Flat file database

A flat file database is one in which data is stored in plain text format. It is usually used to store and retrieve a small amount of data in a local text file.

Need of flat file database:

Most free web host do not allow their users to use MYSQL database for free. In that case flat file database is an alternative solution.

How to store data:

In a database data are stored in tabulated form. An example of typical table database is given below.

Name	Class	Age
John	9	15
Susan	6	11
Emili	10	15

When we store such a table in a flat file database file structure will be as follows.

John^^9^^15
Susan^^6^^11
Emili^^10^^15

Here I use a new string "^^" as column separator, and new line character is used for row separation. While selecting such a separator we must confirm that data itself not contain that string. So we have to filter-out data from such string before any write operation.

Problems of flat file database:

1. A flat file is a SISO (serial in serial out) memory system. New data can only be entered at the end of the file. So if we want to edit or delete a record from our database; or if we want to insert a new record in-between two records, we have to rearrange and then rewrite the entire database file. So speed of operation lowers with the size of database file. Actually flat file database should not be used for size more than 5mb.

2. Flat file database is not very safe in multi-user environment like blog, guestbook etc. where many users sharing the same database from different ends.