Re: GiST rtree logic is not right

Oleg Bartunov <oleg@sai.msu.su> writes:
> something is broken in HEAD. I recall it worked in STABLE, here is what I have

No, actually it is broken in 8.0 too.  The difference is that 8.0
defaults to not using an indexscan for this query.  In 8.0 I see:

regression=# set enable_seqscan TO 1;
SET
regression=# explain select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';
         QUERY PLAN
 
---------------------------------------------------------------------Aggregate  (cost=65.53..65.53 rows=1 width=0)  ->
SeqScan on gist_emp4000  (cost=0.00..64.75 rows=310 width=0)        Filter: (home_base <<
'(35565,5404),(35546,5360)'::box)
(3 rows)

regression=# select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';count
------- 2214
(1 row)

regression=# set enable_seqscan TO 0;
SET
regression=# explain select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';
                   QUERY PLAN
 
----------------------------------------------------------------------------------------Aggregate  (cost=112.96..112.96
rows=1width=0)  ->  Index Scan using grect2ind on gist_emp4000  (cost=0.00..112.18 rows=310 width=0)        Index Cond:
(home_base<< '(35565,5404),(35546,5360)'::box)
 
(3 rows)

regression=# select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';count
------- 2144
(1 row)

In CVS tip the default plan is:

regression=# explain select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';
               QUERY PLAN
 
--------------------------------------------------------------------------------Aggregate  (cost=35.74..35.74 rows=1
width=0) ->  Bitmap Heap Scan on gist_emp4000  (cost=5.08..34.96 rows=310 width=0)        Recheck Cond: (home_base <<
'(35565,5404),(35546,5360)'::box)       ->  Bitmap Index Scan on grect2ind  (cost=0.00..5.08 rows=310 width=0)
   Index Cond: (home_base << '(35565,5404),(35546,5360)'::box)
 
(5 rows)

regression=# select count(*) from gist_emp4000 where home_base << '(35565,5404),(35546,5360)';count
------- 2144
(1 row)
        regards, tom lane