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SQL Anywhere 12.0.0 (Français) » SQL Anywhere Server - SQL Usage » Query optimization and execution » Query execution algorithms » Types of 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.

With 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