>Jean-Michel Pouré<jm@xxxxxxxxx> wrote:
> Does not show any result because of ROLLBACK;
Then you need to use a better tool to run it. For example, in psql:
test=# create table t2 (c1 int not null);
CREATE TABLE
test=# insert into t2 select * from generate_series(1,10000);
INSERT 0 10000
test=# create unique index t2_c1 on t2 (c1);
CREATE INDEX
test=# explain analyze select count(*) from t2 where c1 between 200 and
400;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------
Aggregate (cost=47.77..47.78 rows=1 width=0) (actual
time=0.668..0.669 rows=1 loops=1)
-> Bitmap Heap Scan on t2 (cost=4.76..47.64 rows=50 width=0)
(actual time=0.091..0.380 rows=201 loops=1)
Recheck Cond: ((c1 >= 200) AND (c1 <= 400))
-> Bitmap Index Scan on t2_c1 (cost=0.00..4.75 rows=50
width=0) (actual time=0.080..0.080 rows=201 loops=1)
Index Cond: ((c1 >= 200) AND (c1 <= 400))
Total runtime: 0.722 ms
(6 rows)
test=# begin transaction;
BEGIN
test=# drop index t2_c1;
DROP INDEX
test=# explain analyze select count(*) from t2 where c1 between 200 and
400;
QUERY PLAN
--------------------------------------------------------------------------------------------------------
Aggregate (cost=190.50..190.51 rows=1 width=0) (actual
time=3.324..3.325 rows=1 loops=1)
-> Seq Scan on t2 (cost=0.00..190.00 rows=200 width=0) (actual
time=0.053..3.036 rows=201 loops=1)
Filter: ((c1 >= 200) AND (c1 <= 400))
Total runtime: 3.366 ms
(4 rows)
test=# rollback transaction;
ROLLBACK
-Kevin
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