How many different types of indexes we have in oracle?
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Answer / sathish
B TREE INDEX
FUNCTION BASED INDEX
REVERSE KEY INDEX
BIT MAP INDEX
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Answer / rohit
In Oracle there are two types of SQL index namely, implicit and explicit.
Implicit Indexes:
They are created when a column is explicity defined with PRIMARY KEY, UNIQUE KEY Constraint.
Explicit Indexes:
They are created using the "create index.. " syntax.
NOTE:
1) Even though sql indexes are created to access the rows in the table quickly, they slow down DML operations like INSERT, UPDATE, DELETE on the table, because the indexes and tables both are updated along when a DML operation is performed. So use indexes only on columns which are used to search the table frequently.
2) Is is not required to create indexes on table which have less data.
3) In oracle database you can define up to sixteen (16) columns in an INDEX.
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Answer / shankar
1.B-tree indexes:
B-tree indexes have the following subtypes:
Index-organized tables
Reverse key indexes
Descending indexes
B-tree cluster indexes
2.Bitmap and bitmap join indexes
3.Function-based indexes
4.Application domain indexes
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