1) What is oracle database ?
Oracle Database is a relational database management system (RDBMS) which is used to store and retrieve the large amounts of data. Oracle Database had physical and logical structures. Logical structures and physical structures are separated from each other
Oracle Database is a relational database management system (RDBMS) which is used to store and retrieve the large amounts of data. Oracle Database had physical and logical structures. Logical structures and physical structures are separated from each other
2)
What is schema?
A user account and its associated data including tables, views, indexes, clusters, sequences,procedures, functions, triggers,packages and database links is known as Oracle schema. System, SCOTT etc are default schema's. We can create a new Schema/User. But we can't drop default database schema's. 3)
A user account and its associated data including tables, views, indexes, clusters, sequences,procedures, functions, triggers,packages and database links is known as Oracle schema. System, SCOTT etc are default schema's. We can create a new Schema/User. But we can't drop default database schema's. 3)
3)
What is a Tablespace?
Oracle use Tablespace for logical data Storage. Physically, data will get stored in Datafiles. Datafiles will be connected to tablespace. A tablespace can have multiple datafiles. A tablespace can have objects from different schema's and a schema can have multiple tablespace's. Database creates "SYSTEM tablespace" by default during database creation. It contains read only data dictionary tables which contains the information about the database.
Oracle use Tablespace for logical data Storage. Physically, data will get stored in Datafiles. Datafiles will be connected to tablespace. A tablespace can have multiple datafiles. A tablespace can have objects from different schema's and a schema can have multiple tablespace's. Database creates "SYSTEM tablespace" by default during database creation. It contains read only data dictionary tables which contains the information about the database.
4) What is a Control File ?
Control file is a binary file which stores Database name, associated data files, redo files, DB creation time and current log sequence number. Without control file database cannot be started and can hamper data recovery.
Control file is a binary file which stores Database name, associated data files, redo files, DB creation time and current log sequence number. Without control file database cannot be started and can hamper data recovery.
5)
Define data blocks ?
Data Blocks are the base unit of logical database space. Each data block represents a specific number of bytes of database space on a disk
6) What is an Extent ?
Extent is a collection of Continuous data blocks, which is used for storing a specific type of information.
Data Blocks are the base unit of logical database space. Each data block represents a specific number of bytes of database space on a disk
6) What is an Extent ?
Extent is a collection of Continuous data blocks, which is used for storing a specific type of information.
7)
What is a Segment ?
A segment is a collection of extends which is used for storing a specific data structure and resides in the same tablespace.
8) What is Rollback Segment ?
Database contain one or more Rollback Segments to roll back transactions and data recovery.
9) What are the different type of Segments ?
Data Segment(for storing User Data), Index Segment (for storing index), Rollback Segment and Temporary Segment.
10) What is a Redo Log ?
Redo Log files is a collection of 2 or more pre-allocated files, which is used in data recovery. When ever a change is made to the database, change info gets stored in redo files. In case of a database crash, we can used redo files for data recovery.
11) What is a table Cluster ?
Table Cluster is a group of related tables that share common columns are store related data in the same block.
12) What is a cluster Key ? A segment is a collection of extends which is used for storing a specific data structure and resides in the same tablespace.
8) What is Rollback Segment ?
Database contain one or more Rollback Segments to roll back transactions and data recovery.
9) What are the different type of Segments ?
Data Segment(for storing User Data), Index Segment (for storing index), Rollback Segment and Temporary Segment.
10) What is a Redo Log ?
Redo Log files is a collection of 2 or more pre-allocated files, which is used in data recovery. When ever a change is made to the database, change info gets stored in redo files. In case of a database crash, we can used redo files for data recovery.
11) What is a table Cluster ?
Table Cluster is a group of related tables that share common columns are store related data in the same block.
The common column or group of columns associated with the clustered tables is called cluster Key. Advantage of using cluster key is that the common columns will be stored only once.
13) What is a synonym?
Synonym is the alias name for a table, view, sequence or program unit.
14)
What are the two types of Synonyms?
Two types of Synonyms are Private and Public. A private synonym can be accessed by its owner only, where as the public synonym can be accesses by any DB user.
15) What is System Global Area (SGA) ?
The System Global Area (SGA) is a part of system memory which is allocated to all process belonging to oracle instance. We can allocate memory to SGA by modifying Oracle initialization parameters like shared_pool_size, include db_cache_size and log_buffer.
16) What is a shared pool?
Shared pool is one of the most important part of SGA. Shared pool is used by oracle to handle identical queries, which enables it to execute only once thus by improving performance. Shared Pool depends on db_cache_size parameter.
17) What is Program Global Area (PGA)?
Program Global Area is the non shared memory used by oracle that contain data and control information of server process.
18) What is dictionary cache ?
Oracle Data directory contains meta data about the tables owned by SYSTEM and SYS schema's. Proper sizing of data directory cache allows fast retrieval of data from data dictionary.
19) What is Database Buffer Cache ?
Database buffer cache is used by SGA to hold blocks of data read from data files. Each buffer can hold one database block.
20) What is a cursor ?
When a DML statements like INSERT, UPDATE, DELETE, or MERGE is executed or when SELECT query is executed, the information (statement and the rows of data accessed by it) about the same will be stored in private SQL area. Cursor is a pointer to this private SQL area.
21) Explain the two type of Cursors ?
Two types of cursors are Implicit Cursor and Explicit Cursor. Implicit Cursors are created when SELECT which returns one row, INSERT, UPDATE and DELETE statements are executed. Explicit Cursors are user defined cursors which get created when SELECT statement return more than one row.
22) What is a Query Record Group?
A query record group is a record group that has an associated SELECT statement. Columns in query record group derive their default names, data types, had lengths from the database columns referenced in the SELECT statement. Records in query record group are the rows retrieved by the query associated with that record group.
23) What is row chaining?
When size of a row exceed size of data block, data for the row is stored in a chain of data block reserved for that segment. This is called row chaining
Two types of Synonyms are Private and Public. A private synonym can be accessed by its owner only, where as the public synonym can be accesses by any DB user.
15) What is System Global Area (SGA) ?
The System Global Area (SGA) is a part of system memory which is allocated to all process belonging to oracle instance. We can allocate memory to SGA by modifying Oracle initialization parameters like shared_pool_size, include db_cache_size and log_buffer.
16) What is a shared pool?
Shared pool is one of the most important part of SGA. Shared pool is used by oracle to handle identical queries, which enables it to execute only once thus by improving performance. Shared Pool depends on db_cache_size parameter.
17) What is Program Global Area (PGA)?
Program Global Area is the non shared memory used by oracle that contain data and control information of server process.
18) What is dictionary cache ?
Oracle Data directory contains meta data about the tables owned by SYSTEM and SYS schema's. Proper sizing of data directory cache allows fast retrieval of data from data dictionary.
19) What is Database Buffer Cache ?
Database buffer cache is used by SGA to hold blocks of data read from data files. Each buffer can hold one database block.
20) What is a cursor ?
When a DML statements like INSERT, UPDATE, DELETE, or MERGE is executed or when SELECT query is executed, the information (statement and the rows of data accessed by it) about the same will be stored in private SQL area. Cursor is a pointer to this private SQL area.
21) Explain the two type of Cursors ?
Two types of cursors are Implicit Cursor and Explicit Cursor. Implicit Cursors are created when SELECT which returns one row, INSERT, UPDATE and DELETE statements are executed. Explicit Cursors are user defined cursors which get created when SELECT statement return more than one row.
22) What is a Query Record Group?
A query record group is a record group that has an associated SELECT statement. Columns in query record group derive their default names, data types, had lengths from the database columns referenced in the SELECT statement. Records in query record group are the rows retrieved by the query associated with that record group.
23) What is row chaining?
When size of a row exceed size of data block, data for the row is stored in a chain of data block reserved for that segment. This is called row chaining
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