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Lesson 7Table Partitioning
ObjectiveExplain the purpose of Partitioning

Database Table Partitioning

Clustering brings records from two or more tables together on a hard disk to improve joins between the two tables. Partitioning a table, by contrast, splits a single table into two or more tables to limit the amount of data the RDBMS has to retrieve at once. There are two types of partitioning operations:
  1. Horizontal partitioning, which splits a table's records into two or more tables
  2. Vertical partitioning, which splits a table's columns into two or more tables

The best way to remember how each type of partitioning divides a table is to envision drawing a line across a table. If you draw a horizontal line, the table's records are split into two identical tables.

Horizontal partitioning
Horizontal partitioning


Drawing a vertical line splits the table's columns into two tables, which must then be linked by the table's primary key columns.

Vertical partitioning
Vertical partitioning

The following lessons explain the advantages and disadvantages of both partitioning methods.
The next lesson introduces horizontal partitioning.