On Sat, Mar 17, 2012 at 8:48 PM, HuangQi <huangqiyx@gmail.com> wrote:
> About the second topic, so currently TABLESAMPLE is not implemented
> inside Postgres? I didn't see this query before, but I googled it just now
> and the query seems very weird and
> interesting. http://www.fotia.co.uk/fotia/DY.18.TheTableSampleClause.aspx
> Still, do you have any mail thread talking about this?
I think there may be a few, but there's a nice implementation plan
discussed by Neil Conway and written into slides from a few years ago:
http://www.pgcon.org/2007/schedule/attachments/9-Introduction_to_Hacking_PostgreSQL_Neil_Conway.pdf
He also had his implementation, although at this point some of the
bitrot will be intense:
http://www.neilconway.org/talks/hacking/
I also seem to remember writing this (to some degree) as a student as
part of a class project, so a full-blown production implementation in
a summer sounds reasonable, unless someone has thought more about this
and ran into some icebergs. I'm not sure exactly what the blockers
were to this being committed back in 2007 (not to suggest there
weren't any).
I haven't thought enough about skipscan, but there a number more
unknowns there to me...
--
fdr