Question

Why you need to have multiple indexing schemes if you want to search through a database based on different keys?

Answer 1

ANSWER :-

Indexing: Indexing is a data structure technique to efficiently retrieve records from the database files based on some attributes on which the indexing has been done. Indexing in database systems is similar to what we see in books.

Multiple Indexing Schemes

Data block 0 Index Block 0 Data block 1 Index Block 1 outer index Data block 2 Inner index Data block 3

"Multiple indexing schemes improves the performance of searching for a record based on a specified indexing field value."

• Multiple indexing is created when a primary index does not fit in memory. In this type of indexing method, you can reduce the number of disk accesses to short any record and kept on a disk as a sequential file and create a sparse base on that file.

• Index records comprise search-key values and data pointers. Multiple index is stored on the disk along with the actual database files. As the size of the database grows, so does the size of the indices. There is an immense need to keep the index records in the main memory so as to speed up the search operations. If single-level index is used, then a large size index cannot be kept in memory which leads to multiple disk accesses.

• Multiple Index helps in breaking down the index into several smaller indices in order to make the outermost level so small that it can be saved in a single disk block, which can easily be accommodated anywhere in the main memory.