SET Options

REQUIRED_OPTIMIZATION

SET REQUIRED_OPTIMIZATION options

The Required Optimization option enforces specified optimization rules on an SQL select statement. In the event that a select cannot be optimized according to those rules, the select will stop processing and return an error. Subsequent operations against that select, such as fetches and exports, will be disallowed.

The required optimization feature is triggered using the REQUIRED_OPTIMIZATION options of oaselect or oaexecsql.

The REQUIRED_OPTIMIZATION option is also supported on oaopencursor, indicating that the required optimization should apply to all selects performed on this cursor.

If a REQUIRED_OPTIMIZATION option is specified on both the oaopencursor and the oaselect or oaexecsql, the required optimization settings on oaselect and oaexecsql take precedence.

REQUIRED_OPTIMIZATION Settings

NO_XREF_FILES -- Do not allow cross-reference files

NO_UNOPTIMIZED_CRITERIA -- Do not allow unoptimized criteria

NO_CARTESIAN_PRODUCTS -- Do not allow Cartesian products between tables

NO_UNOPTIMIZED_AGGREGATIONS -- Do not allow unoptimized aggregations

NO_UNOPTIMIZED_SORTS -- Do not allow unoptimized ORDER BY clauses

NO_SEQUENTIAL_SCANS -- Do not allow sequential table scans

NO_SEQUENTIAL_TABLE_JOINS -- Do not allow joins requiring sequential table scans

Example

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