Thanks Tom for your response! Yes, I did expect that the first element should take 24+12 bytes and let's round that to 50 bytes. If I store another element, I would expect another 12. (or 16 depending on padding) and take say ~65 bytes. I'm seeing close to 100 bytes. If I have 3 elements, it's using 150, 4 -> 200, etc all the way up to around 40 elements as it seems to hit the 2KB limit and starts compressing the data.
I don't see why it's using 50 bytes per element. There should be just one 24 byte header for the array, not one per element Anders On Tue, Oct 22, 2024 at 6:34 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Erik Sjoblom <sjoblo...@gmail.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 >
