PARTITIONING “ A de-normalization practice in which relations are split instead of merger ”

TYPES OF PARTITIONING:- Partitioning is of two types. (1) Horizontal Partitioning. (2) Vertical Partitioning.

Horizontal Partitioning. - Distributing the rows of a table into several separate files. - Breaks a relation into multiple record specifications by placing different rows into different records based upon common column values.

Examples of horizontal Partitioning. In a library setting, horizontal partitioning is similar to placing the business journals in a business library, the science books in a science library.

Vertical Partitioning Distributing the columns of “ a table into several separate physical records. Distributes the columns of a relation into separate physical records, repeating the primary key in each of the records.

Example of vertical Partitioning An example of vertical partitioning Would be braking apart a part relation by placing the part no. alone with accounting – related part data in to another record specification, the part no along with engineering- related part data into another record specification and the part no along with sales-related part data into another record specification.

Need for Partitioning.

Advantages and Disadvantages Advantages of Partitioning:- 1) Efficiency: Data used together are stored close to one another and separate from data not used together. 2) Local Optimization: Each partition of data can be stored to optimize performance for its own use. 3) Security: Data not relevant to one group of users can be segregated from data they are allow to use. 4) Recovery and Uptime: Smaller size will take less time to recover, and other files are still accessible if one file is damaged, so the effects of damage are isolated. 5) Load Balancing: Files can be allocated to different storage area ( Disk or another Media), which minimizes contentions for access to the same storage area OR even allows for parallel access to different areas.

Disadvantages of Partitions. 1) Inconsistent access speed : Different partition may yield difference access speeds thus confusing users. 2) Complexity: Partitioning is usually not transparent to programmers, who will have to write more complex programs when combining data across partitions. 3) Extra space and update time: Data may be duplicated across the partition, taking extra storage space compare to storing all the data in normalized files. Updates which affects data in multiple partitions can take more time than if one file were used.