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Recovery of cloned objects

NGT Recover supports the recovery of cloned tables.

Use the CLONE option on the following NGT Recover commands to recover with clone objects:

  • RECOVER

  • REBUILD

  • RECOVER UNLOADKEYS

  • RECOVER BUILDINDEX

  • LOGSCAN

When you are creating an output copy or a model DCB, you can use the symbolic variable &INST for the instance number (see the table in, Using symbolic variables). Valid values are 1 and 2.

A clone table is a table with the exact same attributes as an existing table, which is called the base table. The clone is created in the same table space as the base table, is structurally identical to the base table in every way and has the same indexes, triggers, and LOB objects. You can only create clone tables in a universal table space that is managed by DB2.

The base and clone table data and their index data reside in different data sets. For example:

  • catName.DSNDBx.dbName.psName.x0001.A001

    This data set contains instance number 1 (the 1 of x0001).

  • catName.DSNDBx.dbName.psName.x0002.A001

    This data set contains instance number 2 (the 2 of x0001).

DB2 handles log records and log ranges for both base and clone table objects. The base and clone objects are differentiated by differences in the PSID value. The high order bit of the PSID is used to refer to a particular data set instance number as follows:

  • A high order bit value of 0 indicates instance number 1

  • A high order bit value of 1 indicates instance number 2

Other than the high order bit, the PSID numbers are the same for both a base object and its clone.

NGT Recover support for clone objects includes the following limitations:

  • You cannot specify the same object with and without the CLONE option in the same SYSIN data set.

    NGT Recover issues an error message if you specify a recovery command for the base and clone instance of the same object in the same SYSIN data set.

  • All related objects (indexes and underlying table space, LOB objects) should have the same CLONE specification in the same step.

    NGT Recover issues an error message if the CLONE specification does not match for the related objects.

  • You cannot recover a clone or base object to a point prior to the last EXCHANGE statement.

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