Re: vacuum internals and performance affect

thx a lot for your answer :)

so when a transaction is still open from a while back (according to the
transactionID), no 'new dead' tuples can be marked as re-usable space for
new rows, right? by 'new dead' i mean that for example there is a
transaction running from 10.00am(with a specific transactionID). when i
delete rows at 11.00am these are the ones i am referring to.

the same thing happens with the index, right? the dead enties for the rows
that were deleted at 11.00am cannot be removed yet (this is not based on the
timestamp, i get it, i just want to point out that due to MVCC these rows
should be visible to the old transaction and by using timestamps this is
more obvious)

but, for these rows, the 'deleted' ones. does vacuum do anything at all at
that time? and if so, what is it? thx in advance

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