recovery process begins. From what I can find, this heartbeat is provided by the udlm package on … Continue reading How Oracle RAC handles instance failure and recovery »

Latches

Last updated on November 14th, 2015 at 02:46 pmINTRODUCTION Latches are low level serialization mechanisms used to protect shared data structures in the SGA. The implementation of latches is operating system dependent, particularly in regard to whether a process will wait for a latch and for how long. A latch is a type of a lock that can be very quickly acquired and freed. Latches … Continue reading Latches »

Oracle Enqueue:Mechanism used to protect shared resource

Last updated on August 24th, 2016 at 06:39 pmThe oracle server uses different type of locks(Enqueue) to prevent concurrent access to the data and to prevent destructive interference between the uses Following types of locks are available in Oracle Server a. Data Manipulation Locks: its protect the data.Table locks protects the entire table while the row lock protect the selected row b.Data Doctionary locks-Its protect … Continue reading Oracle Enqueue:Mechanism used to protect shared resource »

Oracle Performance Tuning Tools( Oracle Explain Plan,Auto-trace,tkprof)

Last updated on September 14th, 2016 at 09:08 pmWe are presenting here All information about Oracle Performance Tuning Tools like Oracle Explain Plan,Auto-trace,tkprof. We will take a deep dive into each of them Oracle Explain Plan -Oracle database internally creates a query execution plan in order to fetch the desired data from the physical tables. The query execution plan is nothing but a set of methods on … Continue reading Oracle Performance Tuning Tools( Oracle Explain Plan,Auto-trace,tkprof) »