Add a system function mechanism and table of functions, including a set of initial functions.

• Key: DERBY-475
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Daniel John Debrunner
• Reporter: Daniel John Debrunner
• Component/s: SQL
• Fix Version/s: 10.2.1.6

Description

Add a mechanism for system functions to be easily added. Resolution of functions will check SYSFUN.<name> for a function call in SQL when the function is not qualified by a schema. If the current schema does not have a function matching the name, then an additional resolution is made using SYSFUN.<name>.

Add a table driven mechanism for simple single argument functions (could be expanded in the future).

Add these functions

/*
** SYSFUN functions
*[0] = FUNCTION name
*[1] = RETURNS type
*[2] = Java class
*[3] = method name
*[4] = parameter type (single parameter)
*
*/
private static final String[][] SYSFUN_FUNCTIONS = {
{"ACOS", "DOUBLE", "java.lang.Math", "acos", "DOUBLE"},
{"ASIN", "DOUBLE", "java.lang.Math", "asin", "DOUBLE"},
{"ATAN", "DOUBLE", "java.lang.Math", "atan", "DOUBLE"},
{"COS", "DOUBLE", "java.lang.Math", "cos", "DOUBLE"},
{"SIN", "DOUBLE", "java.lang.Math", "sin", "DOUBLE"},
{"TAN", "DOUBLE", "java.lang.Math", "tan", "DOUBLE"},
{"DEGREES", "DOUBLE", "java.lang.Math", "toDegrees", "DOUBLE"},
{"RADIANS", "DOUBLE", "java.lang.Math", "toRadians", "DOUBLE"},
{"LN", "DOUBLE", "java.lang.Math", "log", "DOUBLE"},
{"EXP", "DOUBLE", "java.lang.Math", "exp", "DOUBLE"},
{"CEIL", "DOUBLE", "java.lang.Math", "ceil", "DOUBLE"},
{"CEILING", "DOUBLE", "java.lang.Math", "ceil", "DOUBLE"},
{"FLOOR", "DOUBLE", "java.lang.Math", "floor", "DOUBLE"},

};

Comments

[Daniel John Debrunner]

Committed revision 226528.
Table added to DataDictionaryImpl with the set of functions above and tests in functions.sql.
Other single argument functions can be easily added through this mechanism.

[Daniel John Debrunner]

These new match functions should use the methods in the class java.lang.StrictMath instead of java.lang.Math. Provides consistent/portable behaviour across different JVMs.

[Daniel John Debrunner]

Complete set of functions added is:

ACOS, ASIN, ATAN, COS, SIN, TAN, PI
DEGREES, RADIANS, EXP, LN, LOG, LOG10, CEIL, CEILING, FLOOR