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From "Rakesh Jain (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (OPENJPA-2352) Retrieving column index for non existing field throws SQLException (ignored) causing slowness in application server
Date Fri, 29 Mar 2013 17:55:15 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-2352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617558#comment-13617558
] 

Rakesh Jain commented on OPENJPA-2352:
--------------------------------------

Here is my scenario, I am putting in quite simplified form.

I have a bean called TestBean which contains 5 fields. Then I have a named query which has
implicit mapping of three fields of this bean. The other two fields are not mapped in any
way for this named query.

@NamedNativeQuery
(
	name="testNamed", 
	query="select s.SERVER_ID as serverId, s.SERVER_NAME as serverName, s.PORT_NUMBER as portNumber
from server_table s ",
	resultClass=TestBean.class
)

@Entity
public class TestBean
{ 
	@Id
	private int serverId;

	private String serverName;
	
	private int portNumber;
	
	private String serverUrl;
	private String serverLocation;
        
       //geters/setters//
}

(In actual I will have complex query joining multiple tables).
Now, when I execute this named query using the following:

                        TypedQuery<TestBean> q = em.createNamedQuery( "testNamed", TestBean.class);

			List<TestBean> res = q.getResultList();

I get the results back fine. However, if you look at the logs (I have jdbc.JDBC.level set
to max debug), you see the following:

2013-03-29 10:49:49.266-07:00        [jcc][10150][10300][4.15.82] Invalid parameter: Unknown
column name SERVERLOCATION. ERRORCODE=-4460, SQLSTATE=null

2013-03-29 10:49:49.266-07:00        [jcc][10150][10300][4.15.82] Invalid parameter: Unknown
column name SERVERURL. ERRORCODE=-4460, SQLSTATE=null

Which is coming from that exception block in the ResultSetResult class, and it is actually
happening for every single row, so shows up as many times as the number of records returned.

I would prefer to not go in that exception block at all, as otherwise it slows down the getResultList()
method is app servers, even though it works perfectly fine in Tomcat or standalone Java.

Hope this helps.

                
> Retrieving column index for non existing field throws SQLException (ignored) causing
slowness in application server
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: OPENJPA-2352
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-2352
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: jdbc
>    Affects Versions: 2.1.1
>         Environment: All OS, I have tried with DB2 but problem may exist for all databases.
WebSphere.
>            Reporter: Rakesh Jain
>              Labels: ResultSetResult,, exception, ignored, jdbc,
>
> When we have defined NamedNativeQuery and the query contains let's say 4 columns. Now
if we have a resultClass associated to that query which is simply a POJO having let's say
five fields, four of which are mapped to the 4 columns of the NamedNativeQuery, but the fifth
one is not (after all it is POJO), the JPA tries to retrieve column index for that fifth field,
and that throws SQL exception. The JPA code though ignores this exception, returning zero
for column index. However, because an exception is throws, the application server in which
this code is executing captures it and logs it in its corresponding logs. This causes the
population of the result bean slow, and very slow if there are 4-5 or more fields unmapped.
> Here's the code fragment from org.apache.openjpa.jdbc.sql.ResultSetResult.java where
this is happening.
> /**
> * Return the 1-based result set index for the given column or id, or a
> * non-positive number if the column is not contained in this result.
> */
> protected int findObject(Object obj, Joins joins)
> throws SQLException {
> try {
> String s1 = obj.toString();
> DBIdentifier sName = DBIdentifier.newColumn(obj.toString());
> return getResultSet().findColumn(_dict.convertSchemaCase(sName));
> } catch (SQLException se) {
> return 0;
> }
> }
> Moreover, this same method is called multiple times for each field, multiplying the problem.
> I would think a better approach would be to use ResultSetMetaData to retrieve all the
column names and indexes, cache them and simply return from that cache in the findObject method.
> Is there any reason to keep it like this and not change to use metadata?

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