SQL> create database "ttt04.fdb" pagesize  4096 ;
SQL> commit;
SQL> exit;

[firebird@firebird firebird]$ isql -c 65536 ttt04.fdb
Database:  ttt04.fdb

SQL> set stat off;
SQL> commit;
SQL> set echo off;
SQL> recreate table ttt(uid char(16) character set octets not null, primary key(uid));
commit;
set stat on;
set term ^;
execute block as
declare n int = 1000000;
begin
  while (n>0) do insert into ttt values(gen_uuid()) returning :n-1 into n;
end^
set term ;^
commit;
set stat off;
set echo on;

[firebird@firebird firebird]$ gstat -r -t TTT ttt04.fdb

Database "ttt04.fdb"
Database header page information:
        Flags                   0
        Checksum                12345
        Generation              13
        Page size               4096
        ODS version             11.2
        Oldest transaction      8
        Oldest active           9
        Oldest snapshot         9
        Next transaction        10
        Bumped transaction      1
        Sequence number         0
        Next attachment ID      2
        Implementation ID       24
        Shadow count            0
        Page buffers            0
        Next header page        0
        Database dialect        3
        Creation date           Nov 9, 2011 15:56:18
        Attributes              force write

    Variable header data:
        *END*


Database file sequence:
File ttt.fdb is the only file

Analyzing database pages ...
TTT (128)
    Primary pointer page: 165, Index root page: 166
    Average record length: 21.00, total records: 1000000
    Average version length: 0.00, total versions: 0, max versions: 0
    Data pages: 15152, data page slots: 15152, average fill: 62%
    Fill distribution:
         0 - 19% = 0
        20 - 39% = 1
        40 - 59% = 0
        60 - 79% = 15151
        80 - 99% = 0

    Index RDB$PRIMARY1 (0)
        Depth: 3, leaf buckets: 7360, nodes: 1000000
         Average data length: 14.05 , total dup: 0, max dup: 0
        Fill distribution:
             0 - 19% = 70
            20 - 39% = 3
            40 - 59% = 2434
            60 - 79% = 3044
            80 - 99% = 1809

 [code=plaintext]set stat off;
commit;
set echo off;
--recreate table ttt(uid char(16) character set octets not null, primary key(uid));
recreate table ttt(id int primary key);
commit;
set stat on;
set term ^;
execute block as
declare n int = 1000000;
begin
  --while (n>0) do insert into ttt values(gen_uuid()) returning :n-1 into n;
  while (n>0) do insert into ttt values(:n) returning :n-1 into n;
end^
set term ;^
commit;
set stat off;
set echo on;