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Transformation with the High-speed Structure Change process

The High-speed Structure Change process includes the following methods:

  • SHRLEVEL REFERENCE

    The SHRLEVEL REFERENCE parameter enables other applications to have read-only access during the transformation.

  • SHRLEVEL CHANGE

    The SHRLEVEL CHANGE parameter enables other applications to have read-write access during the transformation by using Online Consistent Copies, Log Master, and the High-speed Apply Engine.

Related topic

High-speed-Structure-Change


Important

Because the SHRLEVEL CHANGE method uses Online Consistent Copies, you need to have access to a Recovery Management for Db2 password for this method.

Each method provides more availability and uses less CPU resources than the steps in Transformation-without-the-High-speed-Structure-Change-process.

The transformation is done using a shadow object. This object is referred to as the target object. The object that you want to transform is referred to as the source object. The target object is identical to the source object, except for one or more of the following attributes:

Table spaces

  • DSSIZE
  • SEGSIZE
  • MAXPARTITIONS
  • MEMBER CLUSTER
  • BUFFERPOOL (target page size must be larger than source)

Index spaces

  • PIECESIZE
  • BUFFERPOOL (target page size must be larger than source)
  • COMPRESS

If the row formats are different, the target catalog is updated with the row format of the source image. Other attributes, such as PRIQTY, SECQTY, PCTFREE, and FREEPAGE, may be different, but they are not honored until you perform a REORG.

The High-speed Structure Change process works at the page level and uses an Online Consistent Copy or Instant Snapshot of the source as input reads each page and transforms the page to fit the new definition. The High-speed Structure Change process then moves the page to the target data set.

Transforming your objects is a non-destructive process. Your source object is not touched. You can use your source object for fallback if for some reason you are not happy with the transformation. You can also create an image copy of your target table space, which eliminates the need to image copy the new table space after the transformation. The image copy is an inline image copy.

Important

Recovering with this type of image copy is not as efficient as with a typical image copy. Creating a SHRLEVEL CHANGE image copy or an Online Consistent Copy after the transformation has been completed might be a better strategy.

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