Data base is a collection of files,each files is a collection of records,each record is a sequence of fields.

Blocking factor:

blocking factor is the avg no of records per block.

There are some strategies for storing file of record into block and they are as follows:

1)Spanned Strategy:

It allows partial part of record that can be stored in a block.It is suitable for variable length record.

some time we try to fatch the web page and put them as a record in a database and every webpage may have different sizes in that cas we use spanned stratergy.

Advantages: No wastage of memory

Disadvantage:Block access increases

2)UnSpanned Straregy:

no record can be stored in more than 1 block.It is suitable for fixed  length record.

If company record has eemploee data base that are fixed size ,in such case we go for un spanning.

Advantage: block access reduced

Disadvantage: wastage of memory