Copying compressed indexes

Db2 Version 9 introduced compression for indexes. BMC AMI Copy provides native support for copying compressed indexes

To copy compressed indexes

Use one of the following methods:

• Make copies of the compressed indexes

  BMC AMI Copy makes copies of the compressed indexes without expanding them. BMC AMI Copy registers these copies in the BMCXCOPY table. This method has the advantages that making the copies is faster and the copies are smaller than when copies are made of expanded indexes. Also, all BMC AMI Copy copy techniques, such as Instant Snapshots, online consistent copies, encrypted copies, and cabinet copies, are supported.

  The restrictions of this method are that the copy is not compatible with the Db2 utilities and the BMC AMI Recover product is required to use these copies for recovery.

• Emulate the IBM Db2 COPY utility

  BMC AMI Copy reads the compressed indexes directly from disk and expands them before writing the image copy. This method has the advantages that BMC AMI Copy registers the copy in SYSCOPY and the copy is compatible with those produced by the IBM Db2 COPY utility.

  Some disadvantages of this method are that it takes time to expand the pages and the resulting image copies are larger than necessary. Also, BMC AMI Copy copy techniques, such as Instant Snapshot copies and online consistent copies, are not supported.

The IXEXPAND installation option (IXEXPAND = AUTO) indicates which method you want to use. Valid values are AUTO, YES, and NO. You can override the installation option by using the IXEXPAND option on the OPTIONS command (OPTIONS-syntax-option-description).

The default value for IXEXPAND is AUTO, in which case, BMC AMI Copy checks to see if you are using a Recovery Management for Db2 password. If you are running Recovery Management for Db2, BMC AMI Copy makes copies of compressed indexes in their unexpanded format, which is the equivalent of setting IXEXPAND to NO. If you are not running Recovery Management for Db2, BMC AMI Copy expands the compressed indexes before making the copy, which is the equivalent of setting IXEXPAND to YES.

If you are performing a Db2 catalog copy and you are running under a Recovery Management for Db2 password, you should set IXEXPAND=YES to prevent an error caused by IXEXPAND=AUTO (the default value) converting to IXEXPAND=NO. For copies of DSNDB01 and DNSDB06, an IXEXPAND=AUTO setting converts to IXEXPAND=YES.

You can override the IXEXPAND installation option value at runtime by specifying the IXEXPAND option on the OPTIONS command.

If you specify IXEXPAND YES and request a copy that BMC AMI Copy cannot decompress, such as an Instant Snapshot, BMC AMI Copy makes a compressed copy and issues an informational message.