Progressive optimization for implicit cast predicates

A computer program product, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code executable by at least one processor to perform operations comprising:

• in response to receiving a query with an original predicate comparing a character value of a character data type to a literal value of a numeric data type:
• setting a number of iterations to a length of the character data type;
• for each of the number of iterations,
• generating prefix predicates based on that iteration;
• and
• processing the prefix predicates to identify a qualified index key in an index;
• normalizing the character value and the literal value;
• applying the original predicate with the normalized character value and the normalized literal value starting at the qualified index key identified in a last iteration to generate a result set for the query;
• and
• returning the result set.

A computer system, comprising:

• one or more processors, one or more computer-readable memories and one or more computer-readable, tangible storage devices;
• and
• program instructions, stored on at least one of the one or more computer-readable, tangible storage devices for execution by at least one of the one or more processors via at least one of the one or more memories, to perform operations comprising:
• in response to receiving a query with an original predicate comparing a character value of a character data type to a literal value of a numeric data type:
• setting a number of iterations to a length of the character data type;
• for each of the number of iterations,
• generating prefix predicates based on that iteration;
• and
• processing the prefix predicates to identify a qualified index key in an index;
• normalizing the character value and the literal value;
• applying the original predicate with the normalized character value and the normalized literal value starting at the qualified index key identified in a last iteration to generate a result set for the query;
• and
• returning the result set.