This looks like it might be a bug? As far as I can tell we're parsing the hint value and then using it at runtime.... but I can't find any tests where we actually exercise this functionality. Perhaps you could put together a small OpenJPA UT that recreates the problem[1]? Also, what version of OpenJPA are you using?
[parse] -- org.apache.openjpa.persistence.XMLPersistenceMetaDataParser <eclipse-javadoc:%E2%98%82=openjpa-persistence/src%5C/main%5C/java%3Corg.apache.openjpa.persistence%7BXMLPersistenceMetaDataParser.java%E2%98%83XMLPersistenceMetaDataParser> .startQueryHint(...) [runtime] -- org.apache.openjpa.persistence.EntityManagerImpl <eclipse-javadoc:%E2%98%82=openjpa-persistence/src%5C/main%5C/java%3Corg.apache.openjpa.persistence%7BEntityManagerImpl.java%E2%98%83EntityManagerImpl> .createNamedQuery(...) [1] http://openjpa.apache.org/testing.html On Mon, Jul 20, 2015 at 9:58 AM, Kariem Hussein <kariem.huss...@gmail.com> wrote: > Hi (again), > > I've asked the same question on StackOverflow [1] and was pointed to a > similar question [2] and actually found the well-hidden option to change > this behavior by setting the hint UseLiteralInSql to true [3]. > > It seems to work, when I set this on the javax.persistence.Query, but it > does not work, when I set the appropriate hint in orm.xml: > > <named-query name="person.v"> > <query> > select p > from Person p > where p.type = 'V' > </query> > <hint name="openjpa.hint.UseLiteralInSQL" value="true" /> > </named-query> > > Something wrong with this, or is there a limitation I am running into? > > Thank you very much, > Kariem > > > [1] How can I prevent OpenJPA from replacing “constant” parameters in my > queries? > http://stackoverflow.com/questions/31516813 > > [2] jpa namedquery with literals changed to prepared statement > http://stackoverflow.com/questions/28317482 > > [3] Javadoc org.apache.openjpa.kernel.QueryHints.HINT_USE_LITERAL_IN_SQL > > http://openjpa.apache.org/builds/2.4.0/apidocs/org/apache/openjpa/kernel/QueryHints.html#HINT_USE_LITERAL_IN_SQL > > On Thu, Jul 16, 2015 at 2:30 PM, Kariem Hussein <kariem.huss...@gmail.com> > wrote: > > > Hi there, > > > > I am in the process of migrating a big (old) code base from JPA 1 with > > Hibernate 3.3 to JPA 2 with OpenJPA. I've had a problem with a query that > > used to work in the old version and now does not and I wanted to know > > whether my reasoning is correct. > > > > I have already reduced the problem description to the minimal and I hope > I > > did not lose relevant pieces of information on the way. > > > > Given this table in Oracle > > > > create table PERSON ( > > id char(10) not null, > > type char(3) not null, > > primary key (id) > > ) > > > > There are a lot of rows with in total three different types "WTW", "WAI", > > "V" (to be honest, I don't know what they stand for). However, we have an > > entity to work with this table: > > > > @Entity > > public class Person { > > String id; > > String type; > > } > > > > The following query is used in the application from an orm.xml file: > > > > <named-query name="person.v"> > > <query> > > select p > > from Person p > > where p.type = 'V' > > </query> > > </named-query> > > > > As the `type` field is `char(3)`, Oracle will store `V ` ('V' followed > > by two spaces) for the string "V". > > > > In Hibernate, I did not have a problem with this query, but with OpenJPA, > > there is some magic performance improvement on this query that reduces > the > > number of queries by normalizing permutations -- at least that is what I > > think why my query was translated this way -- which results in the > > following SQL being sent to the DB > > > > select p.id, p.type > > from PERSON p > > where p.type = ? > > > > The "constant" parameter for `type` in my query was replaced with an SQL > > parameter and the OpenJPA log shows that "V" is passed as value. I > believe > > that because of this replacement I do not get any results anymore. > > > > It works if I do one of the following > > > > - (a) Adapt the JPQL query to `where p.type = 'V '`, effectively knowing > > about the underlying `char(3)` field. > > - (b) Use a native query. OpenJPA will then not try to "improve" my query > > in a way that changes its semantics. > > > > Is there something I can do to improve this behavior in JPA? Is there any > > benefit in replacing a "constant" parameter in a named query that is only > > used in this way (there are no permutations). > > > > Shouldn't the parameter be converted correctly (including padding) into > > the DB type? Is this a bug, or do I have to specify some kind of hint? > > > > > > Thank you for your comments, > > Kariem > > > > > -- *Rick Curtis*
