Improved DDL Performance

CA IDMS now considers statistics when processing SQL DDL statements. Considering statistics may result in fewer I/Os and faster execution when executing the following DDL statements that access all rows of a table:

CREATE INDEX, ALTER INDEX
CREATE TABLE, ALTER TABLE
ALTER CONSTRAINT, DROP CONSTRAINT

When CA IDMS must access all table rows during DDL statement execution, it uses either a DBKEY or clustering index if one is available. However, if no such index exists, CA IDMS must decide whether to access rows through some other index or through an area sweep. CA IDMS now chooses between these alternatives based on table statistics. If there are fewer rows than half the number of pages in the area, the table is accessed through the index; otherwise, it is accessed through an area sweep.