On 2/20/07, Tom Lane <[EMAIL PROTECTED]> wrote:
"Pavan Deolasee" <[EMAIL PROTECTED]> writes: > ... Yes. The HOT-updated status of the root and all intermediate > tuples is cleared and their respective ctid pointers are made > point to themselves. Doesn't that destroy the knowledge that they form a tuple chain? While it might be that no one cares any longer, it would seem more reasonable to leave 'em chained together.
I see your point, but as you mentioned do we really care ? The chain needs to be broken so that the intermediate DEAD tuples can be vacuumed. We can't vacuum them normally because they could be a part of live HOT-update chain. Resetting the HOT-updated status of the root tuple helps to mark the index entry LP_DELETE once the entire HOT-update chain is dead. Also, if we decide to reuse the heap-only tuples without even vacuuming, breaking the chain is a better option since we then guarantee no references to the heap-only DEAD tuples. Thanks, Pavan -- EnterpriseDB http://www.enterprisedb.com
