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SQL Anywhere 11.0.0 » SQL Anywhere Server - SQL Usage » Query Optimizer » Query optimization and execution » Query execution algorithms » Miscellaneous algorithms


RowConstructor algorithm (ROWS)

RowConstructor is a specialized operator that creates a virtual row for use as the input to other algorithms. RowConstructor is used in the following two ways:

  • With an INSERT ... VALUES statement, the expressions referenced in the VALUES clause (typically literal constants and/or host variables) form a virtual row to be inserted. In this case, a row constructor appears in the graphical plan underneath an INSERT.
  • Direct or indirect references to the system table SYS.DUMMY are transformed automatically to use RowConstructor, replacing the need for a table scan of SYS.DUMMY, and eliminating the need to latch the (single) page of the DUMMY table.

In the case of short or long text plans, the plan string continues to contain a reference to the table SYS.DUMMY, even though RowConstructor was used instead of performing a table scan of SYS.DUMMY.

See also