Re: Polyphase Merge

On Mon, Jan 21, 2008 at 07:42:24PM +0100, mac_man2005(at)hotmail(dot)it wrote:
> During run creations I use two heaps instead of just one (yeah,
> it's still me... the one of the two heaps still trying to get some
> answer/help from -hackers)

Hi again!

> ISSUES
> a) how to distribute logical runs (that is both of its physical runs)
> into tapes?
> b) one of the 2 physical runs of the logical run is to be red upside
> down while merging: how to efficiently do it?

It's really up to you to find answers to these questions, especially
the first one. Once you've designed an efficient algorithm then the
second point (which I'm interpreting as how you'd go about changing
tuplestore(?) so that things can be read in reverse order) should
just drop out as an implementation detail :) I'm guessing you'll
end up not reading the store in reverse order but arranging things
differently---it'll be interesting to see.

What does your current code look like and how have you solved it there?
If you've already written it then you'll need to be much more specific
with your questions about integrating it into PG.

Sam