SQL INDEX TUNING

Question

Hi,
I am having a table with proper index. While selecting query, some time index is taken and some time table access full going on.
The table having following columns
Acc Id - Number
Account key = Number
Account Number - Varchar2(25)
Account Date - Date
Inst No - Number
Type Code - Varchar2(1).
Few more colums are there
The following indexes are there in the table
1. Acc ID - Primary Key
2. Account Key, trunc(account date) - Function based index
3. Account Key, type code - Normal Index
4. Inst No - Normal Index
Query
select * from ptable
where account_key = 128
and trunc(account_date) <= '30-apr-2008'
Trace is showing full table access and trace is given below.
recursive calls     78
db block gets     0
consistent gets     150
physical reads     0
redo size     0
bytes sent via SQL*Net to client     11577
bytes received via SQL*Net from client     671
SQL*Net roundtrips to/from client     2
sorts (memory)     1
sorts (disk)     0
If I change the date as '30-apr-0008', then the index is considered
recursive calls     78
db block gets     0
consistent gets     133
physical reads     0
redo size     0
bytes sent via SQL*Net to client     2525
bytes received via SQL*Net from client     671
SQL*Net roundtrips to/from client     2
sorts (memory)     1
sorts (disk)     0
Due to this my query is very slow. If i use the hint, index is considered.
What would be the reason for this. Whether I have to use always 'Hint'.
Oracle version - 10g R2

Answer 1

Hi,
Thanks for your information. I have already taken tkprof and analyze the query explain plan. I am not able to understand why it's reacting like. Here with I have enclosed explain plan and tkprof
Plan hash value: 1680079810
| Id | Operation           | Name                | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT      |                | 52789 | 11M | 669 (2) | 00:00:09 |
|* 1 | TABLE ACCESS FULL     | PS_TB_BRS_BANK_BOOK | 52789 | 11M | 669 (2) | 00:00:09 |
Predicate Information (identified by operation id):
1 - filter("BANK_ACCOUNT_KEY"=128 AND
TRUNC(INTERNAL_FUNCTION("VOUCHER_DATE"))<=TO_DATE('2008-04-30 00:00:00',
'yyyy-mm-dd hh24:mi:ss'))
Tkprof
Select Bank_Book_Id, Null Value_Date, Null Bank_Statement_Date, Voucher_Date,
Instrument_No "Key Column",Credit_Amount
From
Ps_Tb_Brs_Bank_Book Where Bank_Account_Key = 128 And Trunc(Voucher_Date) <=
'30-APR-08' And Brs_Match_Type_Code In ('U','P') And Instrument_No =
:G_Match And Instrument_No Is Not Null And Credit_Amount > 0
call count cpu elapsed disk query current rows
Parse 42140 0.70 0.83 0 0 0 0
Execute 42140 0.92 0.83 0 39 0 0
Fetch 45644 2046.39 1998.53 125604955 127350518 0 3504
total 129924 2048.03 2000.20 125604955 127350557 0 3504
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: 38 (recursive depth: 1)
Rows Row Source Operation
0 TABLE ACCESS FULL PS_TB_BRS_BANK_BOOK (cr=3022 pr=2991 pw=0 time=51518 us)
Provide necessary guidelines to trace this.
Regards