Re: Array access performance

Andreas Brandl <ml@3.141592654.de> writes:
> I'm looking for a hint how array access performs in PostgreSQL in respect to performance. Normally I would expect
accessof a 1-dimensional Array at slot i (array[i]) to perform in constant time (random access). 

> Is this also true for postgres' arrays?

Only if the element type is fixed-length (no strings for instance) and
the array does not contain, and never has contained, any nulls.
Otherwise a scan through all the previous elements is required to find
a particular element.

By and large, if you're thinking of using arrays large enough to make
this an interesting question, I would say stop right there and redesign
your database schema.  You're not thinking relationally, and it's gonna
cost ya.

            regards, tom lane