recreate global temporary table tmp$buf( doc_id bigint ) on commit delete rows;

SQL> commit; set transaction no auto undo;
SQL> insert into tmp$buf(doc_id) select 1 from rdb$types rows 10; -- 1
SQL> delete from tmp$buf;                                         -- 2
SQL> insert into tmp$buf(doc_id) select 1 from rdb$types rows 10; -- 3
SQL> delete from tmp$buf;                                         -- 4
SQL> insert into tmp$buf(doc_id) select 1 from rdb$types rows 10; -- 5
SQL> delete from tmp$buf;                                         -- 6
SQL> insert into tmp$buf(doc_id) select 1 from rdb$types rows 10; -- 7
SQL> delete from tmp$buf;                                         -- 8

      0 ms, 54 fetch(es), 10 mark(s)
      0 ms, 74 fetch(es), 10 mark(s)
      0 ms, 94 fetch(es), 10 mark(s)
      0 ms, 114 fetch(es), 10 mark(s)