There may be empty space in a block if an integral number of records do not fit in one block.

bfr refers to the number of records per disk.

Refers to records that exceed the size of one or more blocks and hence span a number of blocks.

is a sequence of records

includes information that describes the file

Blocking factor is the (average) number of file records stored in a disk block.

A file can have fixed-length records or variable-length records.

File records can not be unspanned or spanned

no record can span two blocks

Spanned: a record can be stored in more than one block

ordered Files called a heap or a pile file.

ordered Files called:

New records are inserted at the end of the file in Unordered Files

Record insertion is quite efficient in Ordered Files .

Reading the records in order of a particular field requires sorting the file records

Unordered Files Also called a sequential file

File records are kept sorted by the values of an ordering field.

Insertion is not expensive: records must be inserted in the correct order.

A binary search can not be used to search for a record on its ordering field value.

Reading the records in order of the ordering field is not quite efficient.

Hashing for disk files is called Internal Hashing