Have you ever tried to drop or rename a postgres database or even create another database from one as a template, only to be confronted by the dreaded message: postgres=# create database test with template a_database; ERROR: source database “a_database” is being accessed by other users DETAIL: There are 40 other sessions using the database. …
Oracle services were a feature introduced in Oracle 10g. Their function is to simplify workload management by allowing you to group applications that share traits such as thresholds, priorities and attributes. The Oracle database is presented as a service and so you always have at least one service running. It is good practice to create …
Oracle ASM keeps redundancy quite simple by providing only 3 options. you can choose to have no redundancy or mirroring provided by the ASM instance. This is the ‘External’ option and assumes that you are handling mirroring somewhere else perhaps through hardware raid on your storage network. You can chose ‘normal’ 2 way mirroring r …
The process for modifying a votedisk that is stored on ASM differs from the process when the votedisk is stored on some other medium. When your voting disks are stored on ASM you can move them off to non ASM storage with the replace command: $ crsctl replace votedisk [path_to_new_votedisk] (this can be done from …
An ASM instance forms and presents is the underlying structure for an ASM dynamic volume. ASM provides a disk group which is really a logical container for physical space. ASM is very efficient at storing data files but there are many types of files that cannot be stored on ASM and it cannot be read …
An ASM instance has its own SGA but it is not the same as the SGA in a database instance. The 4 main sections of the SGA in an ASM instance are: ASM Cache – this is used during rebalancing operations for reding and writing blocks. Large Pool – Used for Parallel Operations. Shared Pool …
You cannot simply add more copies of voting disks to increase redundancy because the number of voting disks is managed by Oracle ASM and determined by the redundancy of the disk group. To increase the number of voting disks, you need to move them to a disk group with higher redundancy. So, create the new …
Oracle CRS backs up the OCR automatically at regular intervals. The standard backup frequency and retention policies are Every 4 hours – keeping the last 3 copies. Every day (at the end) – keeping the last 2 copies. Every week (at the end) – keeping the last 2 copies. You can find the location …
SQL performance analyzer performs a similar job to the SQL Tuning Advisor with one major difference, SQL performance analyser allows you to compare the performance of SQL statements before and after a change, allowing you to predict the impact of changes to the system on SQL performance as well as pre tuning your database before …
The automated tuning process in Oracle 11g is implemented by a number of functions in the Oracle database: Automatic Database Diagnostic Monitor (ADDM) Takes input from the AWR reports which it analyses in order to identify potential bottlenecks. If the statistics level parameter is set to TYPICAL or ALL then the ADDM is ran …