[OOZIE-1028] Add EL function to allow date ranges to be used for dataset ranges

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: trunk
• Fix Version/s: 3.3.2
• Component/s: coordinator
• Assignee: Robert Kanter
• Reporter: Robert Kanter
• Created: 22/Oct/12 19:29
• Updated: 20/Jul/13 00:03
• Resolved: 07/Nov/12 21:10

Description

Dataset ranges are currently specified with EL functions such as ${coord:current(int n)}, which is basically returns the nominal datetime for the nth dataset instance relative to the coordinator action creation (materialization) time (in other words, it specifies a multiple of the dataset frequency). It would be useful to have a new function that lets users specify a date range offset instead of a frequency range offset.

A new function, ${coord:offset(int n, String timeUnit)}, would be similar to the ${coord:current(int n)} function, except that the offset would be based on the TimeUnit (i.e. "MINUTE", "HOUR", "DAY", "MONTH", or "YEAR") instead of the frequency.

For example, if the frequency was 1 day, then the following would all be equivalent:
${coord:current(1)}
${coord:offset(1, "DAY")}
${coord:offset(24, "HOUR")}
${coord:offset(1440, "MINUTE")}

When specifying dataset instances, the resolved value of ${coord:offset(int n, String timeUnit)} would have to line up with an offset of a multiple of the frequency when used in an <instance> element.
However, when used in <start-instance> and <end-instance>, the function would automatically resolve the range of instances to match the offset of a multiple of the frequency
that would fall between the <start-instance> and <end-instance>. For example, if the frequency is 1 hour and the <start-instance> is ${coord:offset(-90, "MINUTE")} (-1.5 hours).
then the <start-instance> would be effectively equivalent to ${coord:offset(-60, "MINUTE")} as we are dealing with a range.