Functions of the Reorganization Steps

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Functions of the Reorganization Steps

The table below shows how the reorganization steps can be grouped together by function. The table gives you a clear picture of which steps perform the allocation and update functions and which steps access the old database and the new database, or both.

ANALYSIS (Analysis) Step--CA IDMS/DB Reorg compares the old subschema and DMCL to the new subschema and DMCL (all are named in the PROCESS statement) and determines how to process records that have set linkage with the COPY areas.
OPTALLOC (Optimum Allocation/Pointer Extract) Step-- Determines the optimum target page allocation for every record in the areas to be reorganized. Processing in OPTALLOC allocates records to pages as if a page could hold every record that targeted to that page. CA IDMS/DB Reorg then creates pointer extracts for set linkages with records in the areas selected by using the COPY statement.
If a record is indexed and the index is maintained in db-key sequence, the extract is flagged for later special processing by the MATCH step and the IIXSDBK step.
PRIALLOC (Primary Allocation) Step--Allocates a record's real db-key (based on the user-specified priority in the PRIORITY parameter) for records stored DIRECT and CALC. For VIA records, CA IDMS/DB Reorg allocates the db-key for records that target to the owner page. DIRECT, CALC and VIA records that will not fit on the target page are written to the UNALLOC (unallocated) file.
SECALLOC (Secondary Allocation) Step--Allocates real db-keys for VIA records that do not target to the owner page, and for records that were written to the UNALLOC file. For variable length records that cannot fit as a whole on any page in that record's page range, the SECALLOC Step assigns db-keys to record fragments.
If an integrated index (SR8) resides in an area being copied, the program:
- Reconstructs the integrated index
- Allocates real db-keys for the new SR8 records
- Creates the appropriate pointer extracts for set linkage with records in the copy area
MATCH (Match) Step--Matches the db-keys from the previous two allocation steps (PRIALLOC and SECALLOC) with pointer extracts created in the OPTALLOC Step. The db-keys in the pointer extracts are then updated with the new db-keys from the allocation steps.
This step also creates a separate file for integrated index sets sorted by db-key. The file contains two records for each lower level SR8 record and one record for each upper level SR8 record.

The first lower level records identifies the new db-key. The second lower level record contains a sequence number that identifies the entry's relative position among the duplicates that have the same db-key key. If there are any upper level records that point to lower level duplicates, a record is created that contains the same sequence number as the lower level record to which it points.

Reorganization Steps and Their Functions:

Step/Function	Allocates Records to Area Specified in COPY Statement	Updates Set Linkage	Accesses Old Database	Access New Database
OPTALLOC Step	Computes optimum target page.	Extracts pointers which will change. If copying area with IIX set, writes individual bottom level entries to SECOPTA.	Reads records being copied and those with set linkage.
PRIALLOC Step	Allocates DIRECT, CALC, and VIAs stored on owner's page.
SECALLOC Step	Allocates CALC, DIRECT, VIA overflows, fragments, VIAs not stored on owner's page and SR8 records. Rebuilds IIX tables to create new SR8 structures.	Extracts pointers for all SR8 set linkage.
MATCH Step	Replaces old db-key in pointer extracts with new db-keys from allocations.	Replaces old db-key in pointer extracts with new db-keys from allocations.
IIXSDBK Step	Reorders IIX set sorted by db-key into proper sequence of db-key.	Reorders IIX set sorted by db-key into proper sequence of db-key.
UPDLINK Step		Updates pointer prefix or IXDET table entry with new db-key.	Modifies records with set linkage in non-copy areas. Extracts all records residing in copy areas. Creates the DBREC file and optionally creates the DBKEYS file.
STORE Step				Populates areas being copied.

IIXSDBK--Reorders duplicate SR8 entries that may have been put out of their proper sequence (indexed record db-key) when CA IDMS/DB Reorg assigned new db-keys to the indexed records (during the PRIALLOC or SECALLOC steps).
The IIXSDBK step is executed only if you have COPYed an area containing an integrated index set sorted by db-key. Otherwise CA IDMS/DB Reorg automatically bypasses the step.
UPDLINK (Update Set Linkage) Step--Updates the record's set linkage, using the new db-keys placed in pointer extracts by the MATCH step. Records in a copy area are then written to the DBREC file. Records that are not in a copy area, but whose pointers are being updated, are written back to the old database. If specified, an interface file for DB-EZ Reorg's inflight utility program is created.
STORE (Store) Step--Records that reside in a copy area are stored in the new database.