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. Thanks, Pavan -- EnterpriseDB http://www.enterprisedb.com