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What is Alternate Index ? How is it different from regular
index ?
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Answer / vish
The answer provided by NK is absolutely correct but we
should be very careful whil choosing the alternate index as
it may not be Unique. e.g. in the example given by NK, the
Emp# will always be Unique within a company but many many
employees can have the same name. So if we declare Emp_name
as AIX (i.e. alternate Index) and then use it for fetching
data then we may end up in multiple rows and hence we may
need additonal logic to arrive at the desired unique record.
Your comments are Welcome!!
| Is This Answer Correct ? | 14 Yes | 0 No |
Answer / nk
The purpose of any index is to provide the most efficient
access to the records in a file. Say you have a file of
employee names and numbers. Usually the primary index will
be the employee number. If you request a record by
providing the empl#, the access will be very fast. If you
have to very often request a record by the empl name, you
may want to create a second (a/k/a alternate) index based
on the name. So when you provide a name, the access to the
correct record also will be very fast.
| Is This Answer Correct ? | 10 Yes | 2 No |
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