Compressed table features in MySQL database

The compressed storage format is a read-only format created by the Myisampack tool.

All MySQL distributions include myisampack by default. Compressed tables can be decompressed using MYISAMCHK.

A compressed table has the following characteristics:

· Compressed tables occupy very small disk space. This minimizes the amount of disk used, which is useful when using slow disks such as CD-ROM.

· Each record is compressed individually, so only very small access expenses are available. The header of a record occupies 1 to 3 bytes per table, depending on the largest record in the table. Each column is compressed differently. Usually each column has a different Huffman tree. Some of the compression types are as follows:

o suffix space compression.

-Prefix space compression.

-the number of 0 values is stored with a bit.

-If the value in an integer column has a small range, the column is stored with the smallest possible type. For example, a bigint column (8 bytes), if all its values are within the range of 128 to 127, it can be stored as a tinyint column (1 bytes)

-If a column has only a small set of possible values, the column type is converted to an enum.

-A column can use any merge of the previous compression type.

· You can handle fixed-length or dynamic-length records.