Written by
Brendon Pierson
on
on
TIL Selecting the last item in a postgres array
To get the last item from a postgres array
SELECT
errors[array_upper(errors, 1)]
FROM oban.oban_jobs
Oban is a great elixir job processing library. It tracks job attempts and errors with a full stack trace in a postgres errors array column. This is great to have but hard to reason about looking at the giant blob. The above snippet let’s you limit it to just the most recent error which is really all you care about.
The postgresql array_upper function “…Returns the upper bound of the requested array dimension”. The first argument is the array and the second is the dimension of the array (starting from 1).
array_upper ( anyarray, integer ) → integer
Returns the upper bound of the requested array dimension.
array_upper(ARRAY[1,8,3,7], 1) → 4'