9.20. 範圍函式及運算子

See Section 8.17 for an overview of range types.

Table 9.55 shows the specialized operators available for range types. Table 9.56 shows the specialized operators available for multirange types. In addition to those, the usual comparison operators shown in Table 9.1 are available for range and multirange types. The comparison operators order first by the range lower bounds, and only if those are equal do they compare the upper bounds. The multirange operators compare each range until one is unequal. This does not usually result in a useful overall ordering, but the operators are provided to allow unique indexes to be constructed on ranges.

Table 9.55. Range Operators

Operator Description Example(s)
anyrange @> anyrange → boolean Does the first range contain the second? int4range(2,4) @> int4range(2,3) → t
anyrange @> anyelement → boolean Does the range contain the element? '[2011-01-01,2011-03-01)'::tsrange @> '2011-01-10'::timestamp → t
anyrange <@ anyrange → boolean Is the first range contained by the second? int4range(2,4) <@ int4range(1,7) → t
anyelement <@ anyrange → boolean Is the element contained in the range? 42 <@ int4range(1,7) → f
anyrange && anyrange → boolean Do the ranges overlap, that is, have any elements in common? int8range(3,7) && int8range(4,12) → t
anyrange << anyrange → boolean Is the first range strictly left of the second? int8range(1,10) << int8range(100,110) → t
anyrange >> anyrange → boolean Is the first range strictly right of the second? int8range(50,60) >> int8range(20,30) → t
anyrange &< anyrange → boolean Does the first range not extend to the right of the second? int8range(1,20) &< int8range(18,20) → t
anyrange &> anyrange → boolean Does the first range not extend to the left of the second? int8range(7,20) &> int8range(5,10) → t
anyrange -|- anyrange → boolean Are the ranges adjacent? numrange(1.1,2.2) -|- numrange(2.2,3.3) → t
anyrange + anyrange → anyrange Computes the union of the ranges. The ranges must overlap or be adjacent, so that the union is a single range (but see range_merge()). numrange(5,15) + numrange(10,20) → [5,20)
anyrange * anyrange → anyrange Computes the intersection of the ranges. int8range(5,15) * int8range(10,20) → [10,15)
anyrange - anyrange → anyrange Computes the difference of the ranges. The second range must not be contained in the first in such a way that the difference would not be a single range. int8range(5,15) - int8range(10,20) → [5,10)

Table 9.56. Multirange Operators

Operator Description Example(s)
anymultirange @> anymultirange → boolean Does the first multirange contain the second? '{[2,4)}'::int4multirange @> '{[2,3)}'::int4multirange → t
anymultirange @> anyrange → boolean Does the multirange contain the range? '{[2,4)}'::int4multirange @> int4range(2,3) → t
anymultirange @> anyelement → boolean Does the multirange contain the element? '{[2011-01-01,2011-03-01)}'::tsmultirange @> '2011-01-10'::timestamp → t
anyrange @> anymultirange → boolean Does the range contain the multirange? '[2,4)'::int4range @> '{[2,3)}'::int4multirange → t
anymultirange <@ anymultirange → boolean Is the first multirange contained by the second? '{[2,4)}'::int4multirange <@ '{[1,7)}'::int4multirange → t
anymultirange <@ anyrange → boolean Is the multirange contained by the range? '{[2,4)}'::int4multirange <@ int4range(1,7) → t
anyrange <@ anymultirange → boolean Is the range contained by the multirange? int4range(2,4) <@ '{[1,7)}'::int4multirange → t
anyelement <@ anymultirange → boolean Is the element contained by the multirange? 4 <@ '{[1,7)}'::int4multirange → t
anymultirange && anymultirange → boolean Do the multiranges overlap, that is, have any elements in common? '{[3,7)}'::int8multirange && '{[4,12)}'::int8multirange → t
anymultirange && anyrange → boolean Does the multirange overlap the range? '{[3,7)}'::int8multirange && int8range(4,12) → t
anyrange && anymultirange → boolean Does the range overlap the multirange? int8range(3,7) && '{[4,12)}'::int8multirange → t
anymultirange << anymultirange → boolean Is the first multirange strictly left of the second? '{[1,10)}'::int8multirange << '{[100,110)}'::int8multirange → t
anymultirange << anyrange → boolean Is the multirange strictly left of the range? '{[1,10)}'::int8multirange << int8range(100,110) → t
anyrange << anymultirange → boolean Is the range strictly left of the multirange? int8range(1,10) << '{[100,110)}'::int8multirange → t
anymultirange >> anymultirange → boolean Is the first multirange strictly right of the second? '{[50,60)}'::int8multirange >> '{[20,30)}'::int8multirange → t
anymultirange >> anyrange → boolean Is the multirange strictly right of the range? '{[50,60)}'::int8multirange >> int8range(20,30) → t
anyrange >> anymultirange → boolean Is the range strictly right of the multirange? int8range(50,60) >> '{[20,30)}'::int8multirange → t
anymultirange &< anymultirange → boolean Does the first multirange not extend to the right of the second? '{[1,20)}'::int8multirange &< '{[18,20)}'::int8multirange → t
anymultirange &< anyrange → boolean Does the multirange not extend to the right of the range? '{[1,20)}'::int8multirange &< int8range(18,20) → t
anyrange &< anymultirange → boolean Does the range not extend to the right of the multirange? int8range(1,20) &< '{[18,20)}'::int8multirange → t
anymultirange &> anymultirange → boolean Does the first multirange not extend to the left of the second? '{[7,20)}'::int8multirange &> '{[5,10)}'::int8multirange → t
anymultirange &> anyrange → boolean Does the multirange not extend to the left of the range? '{[7,20)}'::int8multirange &> int8range(5,10) → t
anyrange &> anymultirange → boolean Does the range not extend to the left of the multirange? int8range(7,20) &> '{[5,10)}'::int8multirange → t
anymultirange -|- anymultirange → boolean Are the multiranges adjacent? '{[1.1,2.2)}'::nummultirange -|- '{[2.2,3.3)}'::nummultirange → t
anymultirange -|- anyrange → boolean Is the multirange adjacent to the range? '{[1.1,2.2)}'::nummultirange -|- numrange(2.2,3.3) → t
anyrange -|- anymultirange → boolean Is the range adjacent to the multirange? numrange(1.1,2.2) -|- '{[2.2,3.3)}'::nummultirange → t
anymultirange + anymultirange → anymultirange Computes the union of the multiranges. The multiranges need not overlap or be adjacent. '{[5,10)}'::nummultirange + '{[15,20)}'::nummultirange → {[5,10), [15,20)}
anymultirange * anymultirange → anymultirange Computes the intersection of the multiranges. '{[5,15)}'::int8multirange * '{[10,20)}'::int8multirange → {[10,15)}
anymultirange - anymultirange → anymultirange Computes the difference of the multiranges. '{[5,20)}'::int8multirange - '{[10,15)}'::int8multirange → {[5,10), [15,20)}

The left-of/right-of/adjacent operators always return false when an empty range or multirange is involved; that is, an empty range is not considered to be either before or after any other range.

Elsewhere empty ranges and multiranges are treated as the additive identity: anything unioned with an empty value is itself. Anything minus an empty value is itself. An empty multirange has exactly the same points as an empty range. Every range contains the empty range. Every multirange contains as many empty ranges as you like.

The range union and difference operators will fail if the resulting range would need to contain two disjoint sub-ranges, as such a range cannot be represented. There are separate operators for union and difference that take multirange parameters and return a multirange, and they do not fail even if their arguments are disjoint. So if you need a union or difference operation for ranges that may be disjoint, you can avoid errors by first casting your ranges to multiranges.

Table 9.57 shows the functions available for use with range types. Table 9.58 shows the functions available for use with multirange types.

Table 9.57. Range Functions

Function Description Example(s)
lower ( anyrange ) → anyelement Extracts the lower bound of the range (NULL if the range is empty or the lower bound is infinite). lower(numrange(1.1,2.2)) → 1.1
upper ( anyrange ) → anyelement Extracts the upper bound of the range (NULL if the range is empty or the upper bound is infinite). upper(numrange(1.1,2.2)) → 2.2
isempty ( anyrange ) → boolean Is the range empty? isempty(numrange(1.1,2.2)) → f
lower_inc ( anyrange ) → boolean Is the range's lower bound inclusive? lower_inc(numrange(1.1,2.2)) → t
upper_inc ( anyrange ) → boolean Is the range's upper bound inclusive? upper_inc(numrange(1.1,2.2)) → f
lower_inf ( anyrange ) → boolean Is the range's lower bound infinite? lower_inf('(,)'::daterange) → t
upper_inf ( anyrange ) → boolean Is the range's upper bound infinite? upper_inf('(,)'::daterange) → t
range_merge ( anyrange, anyrange ) → anyrange Computes the smallest range that includes both of the given ranges. range_merge('[1,2)'::int4range, '[3,4)'::int4range) → [1,4)

Table 9.58. Multirange Functions

Function Description Example(s)
lower ( anymultirange ) → anyelement Extracts the lower bound of the multirange (NULL if the multirange is empty or the lower bound is infinite). lower('{[1.1,2.2)}'::nummultirange) → 1.1
upper ( anymultirange ) → anyelement Extracts the upper bound of the multirange (NULL if the multirange is empty or the upper bound is infinite). upper('{[1.1,2.2)}'::nummultirange) → 2.2
isempty ( anymultirange ) → boolean Is the multirange empty? isempty('{[1.1,2.2)}'::nummultirange) → f
lower_inc ( anymultirange ) → boolean Is the multirange's lower bound inclusive? lower_inc('{[1.1,2.2)}'::nummultirange) → t
upper_inc ( anymultirange ) → boolean Is the multirange's upper bound inclusive? upper_inc('{[1.1,2.2)}'::nummultirange) → f
lower_inf ( anymultirange ) → boolean Is the multirange's lower bound infinite? lower_inf('{(,)}'::datemultirange) → t
upper_inf ( anymultirange ) → boolean Is the multirange's upper bound infinite? upper_inf('{(,)}'::datemultirange) → t
range_merge ( anymultirange ) → anyrange Computes the smallest range that includes the entire multirange. range_merge('{[1,2), [3,4)}'::int4multirange) → [1,4)
multirange ( anyrange ) → anymultirange Returns a multirange containing just the given range. multirange('[1,2)'::int4range) → {[1,2)}
unnest ( anymultirange ) → setof anyrange Expands a multirange into a set of ranges. The ranges are read out in storage order (ascending). unnest('{[1,2), [3,4)}'::int4multirange) → [1,2) [3,4)

The lower_inc, upper_inc, lower_inf, and upper_inf functions all return false for an empty range or multirange.