IAMSRORG — IAM special reorganization process

IAMSRORG uses a variety of techniques to enhance the reorganization process performance resulting in a reduction of time that a data set is unavailable for processing. IAMSRORG utilizes an IAM data set reorganization process that copies data from an input IAM data set, and writes directly into an output IAM data set, without reading the index from the source data set. The program will read through the extended overflow blocks passing the records to the system SORT program to sort the overflow records in ascending key sequence.

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IAM-enhanced-data-set-reorganization

 On the output side it will merge the sorted overflow records with the already in sequence prime data records and write those records to the output data set. This process is invoked by the Dynamic Reorganization IAMDRCC program to create the reorganized copy of the IAM data set as described in the prior sections. The process can also be used as a separate batch utility program to do a high-performance reorganization of IAM files reducing the time that the IAM data set is not available compared to other reorganization techniques.

An optional sequential output data set can be produced that is a portable copy of the data set which can be z/EDC compressed. That portable copy of the data set contains additional information about the data set, including all of the information necessary to define the data set as part of an IMPORT process. If the original data set contained compressed data, then the portable copy will also have the compressed data. If the original data set was hardware compressed, the portable copy will contain the hardware compression dictionary needed to decompress and compress data for that IAM data set. The exported output data set can only be utilized by the IAMSRORG IMPORT function to restore the data set to it’s original content. For a sequential copy of only the data in the file as the backup output from the REORG, then specification of the NOEXPORT keyword on the REORG command will produce such a copy that can be used by applications and REPRO to process the uncompressed data records that will be in ascending key sequence.

The functions provided by IAMSRORG are:

  • REORG—Reorganize the input IAM data set directly into another IAM data set. The output IAM data set will be a reorganized data set with no overflow records. An optional sequential portable copy of the data can also be created.
  • EXPORT—Create a portable copy of the input IAM data set.
  • IMPORT—Create an IAM data set from the portable copy created by the REORG or EXPORT command. Has the capability to define the output IAM data set with all of the original data set attributes.

 

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