---In firebird-support@yahoogroups.com, <michkurc@...> wrote : Hi, > fb 2.5.7.27050_0_x64 > fb 3.0.1.32609_0_x64 > > same table and data: > ... > > select count(*) from t1 > > //FB 2.5 time 4 sec. > //FB 3.0 time 6 sec > > //now select first 1 mln recs order by id desc > > select first 1000000 * from t1 order by id desc > > //FB 2.5 time 11 sec > //FB 3.0 time 1 min 54 sec.
The main question - where selected records was directed to ? I.e. you select 1 mln records and where do you store it ? Show on console ? It will be sloooow and doesn't depend on Firebird at all. I run this in isql (note "output null" below): a) 2.5.7.27038 SQL> set plan; SQL> set stat; SQL> output null; SQL> select count(*) from t1; PLAN (T1 NATURAL) Current memory = 9395256 Delta memory = 124384 Max memory = 9465760 Elapsed time= 2.40 sec Buffers = 2048 Reads = 151770 Writes 0 Fetches = 20303446 SQL> select first 1000000 * from t1 order by id desc; PLAN SORT ((T1 NATURAL)) Current memory = 9396336 Delta memory = 1080 Max memory = 71268832 Elapsed time= 10.58 sec Buffers = 2048 Reads = 151591 Writes 0 Fetches = 20303022 b) 3.0.1.32609 SQL> set plan; SQL> set stat; SQL> output null; SQL> select count(*) from t1; PLAN (T1 NATURAL) Current memory = 10928296 Delta memory = 251424 Max memory = 10997848 Elapsed time= 3.311 sec Buffers = 2048 Reads = 151821 Writes = 0 Fetches = 20303499 SQL> select first 1000000 * from t1 order by id desc; PLAN SORT (T1 NATURAL) Current memory = 10929000 Delta memory = 704 Max memory = 73851528 Elapsed time= 12.710 sec Buffers = 2048 Reads = 151621 Writes = 0 Fetches = 20303049 c) 3.0.2.32691 SQL> set plan; SQL> set stat; SQL> output null; SQL> select count(*) from t1; PLAN (T1 NATURAL) Current memory = 11024632 Delta memory = 251424 Max memory = 11094184 Elapsed time= 2.390 sec Buffers = 2048 Reads = 151821 Writes = 1 Fetches = 10606295 SQL> select first 1000000 * from t1 order by id desc; PLAN SORT (T1 NATURAL) Current memory = 11025336 Delta memory = 704 Max memory = 73947864 Elapsed time= 11.653 sec Buffers = 2048 Reads = 151621 Writes = 0 Fetches = 10605902 Regards, Vlad
