On 2/21/07, Simon Riggs <[EMAIL PROTECTED]> wrote:

I very much like Hannu's idea, but it does present some issues.

I too liked Hannu's idea initially, but Tom raised a valid concern
that it does not address the basic issue of root tuples. According
to the idea, a DEAD root tuple can be used for a subsequent
update of the same row. For a very large table, even if its updated
frequently, it is not unlikely that the same row might not be updated
for a long time. Even when the update happens we would be
constrained by the length of the new version being same or less
than the root tuple OR ability to perform retail-vacuum of the block.

Did you or anybody else got a chance to think about the other idea
I proposed of having indirection from the root line pointer ? As I
mentioned earlier, I myself haven't thought through it completely,
but at the face of it, it looks doable. It would add a four-byte
overhead per live tuple-chain, but IMHO would be much simpler
to implement and not too invasive.



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