Each non-clustered table has a data segment. All of the table's data is stored in the extents of its data segment. Each cluster has a data segment. The data of every table in the cluster is stored in the cluster's data segment.
What is the command to find the database that already present before connecting ?
ps -ef | grep oracle
On Unix the command is ps -aef | grep -i pmon
What is the use of archive log file? How will you apply archive log file? How does archive log file helps to make backup consistent?
A Archive log file is used to archive the filled redo log files. and used in recovery.
It is used in recovery but not in instance recovery.
Rest it is used to make database consistent after recovery by matching header of data file and control file checkpoint information.
Hello Ganesh,Q : What is the use of archive log file? A : It is used for Point In Time Database Instance Recovery. Q : How will you apply archive log file? A : Archive Log need...
Where does the process dumps information about the error?
Errors are stored in alert.log file it can be shecked using the parameter background_dump_dest
Use show parameter background_dump_dest
for path of the alert.log in trace directory
alerts will log to alert.log and alert trace files will be saved in $ORACLE_HOME/admin/bdump directory.
What is the back ground process in Oracle architecture
A background process maintain relationship between memory structure and physical structure of Oracle server. Started when Oracle instance is started. Consist of 5 mandatory and some optional backgro...
The Background process related to Oracle Architecture are as follows:1.DBWR(DATABASE WRITER) 2.LGWR(LOG WRITER) 3.SMON(SYSTEM MONITOR) 4.PMON(PROCESS MONITOR) 5.CKPT(CHECK POINT)6....
Physical architecture of Oracle
How we can determine the physical architecture of Oracle?
Oracle architecture consist of four structures: 1. Memory structure (SGA, PGA) 2. Process structure (user process, server process, background process) 3. Physical structure (data files, redo log files...
physical architecture of oracle?
physical architecture is nothing but the physical files is stored in database
1.Data file
2.Control file
3.redo log file
It is enough
What is the name of the back ground process that modifies the db buffer cache?
dbwn write to datafile not to data buffer cache
When update or any other changes occurs and it commits, CKPT forces DBWr to flush the dirty block from DB Buffer cache to data files..
A schema is collection of database objects of a user.
A schema is the set of objects (tables, views, indexes, etc) that belongs to an user account. It is often used as another way to refer to an Oracle account. Most Oracle database installations traditio...
schema is a collect of object (table,view,cluster etc) that belongs to an user account.
Either virtual table is a temporary table or v$ or Xv$ views
When does the lgwr writes all redo-enteries to the redo-log buffer?
lgwr writes from log buffer to log files not to log buffer..
Four conditions when LGWr writes from redo log cache to redo log files
1) 1/3 of redolog buffer is full
2) Every 3 secs
3) For every 1mb collections
4) When Commit occurs
What is the use of redo log information ?
The information in a redo log file is used only to recover the database from a system or media failure prevents database data from being written to a database's data files.
Redo log records the changes made in database. Redo logs is mainly used to recover data.
Hi,Redo log information is the one of the major pard of the database , at any time if the oracle server instance get aborted and then it need recovery, so at that time redo log plays a role to recover...
What is the diff b/w btree index and bitmap index
A B-Tree index stores the index value and the physical rowid of the row. The index values are arranged in the form of leaves. A B-Tree index is used most when the cardinality is high. A Bitmap index ...
For example suppose we have using many distinct value for particular column in that time using b-tree index.
Bitmap indexes which is used low cardinaties values .
For example suppose we have using gender or flag column in that time using bitmap index .
What are the characteristics of data files ?
A data file can be associated with only one database. Once created a data file can't change size.One or more data files form a logical unit of database storage called a tablespace.
In data files, we cant change the extent management, type of it. But we can change the storage space for it if we need after the database (tablespace) creation.
Steps for changing the size of the datafile.1. Change that datafile to offline. eg. SQL>ALTER DATABASE DATAFILE '/u02/oracle/rbdb1/stuff01.dbf' OFFLINE;2. Chang the size of the datafile. eg SQL>...
How does the smon process performs recovery after instance failure?
When shutdown abort happens, oracle server gets crashed. To recover from the crash, SMON will check the online Redo data files and last SCN no in the Redo log files and SCN number in the undo tablespa...
When the Oracle instance fails. The SMON process performs instance recovery at startup using the online redo log files.
What is priVATe database link ?
PriVATe database link is created on behalf of a specific user. A priVATe database link can be used only when the owner of the link specifies a GLobal object name in a SQL statement or in the definition of the owner's views or procedures.
database link is created by a user in his schema,it has 2 types
1.private database link
2.public database link /global
private database link is access the object in separate user
syntax:
create database link
Private database link is created by a user in his schema. While creating the link, the keyword GLOBAL is not used. The syntax for creation is CREATE DATABASE LINK myPrivateDBLink connect to
Private DB links can not be used by other schema's.
Regarding query and a view in Oracle
Hi, if a user executes a query which is already being used by a view exactly will Oracle use already existing view to retrieve data or use the query executed by user? regards, shashi
Oracle uses query executed by user because when you use a view name in an other query, it simply transform query. select empid,name from emp; --- original create view emp_view as select empid,name f...
Which parameter specifies the number of dbwn processes?
v$database
The initialization parameter DB_WRITER_PROCESSES specifies the number of DBWn processes. The maximum number of DBWn processes is 20. If it is not specified by the user during startup, Oracle determines how to set DB_BLOCK_PROCESSES based on the number of CPUs and processor groups.
Can a tablespace hold objects from different schemes ?
Yes.
Yes one tablespace can hold objects from different schemas.Eg. when we create any schema (user) than we can assign default tablespace like this for any user user we can use same tablespace. Eg. SYSTE...
Oracle database's data is stored in data blocks. One data block corresponds to a specific number of bytes of physical database space on disk.
Smallest logical of Oracle database. In Oracle 10g default data block size is 8192 byres means 8k.
Other data block size are 2k, 4k, 8k, 16k, 32k
We have only these available data blocks in oracle database.
Oracle Data Blocks is logical storage unit of Oracle and One Oracle Data Blocks containts multiple of Operating system Blocks. Data blocks contains contigous of Bytes.
The level of logical database storage above an extent is called a segment. A segment is a set of extents, each of which has been allocated for a specific data structure and all of which are stored in ...
it's you table, index and else