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 @> anyrangeboolean

Does the first range contain the second?

int4range(2,4) @> int4range(2,3)t

anyrange @> anyelementboolean

Does the range contain the element?

'[2011-01-01,2011-03-01)'::tsrange @> '2011-01-10'::timestampt

anyrange <@ anyrangeboolean

Is the first range contained by the second?

int4range(2,4) <@ int4range(1,7)t

anyelement <@ anyrangeboolean

Is the element contained in the range?

42 <@ int4range(1,7)f

anyrange && anyrangeboolean

Do the ranges overlap, that is, have any elements in common?

int8range(3,7) && int8range(4,12)t

anyrange << anyrangeboolean

Is the first range strictly left of the second?

int8range(1,10) << int8range(100,110)t

anyrange >> anyrangeboolean

Is the first range strictly right of the second?

int8range(50,60) >> int8range(20,30)t

anyrange &< anyrangeboolean

Does the first range not extend to the right of the second?

int8range(1,20) &< int8range(18,20)t

anyrange &> anyrangeboolean

Does the first range not extend to the left of the second?

int8range(7,20) &> int8range(5,10)t

anyrange -|- anyrangeboolean

Are the ranges adjacent?

numrange(1.1,2.2) -|- numrange(2.2,3.3)t

anyrange + anyrangeanyrange

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 * anyrangeanyrange

Computes the intersection of the ranges.

int8range(5,15) * int8range(10,20)[10,15)

anyrange - anyrangeanyrange

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 @> anymultirangeboolean

Does the first multirange contain the second?

'{[2,4)}'::int4multirange @> '{[2,3)}'::int4multiranget

anymultirange @> anyrangeboolean

Does the multirange contain the range?

'{[2,4)}'::int4multirange @> int4range(2,3)t

anymultirange @> anyelementboolean

Does the multirange contain the element?

'{[2011-01-01,2011-03-01)}'::tsmultirange @> '2011-01-10'::timestampt

anyrange @> anymultirangeboolean

Does the range contain the multirange?

'[2,4)'::int4range @> '{[2,3)}'::int4multiranget

anymultirange <@ anymultirangeboolean

Is the first multirange contained by the second?

'{[2,4)}'::int4multirange <@ '{[1,7)}'::int4multiranget

anymultirange <@ anyrangeboolean

Is the multirange contained by the range?

'{[2,4)}'::int4multirange <@ int4range(1,7)t

anyrange <@ anymultirangeboolean

Is the range contained by the multirange?

int4range(2,4) <@ '{[1,7)}'::int4multiranget

anyelement <@ anymultirangeboolean

Is the element contained by the multirange?

4 <@ '{[1,7)}'::int4multiranget

anymultirange && anymultirangeboolean

Do the multiranges overlap, that is, have any elements in common?

'{[3,7)}'::int8multirange && '{[4,12)}'::int8multiranget

anymultirange && anyrangeboolean

Does the multirange overlap the range?

'{[3,7)}'::int8multirange && int8range(4,12)t

anyrange && anymultirangeboolean

Does the range overlap the multirange?

int8range(3,7) && '{[4,12)}'::int8multiranget

anymultirange << anymultirangeboolean

Is the first multirange strictly left of the second?

'{[1,10)}'::int8multirange << '{[100,110)}'::int8multiranget

anymultirange << anyrangeboolean

Is the multirange strictly left of the range?

'{[1,10)}'::int8multirange << int8range(100,110)t

anyrange << anymultirangeboolean

Is the range strictly left of the multirange?

int8range(1,10) << '{[100,110)}'::int8multiranget

anymultirange >> anymultirangeboolean

Is the first multirange strictly right of the second?

'{[50,60)}'::int8multirange >> '{[20,30)}'::int8multiranget

anymultirange >> anyrangeboolean

Is the multirange strictly right of the range?

'{[50,60)}'::int8multirange >> int8range(20,30)t

anyrange >> anymultirangeboolean

Is the range strictly right of the multirange?

int8range(50,60) >> '{[20,30)}'::int8multiranget

anymultirange &< anymultirangeboolean

Does the first multirange not extend to the right of the second?

'{[1,20)}'::int8multirange &< '{[18,20)}'::int8multiranget

anymultirange &< anyrangeboolean

Does the multirange not extend to the right of the range?

'{[1,20)}'::int8multirange &< int8range(18,20)t

anyrange &< anymultirangeboolean

Does the range not extend to the right of the multirange?

int8range(1,20) &< '{[18,20)}'::int8multiranget

anymultirange &> anymultirangeboolean

Does the first multirange not extend to the left of the second?

'{[7,20)}'::int8multirange &> '{[5,10)}'::int8multiranget

anymultirange &> anyrangeboolean

Does the multirange not extend to the left of the range?

'{[7,20)}'::int8multirange &> int8range(5,10)t

anyrange &> anymultirangeboolean

Does the range not extend to the left of the multirange?

int8range(7,20) &> '{[5,10)}'::int8multiranget

anymultirange -|- anymultirangeboolean

Are the multiranges adjacent?

'{[1.1,2.2)}'::nummultirange -|- '{[2.2,3.3)}'::nummultiranget

anymultirange -|- anyrangeboolean

Is the multirange adjacent to the range?

'{[1.1,2.2)}'::nummultirange -|- numrange(2.2,3.3)t

anyrange -|- anymultirangeboolean

Is the range adjacent to the multirange?

numrange(1.1,2.2) -|- '{[2.2,3.3)}'::nummultiranget

anymultirange + anymultirangeanymultirange

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 * anymultirangeanymultirange

Computes the intersection of the multiranges.

'{[5,15)}'::int8multirange * '{[10,20)}'::int8multirange{[10,15)}

anymultirange - anymultirangeanymultirange

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.