What Is Dictionary Cache?
Dictionary cache is information about the database objects stored in a data dictionary table.
What Is Database Buffers?
Database buffers are cache in the SGA used to hold the data blocks that are read from the data segments in the database such as tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the size.
What Are The Factors Causing The Reparsing Of Sql Statements In Sga?
Due to insufficient shared pool size.
Monitor the ratio of the reloads takes place while executing SQL statements. If the ratio is greater than 1 then increase the SHARED_POOL_SIZE.
Database Logical & Physical Architecture
What Is A Data Segment?
Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.
What Are Disadvantages Of Having Raw Devices?
We should depend on export/import utility for backup/recovery (fully reliable)
The tar command cannot be used for physical file backup, instead we can use dd command, which is less flexible and has limited recoveries.
When Will Be A Segment Released?
When Segment is dropped.
When Shrink (RBS only)
When truncated (TRUNCATE used with drop storage option)
How Will You Monitor The Space Allocation?
By querying DBA_SEGMENT table/view
What Are The Advantages Of Views?
Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
Hide data complexity.
Simplify commands for the user.
Present the data in a different perspective from that of the base table.
Store complex queries.
Can A View Based On Another View?
Yes.
Do A View Contain Data?
Views do not contain or store data.
What Is An Oracle View?
A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What Is Oracle Table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
Can A Tablespace Hold Objects From Different Schemes?
Yes.
Can Objects Of The Same Schema Reside In Different Tablespaces?
Yes.
What Are Schema Objects?
Schema objects are the logical structures that directly refer to the database’s data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.
What Is Schema?
A schema is collection of database objects of a user.
Explain The Relationship Among Database, Tablespace And Data File.
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
Why Query Fails Sometimes?
Rollback segment dynamically extent to handle larger transactions entry loads.
A single transaction may wipeout all available free space in the rollback segment tablespace. This prevents other user using rollback segments.
How The Space Utilization Takes Place Within Rollback Segments?
It will try to fit the transaction in a cyclic fashion to all existing extents. Once it found an extent is in use then it forced to acquire a new extent (number of extents is based on the optimal size)
How Will You Create Multiple Rollback Segments In A Database?
- Create a database, which implicitly creates a SYSTEM rollback segment in a SYSTEM tablespace.
- Create a second rollback segment name R0 in the SYSTEM tablespace.
- Make new rollback segment available (after shutdown, modify init.ora file and start database)
- Create other tablespaces (RBS) for rollback segments.
- Deactivate rollback segment R0 and activate the newly created rollback segments.
What Is The Functionality Of System Table Space?
To manage the database level transactions such as modifications of the data dictionary table that record information about the free space usage.
Dictionary cache is information about the database objects stored in a data dictionary table.
What Is Database Buffers?
Database buffers are cache in the SGA used to hold the data blocks that are read from the data segments in the database such as tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the size.
What Are The Factors Causing The Reparsing Of Sql Statements In Sga?
Due to insufficient shared pool size.
Monitor the ratio of the reloads takes place while executing SQL statements. If the ratio is greater than 1 then increase the SHARED_POOL_SIZE.
Database Logical & Physical Architecture
What Is A Data Segment?
Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.
What Are Disadvantages Of Having Raw Devices?
We should depend on export/import utility for backup/recovery (fully reliable)
The tar command cannot be used for physical file backup, instead we can use dd command, which is less flexible and has limited recoveries.
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When Will Be A Segment Released?
When Segment is dropped.
When Shrink (RBS only)
When truncated (TRUNCATE used with drop storage option)
By querying DBA_SEGMENT table/view
What Are The Advantages Of Views?
Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
Hide data complexity.
Simplify commands for the user.
Present the data in a different perspective from that of the base table.
Store complex queries.
Can A View Based On Another View?
Yes.
Do A View Contain Data?
Views do not contain or store data.
What Is An Oracle View?
A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
What Is Oracle Table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
Can A Tablespace Hold Objects From Different Schemes?
Yes.
Can Objects Of The Same Schema Reside In Different Tablespaces?
Yes.
What Are Schema Objects?
Schema objects are the logical structures that directly refer to the database’s data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.
What Is Schema?
A schema is collection of database objects of a user.
Explain The Relationship Among Database, Tablespace And Data File.
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
Rollback segment dynamically extent to handle larger transactions entry loads.
A single transaction may wipeout all available free space in the rollback segment tablespace. This prevents other user using rollback segments.
How The Space Utilization Takes Place Within Rollback Segments?
It will try to fit the transaction in a cyclic fashion to all existing extents. Once it found an extent is in use then it forced to acquire a new extent (number of extents is based on the optimal size)
How Will You Create Multiple Rollback Segments In A Database?
- Create a database, which implicitly creates a SYSTEM rollback segment in a SYSTEM tablespace.
- Create a second rollback segment name R0 in the SYSTEM tablespace.
- Make new rollback segment available (after shutdown, modify init.ora file and start database)
- Create other tablespaces (RBS) for rollback segments.
- Deactivate rollback segment R0 and activate the newly created rollback segments.
What Is The Functionality Of System Table Space?
To manage the database level transactions such as modifications of the data dictionary table that record information about the free space usage.
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