Re: synchronized scans for VACUUM

Gregory Stark <stark@enterprisedb.com> writes:
>> It will certainly not "solve" the problem.  What it will do is mean that
>> the breaks are further apart and longer, which seems to me to make the
>> conflict with syncscan behavior worse not better.

> How would it make them longer? They still have the same amount of i/o to do
> scanning the indexes. I suppose they would dirty more pages which might slow
> them down?

More tuples to delete = more writes (in WAL, if not immediately in the
index itself) = longer to complete the indexscan.  It's still cheaper
than doing multiple indexscans, of course, but my point is that the
index-fixing work gets concentrated.
        regards, tom lane