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https://issues.apache.org/jira/browse/OPENJPA-2416?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Andreas Mader updated OPENJPA-2416:
-----------------------------------

    Description: 
We are using OpenJPA with Oracle 11g Database. For Paging we use setFirstResult 
and setMaxResults to Page through the result set.

Lets take an example: PageSize 25.

first Statement: firstResult: 0; maxResults: 26 (1 more to check if it is 
truncated)
SQL generated: 
SELECT * FROM ([my statement]) WHERE ROWNUM <= 26

second Statement: firstResult: 25; maxResults: 26
SQL generated: 
SELECT * FROM (SELECT r.*, ROWNUM RNUM FROM ([my statement]) r WHERE ROWNUM <= 
50) WHERE RNUM > 25

The way limiting the resultset for paging is sometimes not correct. The last 
result of the statement should be equal to the first result of the new page - 
but it isn't always. If the sorting is done on a non-unique column in the 
database, there are different sortings in the resultset in these two 
statements. I don't know why it is done this way, I would prefer the following 
statement (this works for all values of firstResult and maxResults with 
non-unique sort column):

SELECT outer.* FROM (
  SELECT ROWNUM rn, inner.* FROM 
     ([my statement])
  inner)
outer WHERE outer.rn > 25 AND outer.rn <= 50


  was:
We are using OpenJPA with Oracle 11g Database. For Paging we use setFirstResult 
and setMaxResults to Page through the result set.

Lets take an example: PageSize 25.

first Statement: firstResult: 0; maxResults: 26 (1 more to check if it is 
truncated)
SQL generated: 
SELECT * FROM ([my statement]) WHERE ROWNUM <= 26

second Statement: firstResult: 25; maxResults: 26
SQL generated: 
SELECT * FROM (SELECT r.*, ROWNUM RNUM FROM ([my statement]) r WHERE ROWNUM <= 
50) WHERE RNUM > 25

The way limiting the resultset for paging is sometimes not correct. The last 
result of the statement should be equal to the first result of the new page - 
but it isn't always. If the sorting is done on a non-unique column in the 
database, there are different sortings in the resultset in these two 
statements. I don't know why it is done this way, I would prefer the following 
statement (this works for all values of _firstResult_ and _maxResults_ with 
non-unique sort column):

SELECT outer.* FROM (
  SELECT ROWNUM rn, inner.* FROM 
     ([my statement])
  inner)
outer WHERE outer.rn > 25 AND outer.rn <= 50


    
> setFirstResult/setMaxResults (Paging) with Oracle
> -------------------------------------------------
>
>                 Key: OPENJPA-2416
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-2416
>             Project: OpenJPA
>          Issue Type: Improvement
>          Components: query
>    Affects Versions: 2.1.1
>            Reporter: Andreas Mader
>
> We are using OpenJPA with Oracle 11g Database. For Paging we use 
> setFirstResult and setMaxResults to Page through the result set.
> Lets take an example: PageSize 25.
> first Statement: firstResult: 0; maxResults: 26 (1 more to check if it is 
> truncated)
> SQL generated: 
> SELECT * FROM ([my statement]) WHERE ROWNUM <= 26
> second Statement: firstResult: 25; maxResults: 26
> SQL generated: 
> SELECT * FROM (SELECT r.*, ROWNUM RNUM FROM ([my statement]) r WHERE ROWNUM 
> <= 50) WHERE RNUM > 25
> The way limiting the resultset for paging is sometimes not correct. The last 
> result of the statement should be equal to the first result of the new page - 
> but it isn't always. If the sorting is done on a non-unique column in the 
> database, there are different sortings in the resultset in these two 
> statements. I don't know why it is done this way, I would prefer the 
> following statement (this works for all values of firstResult and maxResults 
> with non-unique sort column):
> SELECT outer.* FROM (
>   SELECT ROWNUM rn, inner.* FROM 
>      ([my statement])
>   inner)
> outer WHERE outer.rn > 25 AND outer.rn <= 50

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