A good DBA will study and think!
Oracle recommends that you use Database Configuration Assistant (DBCA) to create your Oracle RAC database, because DBCA’s preconfigured databases optimize your environment for features such as ASM, the server parameter file, and automatic undo management. DBCA also provides pages to create new ASM disk groups if they are needed; if you use ASM or cluster file system storage, then DBCA also configures recovery and backup disk space.
Continue reading “Custom DB creation on RAC.”AWR- Automatic Workload Repository report shows the data captured between two point in time (Two snapshots).
Here I will be discussing about AWR report generation using sqlplus.
We have seven sql files to generate AWR reports, means in six different way we can generate this report.
The list is from the 11.2.0.2 home ($ORACLE_HOME/rdbms/admin) with (mostly) the one-line description. I’ve put the most useful ones in the first list:
For the export operations described in this section, it is assumed that the user is using Oracle Database Enterprise Edition and the wildcard option with the DUMPFILE parameter.
In a typical export that includes both data and metadata, the first worker process will unload the metadata: tablespaces, schemas, grants, roles, tables, indexes, and so on. This single worker unloads the metadata, and all the rest unload the data, all at the same time. If the metadata worker finishes and there are still data objects to unload, it will start unloading the data too.
Oracle Data Pump, available starting in Oracle Database 10g, enables very high-speed movement of data and metadata from one database to another. One of the most useful features of Data Pump is the ability to parallelize the work of export and import jobs for maximum performance.
The Data Pump Export and Import (expdp and impdp) PARALLEL parameter can be set to a value greater than one only in the Enterprise Edition of Oracle Database. A user must be privileged in order
to use a value greater than one for this parameter. (In Standard Edition, the PARALLEL parameter is limited to one.) It is most useful for big jobs with a lot of data relative to metadata. Small jobs or jobs with a lot of metadata will not see significant improvements in speed.
Metadata is never unloaded in parallel, but is sometimes loaded in parallel. There are two situations when metadata is loaded in parallel:
• Multiple workers will load package bodies in parallel.
• One worker will create all the indexes and use Parallel Execution Processes (PX processes) to speed up the work.
In Data Pump terminology, a table data object is the basic unit of storage.
In the Oracle RDBMS environment, redo logs comprise files in a proprietary format which log a history of all changes made to the database. Each redo log file consists of redo records. A redo record, also called a redo entry, holds a group of change vectors, each of which describes or represents a change made to a single block in the database.
For example, if a user UPDATEs a salary-value in a table containing employee-related data, the DBMS generates a redo record containing change-vectors that describe changes to the data segment block for the table. And if the user then COMMITs the update, Oracle generates another redo record and assigns the change a “system change number” (SCN).
So whenever Oracle throws the following error, it means that Redo is corrupted.
Continue reading “Redo log corruption”Oracle consists of various logical and physical structures, namely :
At the finest level of granularity, Oracle stores data in data blocks (also called logical blocks, Oracle blocks, or pages). One data block corresponds to a specific number of bytes of physical database space on disk. You set the data block size for every Oracle database when you create the database. This data block size should be a multiple
of the operating system’s block size within the maximum limit. Oracle data blocks are the smallest units of storage that Oracle can use or allocate.
Oracle manages the storage space in the datafiles of a database in units called data blocks. A data block is the smallest unit of data used by a database. In contrast, at the physical, operating system level, all data is stored in bytes. Each operating system has a block size. Oracle requests data in multiples of Oracle data blocks, not operating system blocks. Continue reading “Demystifying Oracle Data Block – 1”
Oracle consists of various logical and physical structures, namely :
At the finest level of granularity, Oracle stores data in data blocks (also called logical blocks, Oracle blocks, or pages). One data block corresponds to a specific number of bytes of physical database space on disk. You set the data block size for every Oracle database when you create the database. This data block size should be a multiple
of the operating system’s block size within the maximum limit. Oracle data blocks are the smallest units of storage that Oracle can use or allocate.
Know more about Oracle Datablock.
Continue reading “De-mystifying the Oracle Data Block – 2”
A flat file is an archive of data that does not contain associations with various records or is a non-social database. A better than average instance of a level record is lone substance simply archive that contains each one of the data required for a program that is frequently secluded by some kind of delimiter. A level database is fundamentally less requesting to understand and setup than a customary database, however, may need for any program that is a great part of the time used or contains countless. Continue reading “Introduction to DBMS and RDBMS”
This is for them the people who are needing to start as an Oracle DBA. If they have to make a sensible picture of Oracle Architecture by then, in particular, they need to perceive what is SQL query lifecycle in Oracle. So lets deep dive and try to figure out how exactly a query works.
Continue reading “What exactly happens when you fire a query?”
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