The
SQL query rewrite facility in
SPD Server examines SQL queries in order to optimize processing performance. Some SQL queries
contain SQL statements and subqueries that can be more rapidly evaluated in a separate
space, as opposed to sequentially evaluating large blocks of SQL statements. When
SPD Server detects and processes SQL statements or subqueries in a separate space,
intermediate result tables are produced. The original SQL query is dynamically rewritten,
using intermediate results tables to replace the SQL code that was evaluated separately.
The result is a dynamic process that evaluates and processes SQL queries more efficiently.
Inserting the derived intermediate data into the original SQL query does not change
the quantitative results. Rather, the processing that is required to calculate them
is expedited. The SQL query rewrite facility does not change the content of the query's
answer row set. However, the order of
the rows in the query answer set might vary if you compare the optimized query answer
set with the query answer set that SPD Server generates when the SQL query rewrite
facility is disabled.