A hint instructs Cirro how to execute a query.

Hints

DATACOPY

Syntax


DATACOPY /*+ … */ <source> TO <target> 

Arguments

  • FORCE_* hints are added to the SELECT for either INSERT and CTAS.

  • SOURCE_HINT text is added to INSERT, but not to CTAS (unsupported).

  • FORCE_ROWCOUNT(N) - N will be the expected source and target result.

COMPARE / SYNC

Syntax


COMPARE /*+ … */ <target> TO <source> [WITH KEY (col1,)]


SYNC /*+ … */ <target> TO <source> [WITH KEY (col1,)]

Arguments

  • COMPARE, SYNC-TO

    • FORCE_SORT({TRUE FALSE}) - Use the sorted or unsorted compare engine.
    • FORCE_TRANSFERTHREADS(N) - will cause the compare engine to use N difference loggers.
  • COMPARE without SAVE

    • FORCE_RUNMODE(system) - puts the temporary table on the given system.

Additional Information

  • For COMPARE and SYNC, the data for the two tables is expected to be substantially the same. If the FORCE_ROWCOUNT and FORCE_FETCHSIZE need to be different for the second table, re-write that table as:

SELECT /*+ hints */ * FROM table).

DUPLICATES

Syntax


DUPLICATES /*+ … */ <target> [WITH KEY (col1,)]

Additional Information

  • DUPLICATES

    • Hints are added to generated SELECT.

    • For a single table, there is no need for a data movement so many hints are irrelevant.

    • For a query, the hints can also go in the query.

DEDUP

Syntax


DEDUP /*+ … */ <target> [WITH KEY (col1,)]

Arguments

  • Since there is no data movement, most hints are irrelevant.