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trim_array()
A function for removing elements from the end of an array
This entry relates to a PostgreSQL feature which is part of PostgreSQL 14, due to be released in late 2021.
trim_array() is a system function for removing elements from the end of an array.
trim_array() was added in PostgreSQL 14.
Usage
trim_array (arrayanyarray,ninteger) →anyarray
trim_array() is an SQL:2008 standard function implementing array slice functionality, specifically removing the last n elements from an array and returning the result.
If the array is multidimensional, trimming operates on dimensions rather than elements of a dimension.
Change history
- PostgreSQL 14
- added (commit 0a687c8f)
Examples
Basic usage of trim_array():
postgres=# SELECT trim_array(ARRAY['a', 'b', 'c'], 2);
trim_array
------------
{a}
(1 row)
postgres=# SELECT trim_array(ARRAY[1, 2, 3], 1);
trim_array
------------
{1,2}
(1 row)
postgres=# SELECT trim_array(ARRAY[1, 2, 3], 0);
trim_array
------------
{1,2,3}
(1 row)
Trimming multi-dimensional arrays:
postgres=# SELECT trim_array(ARRAY[ [1, 2, 3], [4, 5, 6], [7, 8, 9] ], 1);
trim_array
-------------------
{{1,2,3},{4,5,6}}
(1 row)
postgres=# SELECT trim_array(ARRAY[ [ [1, 2, 3] ], [ [4, 5, 6] ], [ [7, 8, 9] ] ], 1);
trim_array
-----------------------
{{{1,2,3}},{{4,5,6}}}
(1 row)
Specifying an invalid number of elements:
postgres=# SELECT trim_array(ARRAY['a','b','c'], -2); ERROR: number of elements to trim must be between 0 and 3
References
- PostgreSQL documentation: Array Functions