PostgreSQL/Array/Concatenate Array

array_dims(1 || ARRAY[2,3])

postgres=# SELECT array_dims(1 || ARRAY[2,3]);
 array_dims
------------
 [0:2]
(1 row)
postgres=#

array_dims(ARRAY[1,2] || 3)

postgres=# SELECT array_dims(ARRAY[1,2] || 3);
 array_dims
------------
 [1:3]
(1 row)
postgres=#

array_dims(ARRAY[[1,2],[3,4]] || ARRAY[[5,6],[7,8],[9,0]])

postgres=# SELECT array_dims(ARRAY[[1,2],[3,4]] || ARRAY[[5,6],[7,8],[9,0]]);
 array_dims
------------
 [1:5][1:2]
(1 row)
postgres=#

array_dims(ARRAY[1,2] || ARRAY[3,4,5])

postgres=# SELECT array_dims(ARRAY[1,2] || ARRAY[3,4,5]);
 array_dims
------------
 [1:5]
(1 row)
postgres=#

array_dims(ARRAY[1,2] || ARRAY[[3,4],[5,6]])

postgres=# SELECT array_dims(ARRAY[1,2] || ARRAY[[3,4],[5,6]]);
 array_dims
------------
 [0:2][1:2]
(1 row)
postgres=#

Concatenate two arrays

postgres=#
postgres=#
postgres=# SELECT ARRAY[1,2] || ARRAY[3,4];
 ?column?
-----------
 {1,2,3,4}
(1 row)
postgres=#

Concatenate two dimensional arrays

postgres=# SELECT ARRAY[5,6] || ARRAY[[1,2],[3,4]];
            ?column?
--------------------------------
 [0:2][1:2]={{5,6},{1,2},{3,4}}
(1 row)
postgres=#