On Thu, Mar 1, 2012 at 12:39 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> I am starting to look at this patch now. I'm wondering exactly why the > decision was made to continue storing btree-style statistics for arrays, > in addition to the new stuff. The pg_statistic rows for array columns > tend to be unreasonably wide already, and as-is this patch will make > them quite a lot wider. I think it requires more than a little bit of > evidence to continue storing stats that seem to have only small > probability of usefulness. > > In particular, if we didn't store that stuff, we'd not need to widen the > number of columns in pg_statistic, which would noticeably reduce both > the footprint of the patch and the probability of breaking external > code. > Initially, I used existing slots for new statistics, but I've changed this after the first review: http://archives.postgresql.org/pgsql-hackers/2011-07/msg00780.php Probably, btree statistics really does matter for some sort of arrays? For example, arrays representing paths in the tree. We could request a subtree in a range query on such arrays. ------ With best regards, Alexander Korotkov.