Table 9-35 shows the operators
available for array types.
Table 9-35. array Operators
Operator
Description
Example
Result
=
equal
ARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3]
t
<>
not equal
ARRAY[1,2,3] <> ARRAY[1,2,4]
t
<
less than
ARRAY[1,2,3] < ARRAY[1,2,4]
t
>
greater than
ARRAY[1,4,3] > ARRAY[1,2,4]
t
<=
less than or equal
ARRAY[1,2,3] <= ARRAY[1,2,3]
t
>=
greater than or equal
ARRAY[1,4,3] >= ARRAY[1,4,3]
t
@>
contains
ARRAY[1,4,3] @> ARRAY[3,1]
t
<@
is contained by
ARRAY[2,7] <@ ARRAY[1,7,4,2,6]
t
&&
overlap (have elements in common)
ARRAY[1,4,3] && ARRAY[2,1]
t
||
array-to-array concatenation
ARRAY[1,2,3] || ARRAY[4,5,6]
{1,2,3,4,5,6}
||
array-to-array concatenation
ARRAY[1,2,3] || ARRAY[[4,5,6],[7,8,9]]
{{1,2,3},{4,5,6},{7,8,9}}
||
element-to-array concatenation
3 || ARRAY[4,5,6]
{3,4,5,6}
||
array-to-element concatenation
ARRAY[4,5,6] || 7
{4,5,6,7}
Array comparisons compare the array contents element-by-element,
using the default B-Tree comparison function for the element data type.
In multidimensional arrays the elements are visited in row-major order
(last subscript varies most rapidly).
If the contents of two arrays are equal but the dimensionality is
different, the first difference in the dimensionality information
determines the sort order. (This is a change from versions of
PostgreSQL prior to 8.2: older versions would claim
that two arrays with the same contents were equal, even if the
number of dimensions or subscript ranges were different.)
See Section 8.10 for more details about array operator
behavior.
Table 9-36 shows the functions
available for use with array types. See Section 8.10
for more discussion and examples of the use of these functions.
Table 9-36. array Functions
Function
Return Type
Description
Example
Result
array_append(anyarray, anyelement)
anyarray
append an element to the end of an array
array_append(ARRAY[1,2], 3)
{1,2,3}
array_cat(anyarray, anyarray)
anyarray
concatenate two arrays
array_cat(ARRAY[1,2,3], ARRAY[4,5])
{1,2,3,4,5}
array_dims(anyarray)
text
returns a text representation of array's dimensions
array_dims(ARRAY[[1,2,3], [4,5,6]])
[1:2][1:3]
array_lower(anyarray, int)
int
returns lower bound of the requested array dimension
array_lower('[0:2]={1,2,3}'::int[], 1)
0
array_prepend(anyelement, anyarray)
anyarray
append an element to the beginning of an array
array_prepend(1, ARRAY[2,3])
{1,2,3}
array_to_string(anyarray, text)
text
concatenates array elements using provided delimiter
array_to_string(ARRAY[1, 2, 3], '~^~')
1~^~2~^~3
array_upper(anyarray, int)
int
returns upper bound of the requested array dimension
array_upper(ARRAY[1,2,3,4], 1)
4
string_to_array(text, text)
text[]
splits string into array elements using provided delimiter
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