Selecting the scan method
IMS™ Index Builder provides a sequential scan technology for building primary, secondary, and ILDS indexes, and this sequential scan technology is used as the default scan method. However, you can change the scan method to apply the scan method that was used in IMS Index Builder Version 2.3.
About this task
When you build a primary index and secondary indexes together in IMS Index Builder Version 2.3, the primary database was scanned twice, once by using the sequential scan method and once by using the hierarchical HPU scan method. However, in this version of IMS Index Builder, the primary database is scanned only once by using the sequential scan method, which reduces the elapsed time.
When the sequential scan method is used to build one or more secondary indexes, several sort tasks are started depending on the segment level of the index sources. The segment occurrences of the primary database are read in physical order, then the index pointers and the index keys are collected and sorted in hierarchical order. For example, when segment level of an index source is the second level of dependent segments, two sort tasks (IIUSRTV1 and IIUSRTV2) are started, and when the index target or the index source is a variable-length segment, an additional sort task (IIUSRTD0) is started.
IIUSRTV1 PPP9PPP1 SEQSCAN SORT MESSAGES: DURATION
----------------------------------------------------------84--
ICE200I 0 IDENTIFIER FROM CALLING PROGRAM IS CA12
ICE201I A RECORD TYPE IS F - DATA STARTS IN POSITION 1
ICE751I 0 C5-I40658 C6-I35397 C7-I35397 C8-I40658 E4-I40658 C9-I35397 E5-I38877 E6-I31999 C4-I31999 E7-I40658
ICE143I 0 BLOCKSET SORT TECHNIQUE SELECTED
ICE250I 0 VISIT http://www.ibm.com/storage/dfsort FOR DFSORT PAPERS, EXAMPLES AND MORE
ICE000I 0 - CONTROL STATEMENTS FOR 5650-ZOS, Z/OS DFSORT V2R2 - 08:03 ON TUE MAY 29, 2018 -
SORT FIELDS=(001,010,CH,A),DYNALLOC,FILSZ=E000001000000
RECORD TYPE=F,LENGTH=00195
OPTION MSGDDN=IIUSRTV1,SORTDD=T009
DEBUG ABEND
ICE193I 0 ICEAM2 INVOCATION ENVIRONMENT IN EFFECT - ICEAM2 ENVIRONMENT SELECTED
:
These sort tasks require additional sort workspace. The sort file size of IIUSRTVx is estimated based on the sum of index records, and the estimated value is given to the SORT FILSZ option. When the VSAM data set for the index is not reused, the number of index records is estimated based on the allocation characteristics of the VSAM data set. You can override the estimated value by using the SORTFSZ control statement.
When additional sort workspace is not available, you can use the scan method that was used in IMS Index Builder Version 2.3.
Procedure
IIUE096M A0000777 008C0BF8 IB CONTROL FLOW EVENT 603 AT IIUSCA01 12.00.00.00
SEQUENTIAL SERIAL SCANNER ACTIVATED
IIUE096M A0000777 006D5D08 IB CONTROL FLOW EVENT 609 AT IIUSCA12 12.00.00.00
SEQUENTIAL SAS SCANNER ACTIVATED
IIUE096M A0000777 007A1088 IB CONTROL FLOW EVENT 623 AT IIUSCA55 12.00.00.00
HIERARCHICAL HPU SCANNER ACTIVATED