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