Hello. How to use tid scans? This below not works :-( Always is used merge join. DROP TABLE IF EXISTS test1; CREATE TABLE test1 as select i,hashint4(i)::text from generate_series(1,10000) as a(i); DROP TABLE IF EXISTS test2; CREATE TABLE test2 as select j,j%10000 as i,null::tid as ct from generate_series(1,1000000) as a(j); UPDATE test2 SET ct=test1.ctid FROM test1 WHERE test2.i=test1.i; VACUUM ANALYZE test1; VACUUM ANALYZE test2; SET enable_tidscan = true; SELECT * FROM test1 join test2 on(test1.ctid=test2.ct) ------------------------ Explain analyze ------------------------ "Merge Join (cost=249703.68..283698.78 rows=1999633 width=28) (actual time=7567.582..19524.865 rows=999900 loops=1)" " Output: test1.i, test1.hashint4, test2.j, test2.i, test2.ct" " Merge Cond: (test2.ct = test1.ctid)" " -> Sort (cost=248955.55..253955.30 rows=1999900 width=14) (actual time=7513.539..10361.598 rows=999901 loops=1)" " Output: test2.j, test2.i, test2.ct" " Sort Key: test2.ct" " Sort Method: external sort Disk: 23456kB" " -> Seq Scan on test2 (cost=0.00..16456.80 rows=1999900 width=14) (actual time=0.551..2234.130 rows=1000000 loops=1)" " Output: test2.j, test2.i, test2.ct" " -> Sort (cost=748.14..773.14 rows=10000 width=20) (actual time=54.020..2193.688 rows=999901 loops=1)" " Output: test1.i, test1.hashint4, test1.ctid" " Sort Key: test1.ctid" " Sort Method: quicksort Memory: 960kB" " -> Seq Scan on test1 (cost=0.00..83.75 rows=10000 width=20) (actual time=0.030..26.205 rows=10000 loops=1)" " Output: test1.i, test1.hashint4, test1.ctid" "Total runtime: 21635.881 ms" ------------ pasman -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
