On Mon, Jan 21, 2008 at 04:13:32PM -0500, Tom Lane wrote: > Sam Mason <[EMAIL PROTECTED]> writes: > > 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. > > I agree --- having to read the run back from external storage, only to > write it out again with no further useful work done on it, sounds like > a guaranteed loser.
Manolo's idea (wherever it came from) will generate longer runs in some specific non-random data distributions (i.e. hopefully real life), but it'll obviously only be a net win if this is offset by not having to do any extra work reordering data. It would be great if it could be got to work! > To make this work you'll need some kind of ju-jitsu > rearrangement that logically puts the run where it needs to go without > physically moving any data. yup, that's the fun part :) Sam ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
