does postgresql array type preserve order of array?

Question

I read over the docs for PostgreSQL v 9.3 arrays (http://www.postgresql.org/docs/9.3/static/arrays.html), but I don't see the question of ordering covered. Can someone confirm that Postgres preserves the insertion order/original order of an array when it's inserted into an array column? This seems to be the case but I would like absolute confirmation.

Thank you.

Answer 1

The documentation is entirely clear that arrays are useful in scenarios where order is important, inasmuch as it explicitly documents querying against specific positions within an array. If those positions were not reliable, these queries would have no meaning. (Using the word "array" is also clear on this point, being as it is a term of the art: An array is an ordered datatype by its nature; an unordered collection allowed to contain duplicates would be a bag, not an array, just as an unordered collection in which duplicates were not allowed would be a set).

See the examples given in section 8.1.4.3, of "pay by quarter", with index position within the array indicating which quarter is being queried against.