Allocate Extent

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The Allocate Extent dialog lets you explicitly allocate extents for clusters, tables, and indexes in Oracle. Though Oracle dynamically allocates extents when additional space is required, explicit allocation of additional extents can be useful if you know that an object grows.

Explicit allocation of additional extents can be particularly helpful when using Oracle Parallel Server. When using Oracle Parallel Server and allocating additional extents, you can allocate an extent explicitly to a specific instance in order to minimize contention for free space among multiple instances.

Platform Availability

• ORCL

Important Notes

For composite-partitioned tables, you can allocate extents to subpartitions as well as partitions.

To Allocate an Extent for a Cluster, Table, or Index

1. Initiate an Allocate Extent action against a table, cluster, index, primary key, or unique key. For more information see Initiating an object operation.
2. Use the following table as a guide to setting the options on this dialog:

Option	Description
Extent Size	Specify an extent size in KBs or MBs.
Datafile	Lets you select the new datafile. You can choose a specific datafile from which to take space for the added extent. If you choose (Default), Oracle takes the space from any accessible datafile in the tablespace containing the table, index, or cluster.
Instance	Lets you specify a freelist from which to draw the extent. If you are using Oracle Parallel Server, you can assign the new extent to a free list group associated with a specific instance. The number you enter in the Instance text box should be the number of the freelist group that you wish to use, rather than the number of the specific instance. If you are using Oracle Parallel Server and you omit this parameter, Oracle allocates the extent, but the extent is drawn from the master freelist by default. Only use this parameter for Oracle Parallel Server. NOTE: The number you enter in the Instance field should be the number of the free list group that you wish to use, rather than the number of the specific instance.

3. Click Execute. For information on the scheduling option, see Scheduling.