Return the first, the last, or the nth distinct cell identifier of a temporal value

startValue(tcell) → cell
endValue(tcell) → cell
valueN(tcell,integer) → cell

valueN counts from one and returns NULL when n is out of range.

SELECT startValue(th3index '831c02fffffffff@2001-01-01');
-- 831c02fffffffff
SELECT endValue(th3index '{831c02fffffffff@2001-01-01, 831c00fffffffff@2001-01-02}');
-- 831c00fffffffff
SELECT valueN(th3index '{831c02fffffffff@2001-01-01, 831c00fffffffff@2001-01-02}', 1);
-- 831c02fffffffff
SELECT startValue(tquadbin '48a6227affffffff@2001-01-01');
-- 48a6227affffffff
SELECT endValue(tquadbin '{48a6227affffffff@2001-01-01, 485623ffffffffff@2001-01-02}');
-- 485623ffffffffff
SELECT valueN(tquadbin '{48a6227affffffff@2001-01-01, 485623ffffffffff@2001-01-02}', 1);
-- 48a6227affffffff
SELECT startValue(ts2cell '47c3c@2001-01-01');
-- 47c3c
SELECT endValue(ts2cell '{47c3c@2001-01-01, 47c4@2001-01-02}');
-- 47c4
SELECT valueN(ts2cell '{47c3c@2001-01-01, 47c4@2001-01-02}', 1);
-- 47c3c

Return the set of distinct cell identifiers the trajectory takes

getValues(tcell) → cellset

SELECT getValues(th3index '831c02fffffffff@2001-01-01');
-- {"831c02fffffffff"}
SELECT getValues(th3index '[831c02fffffffff@2001-01-01, 831c00fffffffff@2001-01-02,
    880326b885fffff@2001-01-03]');
-- {"831c00fffffffff", "831c02fffffffff", "880326b885fffff"}
SELECT getValues(tquadbin '48a6227affffffff@2001-01-01');
-- {"48a6227affffffff"}
SELECT getValues(tquadbin '{48a6227affffffff@2001-01-01, 485623ffffffffff@2001-01-02}');
-- {"485623ffffffffff", "48a6227affffffff"}
SELECT getValues(ts2cell '47c3c@2001-01-01');
-- {"47c3c"}
SELECT getValues(ts2cell '{47c3c@2001-01-01, 47c4@2001-01-02}');
-- {"47c3c", "47c4"}

Return the cell identifier at a given timestamp, using step interpolation

valueAtTimestamp(tcell,timestamptz) → cell

SELECT valueAtTimestamp(th3index
  '[831c02fffffffff@2001-01-01, 831c00fffffffff@2001-01-05]', '2001-01-03');
-- 831c02fffffffff
SELECT valueAtTimestamp(tquadbin
  '[48a6227affffffff@2001-01-01, 485623ffffffffff@2001-01-05]', '2001-01-03');
-- 48a6227affffffff
SELECT valueAtTimestamp(ts2cell '47c3c@2001-01-01', timestamptz '2001-01-01');
-- 47c3c