9.11. Geometric Functions and Operators#
The geometric typespoint
,box
,lseg
,line
,path
,polygon
, andcircle
have a large set of native support functions and operators, shown inTable 9.36,Table 9.37, andTable 9.38.
Table 9.36. Geometric Operators
Operator Description Example(s) |
---|
Adds the coordinates of the second
|
Concatenates two open paths (returns NULL if either path is closed).
|
Subtracts the coordinates of the second
|
Multiplies each point of the first argument by the second
|
Divides each point of the first argument by the second
|
Computes the total length. Available for
|
Computes the center point. Available for
|
Returns the number of points. Available for
|
Computes the point of intersection, or NULL if there is none. Available for
|
Computes the intersection of two boxes, or NULL if there is none.
|
Computes the closest point to the first object on the second object. Available for these pairs of types: (
|
Computes the distance between the objects. Available for all seven geometric types, for all combinations of
|
Does first object contain second? Available for these pairs of types: (
|
Is first object contained in or on second? Available for these pairs of types: (
|
Do these objects overlap? (One point in common makes this true.) Available for
|
Is first object strictly left of second? Available for
|
Is first object strictly right of second? Available for
|
Does first object not extend to the right of second? Available for
|
Does first object not extend to the left of second? Available for
|
Is first object strictly below second? Available for
|
Is first object strictly above second? Available for
|
Does first object not extend above second? Available for
|
Does first object not extend below second? Available for
|
Is first object below second (allows edges to touch)?
|
Is first object above second (allows edges to touch)?
|
Do these objects intersect? Available for these pairs of types: (
|
Is line horizontal?
|
Are points horizontally aligned (that is, have same y coordinate)?
|
Is line vertical?
|
Are points vertically aligned (that is, have same x coordinate)?
|
Are lines perpendicular?
|
Are lines parallel?
|
Are these objects the same? Available for
|
[a]“Rotating” a box with these operators only moves its corner points: the box is still considered to have sides parallel to the axes. Hence the box's size is not preserved, as a true rotation would do. |
Caution
Note that the“same as” operator,~=
, represents the usual notion of equality for thepoint
,box
,polygon
, andcircle
types. Some of the geometric types also have an=
operator, but=
compares for equalareas only. The other scalar comparison operators (<=
and so on), where available for these types, likewise compare areas.
Note
BeforePostgres Pro 14, the point is strictly below/above comparison operatorspoint
<<|
point
andpoint
|>>
point
were respectively called<^
and>^
. These names are still available, but are deprecated and will eventually be removed.
Table 9.37. Geometric Functions
Table 9.38. Geometric Type Conversion Functions
It is possible to access the two component numbers of apoint
as though the point were an array with indexes 0 and 1. For example, ift.p
is apoint
column thenSELECT p[0] FROM t
retrieves the X coordinate andUPDATE t SET p[1] = ...
changes the Y coordinate. In the same way, a value of typebox
orlseg
can be treated as an array of twopoint
values.