recreate table tmp(id int primary key, x int, y int, z int);
commit;
create index tmp_x on tmp(x);
create index tmp_y on tmp(y);
create index tmp_z on tmp(z);
commit;
recreate global temporary table gtt(id int primary key, x int, y int, z int) on commit delete rows;
commit;
create index gtt_x on gtt(x);
create index gtt_y on gtt(y);
create index gtt_z on gtt(z);
commit;

set term ^;
execute block as
  declare n int = 500000;
  declare i int = 0;
begin
  while(i<n) do
      insert into tmp values( :i, rand()*10, rand()*100, rand()*1000 )
      returning :i+1 into i;
end
^
set term ;^
rollback;

set term ^;
execute block as
  declare n int = 500000;
  declare i int = 0;
begin
  while(i<n) do
      insert into gtt values( :i, rand()*10, rand()*100, rand()*1000 )
      returning :i+1 into i;
end
^
set term ;^
rollback;

2014-10-21T01:49:19.5090 (14037:0x7f3fb28069e0) EXECUTE_STATEMENT_FINISH
        oltp25 (ATT_1694, SYSDBA:NONE, NONE, TCPv4:192.168.43.96)
        C:\MIX\firebird\fb25\bin\isql.exe:924
                (TRA_158013, CONCURRENCY | WAIT | READ_WRITE)

Statement 39:
-------------------------------------------------------------------------------
execute block as
  declare n int = 500000;
  declare i int = 0;
begin
  while(i<n) do
      insert into tmp values( :i, rand()*10, rand()*100, rand()*1000 )
      returning :i+1 into i;
end

0 records fetched
  23473 ms, 6187 read(s), 5269 write(s), 19024610 fetch(es), 5511466 mark(s)

Table                             Natural     Index    Update    Insert    Delete   Backout     Purge   Expunge
***************************************************************************************************************
TMP                                                              500000               500000 

2014-10-21T01:49:19.5100 (14037:0x7f3fb28069e0) ROLLBACK_TRANSACTION
        oltp25 (ATT_1694, SYSDBA:NONE, NONE, TCPv4:192.168.43.96)
        C:\MIX\firebird\fb25\bin\isql.exe:924
                (TRA_158013, CONCURRENCY | WAIT | READ_WRITE)
      0 ms, 1 read(s), 2 write(s), 1 fetch(es), 1 mark(s)

2014-10-21T01:47:29.7440 (14037:0x7f3fb28069e0) EXECUTE_STATEMENT_FINISH
        oltp25 (ATT_1694, SYSDBA:NONE, NONE, TCPv4:192.168.43.96)
        C:\MIX\firebird\fb25\bin\isql.exe:924
                (TRA_158012, CONCURRENCY | WAIT | READ_WRITE)

Statement 38:
-------------------------------------------------------------------------------
execute block as
  declare n int = 500000;
  declare i int = 0;
begin
  while(i<n) do
      insert into gtt values( :i, rand()*10, rand()*100, rand()*1000 )
      returning :i+1 into i;
end

0 records fetched
  14265 ms, 5 read(s), 6360 write(s), 7537530 fetch(es), 2529897 mark(s)

Table                             Natural     Index    Update    Insert    Delete   Backout     Purge   Expunge
***************************************************************************************************************
RDB$INDICES                                      16
GTT                                                              500000

2014-10-21T01:47:29.7460 (14037:0x7f3fb28069e0) ROLLBACK_TRANSACTION
        oltp25 (ATT_1694, SYSDBA:NONE, NONE, TCPv4:192.168.43.96)
        C:\MIX\firebird\fb25\bin\isql.exe:924
                (TRA_158012, CONCURRENCY | WAIT | READ_WRITE)
      2 ms, 257 read(s), 3 write(s), 7577 fetch(es), 5685 mark(s)