Sequence order and index scan

Question

1)If i miss the sequence while importing tables how can i restore the correct sequence value for that particular column of that table.
2) I created 2 indexes for a table the table is big around 3 gb.The indexes also around 1.3 and 1 gb each.when i am trying to use select count(*) from table_name it takes long time to get the result.If i am using witout indexes it is giving fast result than previous.Why this is happening.If i drop the indexes whehter it will give more performance.This is oracle 7.3.4 on soalris 7.How can i avoid the index scan any hints to use full tablescan
with regards
ramya

Answer 1

FULL hint:
SQL> set autotrace traceonly explain
SQL> select * from emp e where empno = 12 ;
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=1 Bytes=41)
   1    0   FILTER
   2    1     TABLE ACCESS (BY INDEX ROWID) OF 'EMP' (Cost=2 Card=1 Bytes=41)
   3    2       INDEX (UNIQUE SCAN) OF 'PK_EMP' (UNIQUE)
SQL> select /*+ FULL(e) */ * from emp e where empno = 12 ;
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=1 Bytes=41)
   1    0   FILTER
   2    1     TABLE ACCESS (FULL) OF 'EMP' (Cost=2 Card=1 Bytes=41)
SQL> disconnect
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production
SQL>