AsterixDB Temporal Functions: Allen's Relations

Table of Contents

About Allen's Relations [Back to TOC]

AsterixDB supports Allen's relations over interval types. Allen's relations are also called Allen's interval algebra. There are totally 13 base relations described by this algebra, and all of them are supported in AsterixDB (note that interval-equals is supported by the = comparison symbol so there is no extra function for it).

A detailed description of Allen's relations can be found from its wikipedia entry.

Allen's Relations Functions [Back to TOC]

interval-before, interval-after

  • Syntax:

     interval-before(interval1, interval2)
 interval-after(interval1, interval2)

  • These two functions check whether an interval happens before/after another interval.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-before(interval1, interval2) is true if and only if interval1.end < interval2.start, and interval-after(interval1, interval2) is true if and only if interval1.start > interval2.end. If any of the two inputs is null, null is returned.

  • Examples:

     let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
 let $itv2 := interval-from-date("2005-05-01", "2012-09-09")
 return {"interval-before": interval-before($itv1, $itv2), "interval-after": interval-after($itv2, $itv1)}

  • The expected result is:

     { "interval-before": true, "interval-after": true }

interval-meets, interval-met-by

  • Syntax:

     interval-meets(interval1, interval2)
 interval-met-by(interval1, interval2)

  • These two functions check whether an interval meets with another interval.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-meets(interval1, interval2) is true if and only if interval1.end = interval2.start, and interval-met-by(interval1, interval2) is true if and only if interval1.start = interval2.end. If any of the two inputs is null, null is returned.

  • Examples:

     let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
 let $itv2 := interval-from-date("2005-01-01", "2012-09-09")
 let $itv3 := interval-from-date("2006-08-01", "2007-03-01")
 let $itv4 := interval-from-date("2004-09-10", "2006-08-01")
 return {"meets": interval-meets($itv1, $itv2), "metby": interval-met-by($itv3, $itv4)}

  • The expected result is:

     { "meets": true, "metby": true }

interval-overlaps, interval-overlapped-by, overlap

  • Syntax:

     interval-overlaps(interval1, interval2)
 interval-overlapped-by(interval1, interval2)
 overlap(interval1, interval2)

  • These functions check whether two intervals overlap with each other.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-overlaps(interval1, interval2) is true if and only if

     interval1.start < interval2.start
 AND interval2.end > interval1.end
 AND interval1.end > interval2.start

    interval-overlapped-by(interval1, interval2) is true if and only if

     interval2.start < interval1.start
 AND interval1.end > interval2.end
 AND interval2.end > interval1.start

    overlap(interval1, interval2) is true if

     (interval2.start >= interval1.start
 AND interval2.start < interval1.end)
 OR
 (interval2.end > interval1.start
 AND interval2.end <= interval.end)

    For all these functions, if any of the two inputs is null, null is returned.

    Note that interval-overlaps and interval-overlapped-by are following the Allen's relations on the definition of overlap. overlap is a syntactic sugar for the case that the intersect of two intervals is not empty.

  • Examples:

     let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
 let $itv2 := interval-from-date("2004-05-01", "2012-09-09")
 let $itv3 := interval-from-date("2006-08-01", "2007-03-01")
 let $itv4 := interval-from-date("2004-09-10", "2006-12-31")
 return {"overlaps": interval-overlaps($itv1, $itv2), 
         "overlapped-by": interval-overlapped-by($itv3, $itv4), 
         "overlapping1": overlap($itv1, $itv2), 
         "overlapping2": overlap($itv3, $itv4)}

  • The expected result is:

     { "overlaps": true, "overlapped-by": true, "overlapping1": true, "overlapping2": true }

interval-starts, interval-started-by

  • Syntax:

     interval-starts(interval1, interval2)
 interval-started-by(interval1, interval2)

  • These two functions check whether one interval starts with the other interval.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-starts(interval1, interval2) returns true if and only if

     interval1.start = interval2.start
 AND interval1.end <= interval2.end

    interval-started-by(interval1, interval2) returns true if and only if

     interval1.start = interval2.start
 AND interval2.end <= interval1.end

    For both functions, if any of the two inputs is null, null is returned.

  • Examples:

     let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
 let $itv2 := interval-from-date("2000-01-01", "2012-09-09")
 let $itv3 := interval-from-date("2006-08-01", "2007-03-01")
 let $itv4 := interval-from-date("2006-08-01", "2006-08-01")
 return {"interval-starts": interval-starts($itv1, $itv2), "interval-started-by": interval-started-by($itv3, $itv4)}

  • The expected result is:

     { "interval-starts": true, "interval-started-by": true }

interval-covers, interval-covered-by

  • Syntax:

     interval-covers(interval1, interval2)
 interval-covered-by(interval1, interval2)

  • These two functions check whether one interval covers the other interval.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-covers(interval1, interval2) is true if and only if

     interval1.start <= interval2.start
 AND interval2.end >= interval1.end

    interval-covered-by(interval1, interval2) is true if and only if

     interval2.start <= interval1.start
 AND interval1.end >= interval2.end

    For both functions, if any of the two inputs is null, null is returned.

  • Examples:

     let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
 let $itv2 := interval-from-date("2000-03-01", "2004-09-09")
 let $itv3 := interval-from-date("2006-08-01", "2007-03-01")
 let $itv4 := interval-from-date("2004-09-10", "2012-08-01")
 return {"interval-covers": interval-covers($itv1, $itv2), "interval-covered-by": interval-covered-by($itv3, $itv4)}

  • The expected result is:

     { "interval-covers": true, "interval-covered-by": true }

interval-ends, interval-ended-by

  • Syntax:

      interval-ends(interval1, interval2)
  interval-ended-by(interval1, interval2)

  • These two functions check whether one interval ends with the other interval.

  • Arguments:

    • interval1, interval2: two intervals to be compared

  • Return Value:

    A boolean value. Specifically, interval-ends(interval1, interval2) returns true if and only if

     interval1.end = interval2.end
 AND interval1.start >= interval2.start

    interval-ended-by(interval1, interval2) returns true if and only if

     interval2.end = interval1.end
 AND interval2.start >= interval1.start

    For both functions, if any of the two inputs is null, null is returned.

  • Examples:

      let $itv1 := interval-from-date("2000-01-01", "2005-01-01")
  let $itv2 := interval-from-date("1998-01-01", "2005-01-01")
  let $itv3 := interval-from-date("2006-08-01", "2007-03-01")
  let $itv4 := interval-from-date("2006-09-10", "2007-03-01")
  return {"interval-ends": interval-ends($itv1, $itv2), "interval-ended-by": interval-ended-by($itv3, $itv4) }

  • The expected result is:

      { "interval-ends": true, "interval-ended-by": true }