On Fri, Sep 2, 2011 at 12:45 PM, Tom Lane t...@sss.pgh.pa.us wrote:
column values). But GROUP BY or DISTINCT would entirely invalidate the
column frequency statistics, which makes me think that ignoring the
pg_statistic entry might be the thing to do. Comments?
There's a possible problem
I wrote:
On a longer-term basis, I'm looking into what we could do with
extracting stats from subqueries, but that doesn't seem like material
for a backpatch. I have a draft patch that I've been playing with
(attached).
I've committed a heavily rewritten version of that patch. Git HEAD
Peter Eisentraut pete...@gmx.net writes:
On lör, 2011-08-27 at 13:32 -0400, Tom Lane wrote:
The larger problem is that if a subquery didn't get flattened, it's
often because it's got LIMIT, or GROUP BY, or some similar clause that
makes it highly suspect whether the statistics available for
On lör, 2011-08-27 at 13:32 -0400, Tom Lane wrote:
EXPLAIN SELECT * FROM test1 WHERE sha1 in (SELECT sha1 FROM test2
LIMIT 200);
Here, however, it has apparently not passed this knowledge through
the
LIMIT.
The LIMIT prevents the subquery from being flattened entirely, ie we
don't
On Wed, Aug 31, 2011 at 6:22 AM, Peter Eisentraut pete...@gmx.net wrote:
On lör, 2011-08-27 at 13:32 -0400, Tom Lane wrote:
EXPLAIN SELECT * FROM test1 WHERE sha1 in (SELECT sha1 FROM test2
LIMIT 200);
Here, however, it has apparently not passed this knowledge through
the
LIMIT.
The
Robert Haas robertmh...@gmail.com writes:
On Wed, Aug 31, 2011 at 6:22 AM, Peter Eisentraut pete...@gmx.net wrote:
I liked the old one better. ;-)
AFAICS, those plans are identical, except for a minor difference in
the cost of scanning test2.
The point is that the estimate of the result size
On Sat, Aug 27, 2011 at 1:32 PM, Tom Lane t...@sss.pgh.pa.us wrote:
Peter Eisentraut pete...@gmx.net writes:
EXPLAIN SELECT * FROM test1 WHERE sha1 in (SELECT sha1 FROM test2);
QUERY PLAN
--
Peter Eisentraut pete...@gmx.net writes:
EXPLAIN SELECT * FROM test1 WHERE sha1 in (SELECT sha1 FROM test2);
QUERY PLAN
--
Hash Semi Join (cost=30.52..61.27 rows=1000 width=27)
Hash Cond:
