Author: arminw
Date: Wed Mar 21 18:22:31 2007
New Revision: 521071
URL: http://svn.apache.org/viewvc?view=rev&rev=521071
Log:
add comment
Modified:
db/ojb/trunk/src/java/org/apache/ojb/broker/platforms/PlatformDb2Impl.java
Modified:
db/ojb/trunk/src/java/org/apache/ojb/broker/platforms/PlatformDb2Impl.java
URL:
http://svn.apache.org/viewvc/db/ojb/trunk/src/java/org/apache/ojb/broker/platforms/PlatformDb2Impl.java?view=diff&rev=521071&r1=521070&r2=521071
==============================================================================
--- db/ojb/trunk/src/java/org/apache/ojb/broker/platforms/PlatformDb2Impl.java
(original)
+++ db/ojb/trunk/src/java/org/apache/ojb/broker/platforms/PlatformDb2Impl.java
Wed Mar 21 18:22:31 2007
@@ -276,15 +276,57 @@
return false;
}
- public StringBuffer addPagingSql(Query query, StringBuffer anSqlString)
+ public StringBuffer addPagingSql(Query query, StringBuffer sql)
{
- // TODO: native paging support
- // not supported
throw new UnsupportedOperationException("OFFSET is not supported by
this platform" +
" implementation class (" + this.getClass().getName() +
"), please disable the native limit/offset flag in the" +
" connection metadata mapping file using attribute
'nativeLimitOffset'" +
" then OJB will use specific paging/limit result set iterator
to simulate it!");
+
+ // TODO: native paging support
+ /*
+ arminw:
+ Below are two paging implementation versions. It would be great if
someone
+ can check this against DB2.
+ To verify the implementation please run
org.apache.ojb.broker.PaginationTest
+ from OJB's test suite.
+ Please check methods #buildLimit(...) and buildOffset(...) too (maybe
need tweak).
+ */
+
+ /* Version A
+ int orderByIndex = sql.toString().toLowerCase().indexOf("order by");
+ int selectIndex = sql.toString().toLowerCase().indexOf("select");
+ boolean isOrderBy = orderByIndex > -1;
+
+ StringBuffer result = new StringBuffer().append("select * from (
select row_number() over(");
+ if(!query.isDistinct() && isOrderBy)
+ {
+ result.append(sql.toString().substring(orderByIndex));
+ }
+ result.append(" ) as rownum_,");
+ if(query.isDistinct())
+ {
+ result.append(" row_.* from ( ").append(sql.toString()).append(" )
as row_");
+ }
+ else
+ {
+ result.append(sql.toString().substring(selectIndex + 6));
+ }
+ result.append(" ) as foo_ where rownum_ >
").append(buildOffset(query)).append(" and rownum_ <=
").append(buildLimit(query));
+ return result;
+ */
+
+ /* Version B
+ StringBuffer result = new StringBuffer();
+ result.append("select bar_.* from ( select foo_.*, row_number() over()
as rownum_ from ( ")
+ .append(sql.toString())
+ .append(" ) as foo_ ) as bar_ where rownum_ > ")
+ .append(buildOffset(query))
+ .append(" and rownum_ <= ")
+ .append(buildLimit(query));
+ return result;
+ */
}
public int buildLimit(Query query)
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