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<h1 class="topictitle1">Partitioned tables</h1>
<div><p>DB2<sup>®</sup> UDB
for iSeries™ supports
partitioned tables using SQL.</p>
<p>Partitioning allows for the data to be stored in more than one member,
but the table appears as one object for data manipulation operations, such
as queries, inserts, updates, and deletes. The partitions inherit the design
characteristics of the table on which they are based, including the column
names and types, constraints, and triggers.</p>
<p>Partitioning allows you to have much more data in your tables. Without
partitioning, there is a maximum of 4 294 967 288 rows in a table,
or a maximum size of 1.7 terabytes. A partitioned table, however, can have
many partitions, with each partition able to have the maximum table size.
For more information about maximum size for partitioned tables, refer to the DB2 UDB
for iSeries White
Papers.</p>
<p>Partitioning can also enhance the performance, recoverability, and manageability
of your database. Each partition can be saved, restored, exported from, imported
to, dropped, or reorganized independently of the other partitions. Additionally,
partitioning allows for quickly deleting sets of records grouped in a partition,
rather than processing individual rows of a nonpartitioned table. Dropping
a partition provides significantly better performance than deleting the same
rows from a nonpartitioned table.</p>
<p>A partitioned table created on an iSeries server is a database file with
multiple members. A partition is the equivalent of a database file member.
Therefore, most of the CL commands that are used for members are also valid
for each partition of a partitioned table.</p>
<p>You must have DB2 Multisystem installed on your iSeries server in order to take advantage
of partitioned tables support. There are, however, some important differences
between DB2 Multisystem
and partitioning. DB2 Multisystem provides two ways to partition your data:</p>
<ul><li>You can create a distributed table to distribute your data across several iSeries systems
or logical partitions.</li>
<li>You can create a partitioned table to partition your data into several
members in the same database table on one system.</li>
</ul>
<p>In both cases, you access the table as if it were not partitioned at all.</p>
</div>
<div>
<ul class="ullinks">
<li class="ulchildlink"><strong><a href="creatept.htm">Creation of partitioned tables</a></strong><br />
New partitioned tables can be created using the <samp class="codeph">CREATE
TABLE</samp> statement.</li>
<li class="ulchildlink"><strong><a href="alterpt.htm">Modification of existing tables</a></strong><br />
You can change existing nonpartitioned tables to partitioned tables, change the attributes of existing partitioned tables, or change partitioned table to nonpartitioned tables.</li>
<li class="ulchildlink"><strong><a href="indexpt.htm">Indexes with partitioned tables</a></strong><br />
Indexes can be created as partitioned or nonpartitioned. A partitioned index creates an individual index for each partition. A nonpartitioned index is a single index spanning all partitions of the table.</li>
<li class="ulchildlink"><strong><a href="performancept.htm">Query performance and optimization</a></strong><br />
Queries that reference partitioned tables need to be carefully considered because partitioned tables are often very large. It is important to understand the effects of accessing multiple partitions on your system and applications.</li>
<li class="ulchildlink"><strong><a href="partsave.htm">Save and restore considerations</a></strong><br />
A partitioned table can be saved and restored just as any other database file.</li>
<li class="ulchildlink"><strong><a href="partjournal.htm">Journaling</a></strong><br />
You can journal a partitioned table as you can journal any other database file with multiple members. When you journal a partitioned table, all the partitions of the table are journaled by the same journal.</li>
<li class="ulchildlink"><strong><a href="partnative.htm">Native interface considerations</a></strong><br />
An SQL table is a database physical file with one member (partition). Therefore, when the file is accessed by a native application, the native application reads and writes to the member by opening the file's member.</li>
<li class="ulchildlink"><strong><a href="partrestrict.htm">Restrictions</a></strong><br />
There are some restrictions for a partitioned table.</li>
</ul>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaf3kickoff.htm" title="This topic describes the fundamental concepts of DB2 Multisystem, such as distributed relational database files, node groups, and partitioning, and provides the information necessary to create and to use database files that are partitioned across multiple iSeries servers. Information is provided on how to configure the systems, how to create the files, and how the files can be used in applications. This topic also describes table partitioning. Table partitioning varies from multisystem partitioning in that it is a table partitioned on a single server.">DB2 Multisystem</a></div>
</div>
<div class="relconcepts"><strong>Related concepts</strong><br />
<div><a href="basicterms.htm" title="A distributed file is a database file that is spread across multiple iSeries servers. This section describes some of the main concepts that are used in discussing the creation and use of distributed files by DB2 Multisystem.">DB2 Multisystem: Basic terms and concepts</a></div>
</div>
<div class="relinfo"><strong>Related information</strong><br />
<div><a href="http://www-1.ibm.com/servers/eserver/iseries/db2/db2awp_m.htm">DB2 UDB for iSeries white papers</a></div>
</div>
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