Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> Yes, as Tom points out, this must be done with bias away from the
>> very end of the table.
>
>> I meant that we should start from the beginning of large spaces and
>> that we shouldn't assume that all space worth filling is at start
>> of relation.
OK, so I did misunderstand you; we agree after all. :-)
> So for example we might try resetting the search to the start of the
> relation with probability 0.01.
If I understand the heuristic you propose, and my math skill haven't
eroded too badly from lack of use, every 229 spots considered would
cause a 90% chance of reset. That means that the odds of getting past
50,000 spots (the number of pages with available free space at which I
generally start to get worried) without resetting is about 1 in 10^218
-- which is a risk I'm willing to accept. ;-)
-Kevin