**File organization:** It is ****the logical relation between records and it defines how file records are mapped into disk blocks(memory). A database is a collection of files, each file is a collection of records, and each record contains a sequence of fields. The blocking Factor is the average number of records per block.

Strategies for storing files of records in block:

• Spanned Strategy: It allows a partial part of the record to be stored in the block. It is suitable for variable-length records. No wastage of memory in spanned strategy but block access time gets increases.
• Unspanned Strategy:  Data cannot be stored partially, the whole block will be occupied, this can lead to internal fragmentation and wastage of memory but block access time is reduced. This is suitable for fixed-length records.

File organizations is of following types:

• Sequential File Organization
• Heap File Organization
• Hash File Organization
• B+ Tree File Organization
• Clustered File Organization

Sequential File: In this method, files are stored in sequential order one after another.

• Blocking factor:

  

• Number of record blocks:

  

• Average number of blocks accessed by linear search:

  

• Average number of blocks accessed by binary search:

  

Index File:

• Index blocking factor:

  

• First level index block:

  

• Number of block accesses: