9.14. Array Functions and Operators

Table 9-35 shows the operators available for array types.

Table 9-35. array Operators

= equalARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3]t
<> not equalARRAY[1,2,3] <> ARRAY[1,2,4]t
< less thanARRAY[1,2,3] < ARRAY[1,2,4]t
> greater thanARRAY[1,4,3] > ARRAY[1,2,4]t
<= less than or equalARRAY[1,2,3] <= ARRAY[1,2,3]t
>= greater than or equalARRAY[1,4,3] >= ARRAY[1,4,3]t
@> containsARRAY[1,4,3] @> ARRAY[3,1]t
<@ is contained byARRAY[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 concatenationARRAY[1,2,3] || ARRAY[4,5,6]{1,2,3,4,5,6}
|| array-to-array concatenationARRAY[1,2,3] || ARRAY[[4,5,6],[7,8,9]]{{1,2,3},{4,5,6},{7,8,9}}
|| element-to-array concatenation3 || ARRAY[4,5,6]{3,4,5,6}
|| array-to-element concatenationARRAY[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

FunctionReturn TypeDescriptionExampleResult
array_append(anyarray, anyelement) anyarrayappend an element to the end of an arrayarray_append(ARRAY[1,2], 3){1,2,3}
array_cat(anyarray, anyarray) anyarrayconcatenate two arraysarray_cat(ARRAY[1,2,3], ARRAY[4,5]){1,2,3,4,5}
array_dims(anyarray) textreturns a text representation of array's dimensionsarray_dims(ARRAY[[1,2,3], [4,5,6]])[1:2][1:3]
array_lower(anyarray, int) intreturns lower bound of the requested array dimensionarray_lower('[0:2]={1,2,3}'::int[], 1)0
array_prepend(anyelement, anyarray) anyarrayappend an element to the beginning of an arrayarray_prepend(1, ARRAY[2,3]){1,2,3}
array_to_string(anyarray, text) textconcatenates array elements using provided delimiterarray_to_string(ARRAY[1, 2, 3], '~^~')1~^~2~^~3
array_upper(anyarray, int) intreturns upper bound of the requested array dimensionarray_upper(ARRAY[1,2,3,4], 1)4
string_to_array(text, text) text[]splits string into array elements using provided delimiterstring_to_array('xx~^~yy~^~zz', '~^~'){xx,yy,zz}