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