Skip to main content
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [eclipselink-users] Postgresql and UUID eclipselink 2.4.0 
On 08/10/2012 04:57 AM, Edward Mann wrote:

I am not sure what performance penalties if any this will introduce, but
this is how i got the uuid to work. I wanted to send this out so anyone
else having this issue can try this, and also get feedback on if this is
not a good thing to do.

I changed all the UUID to String and made the following two changes to
the persistent.xml file

for postgresql i am able to use ?stringtype=unspecified in the url for
the database connection.
Also i had to add
<property name="eclipselink.jdbc.bind-parameters" value="false" />
to the properties section. With both of those things are working as
expected. Granted all my tables are small so i might be in for a
surprise.

Thanks for your input everyone.


Hi Edward,
glad to hear you got it working. But when you don't let EclipseLink bind the parameters I think it may affect performance quite a lot, see here: 

http://eclipse.org/eclipselink/documentation/2.4/jpa/extensions/q_bindparameters.htm
So, I think you're better off with a converter. I've done this for the inet extension of PostgreSQL for different mappings, e.g. java.net.InetAddress: 

https://github.com/ancoron/pg-inet-maven/blob/master/org.ancoron.postgresql.jpa/src/main/java/org/ancoron/postgresql/jpa/eclipselink/InetAddressConverter.java
However, in case of UUID the PostgreSQL driver already is able to map java.lang.UUID to the internal uuid type for JDBC-3g and JDBC-4 connections: 

class AbstractJdbc3gStatement:

import java.sql.*;
import java.util.UUID;

import org.postgresql.core.Oid;
...
public void setObject(int parameterIndex, Object x) throws SQLException
{
    if (x instanceof UUID && connection.haveMinimumServerVersion("8.3"))
    {
        setString(parameterIndex, x.toString(), Oid.UUID);
    } else {
        super.setObject(parameterIndex, x);
    }
}
So your converter may just pass the java.lang.UUID object in and out - no conversion required at all. 

Cheers,

	Ancoron



On Tue, 2012-08-07 at 09:16 +0200, Ancoron Luciferis wrote:

Hi Edward,

I think you need to either:

1.) provide a custom converter (UUID (java) <-> UUID (PostgreSQL))

2.) provide an custom type mapping


...for 1.) there are enough information out there on the EclipseLink
wiki, for 2.) there is almost no information how to code that, as I
still have the same problem with other types.

Cheers,

	Ancoron


On 08/06/2012 07:11 PM, Edward Mann wrote:

I have been trying to figure out how to get the native uuid type in
          postgresql and eclipselink to work together. I have a simple
table for
          testing:

          CREATE TABLE elink
          (
            el_id uuid NOT NULL DEFAULT uuid_generate_v4(), -- elink id
            el_name character varying(255), -- elink name
            CONSTRAINT el_pkey PRIMARY KEY (el_id )
            DEFERRABLE INITIALLY IMMEDIATE
          )
          WITH (
            OIDS=FALSE
          );
          ALTER TABLE elink
          OWNER TO emann;
          COMMENT ON COLUMN elink.el_id IS 'elink id';
          COMMENT ON COLUMN elink.el_name IS 'elink name';


          And the annotation on the field for id is:

          @Id
                  @Column(name="el_id")
                  @UuidGenerator(name="uuid")
                  @GeneratedValue(generator="uuid")
                  private UUID elId;

          I have also tried the custom UUIDSequence mentioned on the
website,
          however that did not work either. I get the following error
(this is the
          UUIDSequence native to 2.4.0):

          Exception [EclipseLink-3002] (Eclipse Persistence Services -
          2.4.0.v20120608-r11652):
          org.eclipse.persistence.exceptions.ConversionException
          Exception Description: The object
          [66FB2FFB-2735-4A8C-AFDE-19246C78CC16], of class [class
          java.lang.String], from mapping

[org.eclipse.persistence.mappings.DirectToFieldMapping[elId-->ELINK.el_id]] with descriptor [RelationalDescriptor(model.Elink --> [DatabaseTable(ELINK)])], could not be converted to [class [B].


          So i am really curious about what is the proper way to get this
to work
          using uuid type in postgresql.
          Any help is welcome, thanks in advance.

_______________________________________________
eclipselink-users mailing list
eclipselink-users@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/eclipselink-users

Back to the top