Oracle Interview Question and Answers
41. |
What is an Oracle index? |
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An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table. |
42. |
What are the different index configurations a table can have? |
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- A table can have one of the following index configurations
- No indexes
- A clustered index
- A clustered index and many nonclustered indexes
- A nonclustered index
- Many nonclustered indexes.
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43. |
What is difference between UNIQUE constraint and PRIMARY KEY constraint? |
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A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls. A table can have only one primary keys. |
44. |
What is BCP? When does it used? |
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BulkCopy is a tool used to copy huge amount of data from tables and views. BCP does not copy the structures same as source to destination. |
45. |
How to know which index a table is using? |
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SELECT table_name,index_name FROM user_constraints. |
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