On Wed, Jan 4, 2017 at 4:35 PM, Amit Kapila <amit.kapil...@gmail.com> wrote:
> In this new system, I
> think we can't remove undo entries of heap page till we clear
> corresponding index entries. I think we need to somehow collect the
> old values from undo corresponding to index and then scan the index
> remove the index entry and after that corresponding undo entry can be
> removed.

Do we really need to keep undo for heap until index entry is not
removed? IIUC, we anyway need to revalidate the index key with heap
tuple. What I am trying the say is that if we no longer needed UNDO
for the heap page (e.g because of rollback) then we can apply the UNDO
and remove it. I agree that there will be multiple index entries will
be pointing to this tuple, but only one of them can pass the key
revalidation with the heap. isn't it?

Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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