Question

I had to copy the data from oracle tables to files.

I have a join query which fetches 800k records so i used row_number() function along with order by clause to generate 4 files containing 200k each.

Query :

SELECT * FROM (
    SELECT  ROW_NUMBER() OVER ( order by FILE_KEY desc ) rn,
        FILE_KEY, ROUTING_NO, INTLROUT_TYPE, ABBR_COUNTRY_CODE_2D, HO_CATALOG_NO 
    FROM BANK_INTL_ROUT_TBL rout, BANK_INTL_LOC_TBL loc 
    WHERE loc.CATALOG_NO = rout.FILE_KEY) 
WHERE rn BETWEEN start AND end;

Parameters:

For 1st File  : start =1 ,end = 200000
For 2nd File  : start =200001 ,end = 400000
For 3rd File  : start =400001 ,end = 600000
For 4th File  : start =600001 ,end = 800000

But when i checked last 10 row using this query in sql query browser and last 10 rows of file are different that is sequence is different in file and sql query browser.

SELECT * FROM (
    SELECT  ROW_NUMBER() OVER(  order by FILE_KEY desc ) rn,
        FILE_KEY,ROUTING_NO,INTLROUT_TYPE,ABBR_COUNTRY_CODE_2D,HO_CATALOG_NO 
    FROM BANK_INTL_ROUT_TBL rout, BANK_INTL_LOC_TBL loc 
    WHERE loc.CATALOG_NO=rout.FILE_KEY) 
WHERE rn BETWEEN 709990 AND 80000;

Answer 1

This can be because you have something like this

row_number file_key 
799998     same_number
799999     same_number
800000     same_number
800001     same_number
800002     same_number
800003     same_number
800004     same_number

because you order by file_key.

How do you observed that are different data? from your other columns. So, you can use:

SELECT  ROW_NUMBER() OVER(order by FILE_KEY desc, ROUTING_NO, INTLROUT_TYPE, ABBR_COUNTRY_CODE_2D, HO_CATALOG_NO ) rn

Or(second cause), your base table had been changen between your querys.

UDPDATE: you can use the use_hash hint to speed up your query. 5 hours is too much for this query.

SELECT * FROM (
    SELECT  /*+use_hash(rout loc)*/
        ROW_NUMBER() OVER(order by FILE_KEY desc, ROUTING_NO, INTLROUT_TYPE, ABBR_COUNTRY_CODE_2D, HO_CATALOG_NO ) rn,
        FILE_KEY, ROUTING_NO, INTLROUT_TYPE, ABBR_COUNTRY_CODE_2D, HO_CATALOG_NO 
    FROM BANK_INTL_ROUT_TBL rout, BANK_INTL_LOC_TBL loc 
    WHERE loc.CATALOG_NO = rout.FILE_KEY) 
WHERE rn BETWEEN start AND end;