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
Erik Sjoblom <sjoblom65@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?
