Index example: Ordering and grouping on the same columns with ALWCPYDTA(*OPTIMIZE) and a unique-weight sort sequence table

 

Ordering and grouping on the same columns with ALWCPYDTA(*OPTIMIZE) and a unique-weight sort sequence table (SRTSEQ(*LANGIDUNQ) LANGID(ENU)).

  SELECT JOB, SALARY FROM STAFF    GROUP BY JOB, SALARY    ORDER BY JOB, SALARY

When using the OPNQRYF command, specify:

OPNQRYF FILE((STAFF)) FORMAT(FORMAT3)
   GRPFLD(JOB SALARY)
   KEYFLD(JOB SALARY)
   SRTSEQ(*LANGIDUNQ) LANGID(ENU)
   ALWCPYDTA(*OPTIMIZE)

The system can use UNQIX2 to satisfy both the grouping and ordering requirements. If index UNQIX2 did not exist, the system does one of the following actions:

• Create an index using a sort sequence table of *LANGIDUNQ or

• Use index HEXIX2 to satisfy the grouping and to perform a sort to satisfy the ordering

 

Parent topic:

Examples of indexes