Need help in optimizing the query with joins and group by clause

Question

I am having problem in executing the query below.. it is taking lot of time. To simplify, I have added the two tables FILE_STATUS = stores the file load details and COMM table that is actual business commission table showing records successfully processed and which records were transmitted to other system. Records with status = T is trasnmitted to other system and traansactions with P is pending.
CREATE TABLE FILE_STATUS
(FILE_ID VARCHAR2(14),
FILE_NAME VARCHAR2(20),
CARR_CD VARCHAR2(5),
TOT_REC NUMBER,
TOT_SUCC NUMBER);
CREATE TABLE COMM
(SRC_FILE_ID VARCHAR2(14),
REC_ID NUMBER,
STATUS CHAR(1));
INSERT INTO FILE_STATUS VALUES ('12345678', 'CM_LIBM.TXT', 'LIBM', 5, 4);
INSERT INTO FILE_STATUS VALUES ('12345679', 'CM_HIPNT.TXT', 'HIPNT', 4, 0);
INSERT INTO COMM VALUES ('12345678', 1, 'T');
INSERT INTO COMM VALUES ('12345678', 3, 'T');
INSERT INTO COMM VALUES ('12345678', 4, 'P');
INSERT INTO COMM VALUES ('12345678', 5, 'P');
COMMIT;Here is the query that I wrote to give me the details of the file that has been loaded into the system. It reads the file status and commission table to show file name, total records loaded, total records successfully loaded to the commission table and number of records that has been finally transmitted (status=T) to other systems.
SELECT
    FS.CARR_CD
    ,FS.FILE_NAME
    ,FS.FILE_ID
    ,FS.TOT_REC
    ,FS.TOT_SUCC
    ,NVL(C.TOT_TRANS, 0) TOT_TRANS
FROM FILE_STATUS FS
LEFT JOIN
    SELECT SRC_FILE_ID, COUNT(*) TOT_TRANS
    FROM COMM
    WHERE STATUS = 'T'
    GROUP BY SRC_FILE_ID
) C ON C.SRC_FILE_ID = FS.FILE_ID
WHERE FILE_ID = '12345678';In production this query has more joins and is taking lot of time to process.. the main culprit for me is the join on COMM table to get the count of number of transactions transmitted. Please can you give me tips to optimize this query to get results faster? Do I need to remove group and use partition or something else. Please help!

Answer 1

I get 2 rows if I use my query with your new criteria. Did you commit the record if you are using a second connection to query? Did you remove the criteria for file_id?
select carr_cd, file_name, file_id, tot_rec, tot_succ, tot_trans
  from (select fs.carr_cd,
               fs.file_name,
               fs.file_id,
               fs.tot_rec,
               fs.tot_succ,
               count(case
                        when c.status = 'T' then
                         1
                        else
                         null
                      end) over(partition by c.src_file_id) tot_trans,
               row_number() over(partition by c.src_file_id order by null) rn
          from file_status fs
          left join comm c
            on c.src_file_id = fs.file_id
         where carr_cd = 'LIBM')
where rn = 1;
CARR_CD FILE_NAME            FILE_ID           TOT_REC   TOT_SUCC  TOT_TRANS
LIBM    CM_LIBM.TXT          12345678                5          4          2
LIBM    CM_LIBM.TXT          12345677               10          0          0Using RANK can potentially produce multiple rows to be returned though your data may prevent this. ROW_NUMBER will always prevent duplicates. The ordering of the analytical function is irrelevant in your query if you use ROW_NUMBER. You can remove the outermost query and inspect the data returned by the inner query;
select fs.carr_cd,
       fs.file_name,
       fs.file_id,
       fs.tot_rec,
       fs.tot_succ,
       count(case
                when c.status = 'T' then
                 1
                else
                 null
              end) over(partition by c.src_file_id) tot_trans,
       row_number() over(partition by c.src_file_id order by null) rn
from file_status fs
left join comm c
on c.src_file_id = fs.file_id
where carr_cd = 'LIBM';
CARR_CD FILE_NAME            FILE_ID           TOT_REC   TOT_SUCC  TOT_TRANS         RN
LIBM    CM_LIBM.TXT          12345678                5          4          2          1
LIBM    CM_LIBM.TXT          12345678                5          4          2          2
LIBM    CM_LIBM.TXT          12345678                5          4          2          3
LIBM    CM_LIBM.TXT          12345678                5          4          2          4
LIBM    CM_LIBM.TXT          12345677               10          0          0          1