what are indexes..how many types of index's are there and
what are they?
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Answer Posted / rudrab123
Answer 1 is not he basic function of Index in Oracle or any
databse.
Generally speaking,attaching index to a column in a table,
information of the location of the different values in the
indexed column is also provided.This address is like the
pointer varible in C,and in SQL it is called ROWID(a
pseudocolumn).Let us see he example ....
SQL>select * from students
where id=123;
Students is a databse table and ID is the column in the
table on which we create the index.
On execution of the above query, at first, the ROWID
corresponding to id=123 in students table is found.From
this rowid, the index value for the row of data which is
pointed to by ROWID is found(in very less time).And so the
row is idenified and the entire row data is displayed.
The above serach process is specifically called "TABLE
ACCESS FULL(USING ROWID)).
| Is This Answer Correct ? | 3 Yes | 2 No |
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