Tables are logical structures maintained by the database manager. Tables are made up of columns and rows. There is no inherent order of the rows within a table. At the intersection of every column and row is a specific data item called a value. A column is a set of values of the same type. A row is a sequence of values such that the nth value is a value of the nth column of the table.
There are three types of tables:
A base table has a name and may have a different system name. The system name is the name used by i5/OS. Either name is acceptable wherever a table-name is specified in SQL statements.
A column of a base table has a name and may have a different system column name. The system column name is the name used by i5/OS. Either name is acceptable wherever column-name is specified in SQL statements. For more information see CREATE TABLE.
A materialized query table is used to contain materialized data that is derived from one or more source tables specified by a select-statement. A source table is a base table, view, table expression, or user-defined table function. The select-statement specifies the query that is used to refresh the data in the materialized query table.
A partitioned table is a table whose data is contained in one or more local partitions (members). There are two mechanisms that can be specified to determine into which partition a specific row will be inserted. Range partitioning allows a user to specify different ranges of values for each partition. When a row is inserted, the values specified in the row are compared to the specified ranges to determine which partition is appropriate. Hash partitioning allows a user to specify a partitioning key on which a hash algorithm is used to determine which partition is appropriate. The partitioning key is a set of one or more columns in a partitioned table that are used to determine in which partition a row belongs.
A distributed table is a table whose data is partitioned across a nodegroup. A nodegroup is an object that provides a logical grouping of a set of two or more systems. The partitioning key is a set of one or more columns in a distributed table that are used to determine on which system a row belongs. For more information about distributed tables, see the DB2(R) Multisystem book.
(C) Copyright IBM Corporation 1992, 2006. All Rights Reserved.