Re: Unexpected table size usage for small composite arrays

Erik Sjoblom <sjoblom65(at)gmail(dot)com> writes:
> I’m observing a storage behavior with arrays in a table that differs from
> my expectations, and I’d appreciate your insights. I was to store key value
> pairs in a very dense data model. I don't haver the requirement of search
> so that's why I was thinking an array of a composite type would work well.
> I can see that padding might be involved using the int4 and int8
> combination but there is more overhead. Anyone know where the following it
> coming from?

Composite values use the same 24-byte tuple headers as table rows do.
So you'd be looking at 40 bytes per array element in this example.
A large array of them would probably compress pretty well, but
it's never going to be cheap.

Can you store the int4's and int8's in two parallel arrays?

regards, tom lane