>> Sweep work in this way or such different? If yes i should see many reads and
>> > only few writes to disk but this not happend. I see >1TB writes to disc
>> > for db size 52.74GB.
>> >
>I think the key issue that Karol is pointing to is the ratio of Disk IO writes
>to the number of pages (size of database). I agree with him.
>
>Even if there are off-page changes, these could be collected into a page group
>and written to disk as a group (since all of the extra pages are only related
>to the single original page).
As any regular DB access sweep collects pages in groups. But no matter of it
I'm absolutely not surprised with such ratio. When record on a data page is
garbage collected a lot of other pages are touched - indices for example. And
as long as we do not expect removed versions on a page to be in index order
number of index pages modified (and therefore written) is equal to the number
of removed versions with different index key values. I.e. ratio == 20 is quite
possible.
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