Re: Is array_append O(n)?

[Rob Nikander]

> On Jun 18, 2019, at 7:37 PM, Alvaro Herrera <alvhe...@2ndquadrant.com> wrote:
> 
> On 2019-Jun-18, Rob Nikander wrote:
> 
>> Does `array_append(arr, elt)` create a new array and copy everything?
>> In other words, is it O(n) or O(1)? […]
> 
> Starting with 9.5, there's an optimization that I think is supposed to
> make it O(1):

Sweet! Thanks. Now I’d like to know how to tell if that optimization is being 
used, or not. 

Same question for the a way to pop an element off the end in O(1) time.