Help to Merge SQL into single

Question

Hi All,
I am using Oracle 11g. I have SQL Query which has two select clause and comibined using union clause.
Execution of query takes more time to run
Pls share me your ideas to merge into single SQL
SELECT t1.REC_ST,
       t1.VERSION_NO,
       t1.ROW_TS,
       t1.USER_ID,
       t1.EFFECTIVE_DT,
       t1.CREATE_DT,
       t1.MIN_INT_AMT,
       t1.ABSOLUTE_RATE,
       t1.WAIVER_AMT,
       t1.DRCR_IND,
       t1.INDEX_RATE_ID,
       t1.DEPOSIT_ACCT_INT_ID,
       t1.DEPOSIT_ACCT_ID,
       t1.OVR_FG,
       t1.ACCRUAL_BAL_BASIS_TY,
       t1.ACCRUAL_BASIS_TY,
       t1.MARGIN_RATE,
       t1.DEPOSIT_PROD_INT_ID,
       t1.MIN_RATE,
       t1.ACCRUAL_FREQ_VALUE,
       t1.ACCRUAL_FREQ_CD,
       t1.MAX_RATE,
       t1.RATE_STRUCT_CD,
       t1.INDEX_RATE,
       t1.DEPOSIT_ACCT_INT_HIST_ID,
       t1.MARGIN_TYPE_CD,
       t1.MARGIN_BAL_BASIS_TY,
       t1.INT_RATE_TY,
       t2.INDEX_NM AS INDEX_RATE_NM,
       NULL AS PROD_INT_HIST_ID
  FROM DP_ACCT_INTEREST_HISTORY t1,
       INDEX_RATE t2
WHERE t1.INDEX_RATE_ID = t2.INDEX_RATE_ID (+)
   AND t1.OVR_FG = 'Y'
UNION
SELECT t1.REC_ST,
       t1.VERSION_NO,
       t1.ROW_TS,
       t1.USER_ID,
       t1.EFFECTIVE_DT,
       t1.CREATE_DT,
       t1.MIN_INT_AMT,
       t1.ABSOLUTE_RATE,
       t1.WAIVER_AMT,
       t1.DRCR_IND,
       t1.INDEX_RATE_ID,
       t2.DEPOSIT_ACCT_INT_ID,
       t2.DEPOSIT_ACCT_ID,
       t2.OVR_FG,
       t1.ACCRUAL_BAL_BASIS_TY,
       t1.ACCRUAL_BASIS_TY,
       t1.MARGIN_RATE,
       t2.DEPOSIT_PROD_INT_ID,
       t1.MIN_RATE,
       t1.ACCRUAL_FREQ_VALUE,
       t1.ACCRUAL_FREQ_CD,
       t1.MAX_RATE,
       t1.RATE_STRUCT_CD,
       t1.INDEX_RATE,
       t1.PROD_INT_HIST_ID AS DEPOSIT_ACCT_INT_HIST_ID,
       t1.MARGIN_TYPE_CD,
       t1.MARGIN_BAL_BASIS_TY,
       t1.INT_RATE_TY,
       t3.INDEX_NM AS INDEX_RATE_NM,
       t1.PROD_INT_HIST_ID
  FROM PRODUCT_INTEREST_HISTORY t1,
       DEPOSIT_ACCOUNT_INTEREST t2,
       INDEX_RATE t3
WHERE t1.PROD_INT_ID = t2.DEPOSIT_PROD_INT_ID
   AND t2.OVR_FG = 'N'
   AND t1.INDEX_RATE_ID = t3.INDEX_RATE_ID (+)Thanks & Regards
Sami

Answer 1

Hi All,
Sorry i have missed out..
Explain Plan
Plan
SELECT STATEMENT  ALL_ROWSCost: 56,570  Bytes: 191,285,367  Cardinality: 1,188,177                         
    12 SORT UNIQUE  Cost: 56,570  Bytes: 191,285,367  Cardinality: 1,188,177                     
        11 UNION-ALL                 
            3 HASH JOIN RIGHT OUTER  Cost: 14,252  Bytes: 190,997,842  Cardinality: 1,186,322             
                1 TABLE ACCESS FULL TABLE BENCHMARK.INDEX_RATE Cost: 3  Bytes: 588  Cardinality: 28         
                2 TABLE ACCESS FULL TABLE BENCHMARK.DP_ACCT_INTEREST_HISTORY Cost: 14,243  Bytes: 166,085,080  Cardinality: 1,186,322         
            10 HASH JOIN  Cost: 135  Bytes: 287,525  Cardinality: 1,855             
                6 TABLE ACCESS BY INDEX ROWID TABLE BENCHMARK.DEPOSIT_ACCOUNT_INTEREST Cost: 126  Bytes: 10,800  Cardinality: 540         
                    5 BITMAP CONVERSION TO ROWIDS     
                        4 BITMAP INDEX SINGLE VALUE INDEX (BITMAP) BENCHMARK.DEP_ACCT_INT_OVR_FG_IDX
                9 HASH JOIN RIGHT OUTER  Cost: 9  Bytes: 60,750  Cardinality: 450         
                    7 TABLE ACCESS FULL TABLE BENCHMARK.INDEX_RATE Cost: 3  Bytes: 588  Cardinality: 28     
                    8 TABLE ACCESS FULL TABLE BENCHMARK.PRODUCT_INTEREST_HISTORY Cost: 5  Bytes: 51,300  Cardinality: 450      thanks & Regards
Sami