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Connection-created LOBs should be usable #235

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
As verified in 
http://groups.google.com/group/h2-database/browse_thread/thread/086d3435f56a6fee
 the LOB locators returned from H2 when calling Connection.createBlob() et al 
are not usable.  

Please reconsider supporting this.  This is a natural idiom for handling LOBs 
in JDBC4l in fact as far as I can tell its the whole reason these methods were 
added in JDBC4.

Original issue reported on code.google.com by steven.e...@gmail.com on 8 Oct 2010 at 12:04

GoogleCodeExporter commented 9 years ago 
I want to use hibernate (3.6.0<=) + h2 (1.2.144<=) to store lob files. So I 
made some research to see if it would actually work.

1. I saw in org.h2.jdbc.JdbcBlob that JDBC 4 methods to modify Blob content are 
not supported. For example:
public OutputStream setBinaryStream(long pos) throws SQLException {
    throw unsupported("LOB update");
}
I want to note here that some of the new methods are supported (for example the 
"free" method both in JdbcBlob and JdbcClob).

2. I also saw that hibernate does some checks to see if the jdbc4 lob methods 
can be used or not (if not it falls back to its own lob handling). This is done 
in 
org.hibernate.engine.jdbc.JdbcSupportLoader.useContextualLobCreation(Connection)
 method. So hibernate uses the jdbc provided api if the jdbc 
DatabaseMetaData.getJDBCMajorVersion() returns at least 4 and if the free() 
method does not throw an exception on a test made Clob object.

3. Add to this I came upon issue #230, this is also listed in the h2 changelog:
"DatabaseMetaData.getJDBCMajorVersion now returns 4 (instead of 3) when the 
driver is compiled with Java 6 (the default)."

Based on 1 + 2 + 3 I concluded that I will fail. Because if everything works as 
seen in the source code and read in the changelog h2 will pass hibernates lob 
support test but will not actually support it.

But I made a maven quick test and it worked! Debugging showed that h2 returns 
jdbc support 3 so it seems that point #3 is actually not true. Running
javap -classpath h2-1.2.144.jar -verbose org.h2.jdbc.JdbcConnection | grep major
returned
major version: 49
So it seems the h2 jar in the central maven repo is compiled with java 1.5 and 
not 1.6.

The reason I wrote this long story in this issue because I want to highlight 
that if that #230 gets fixed for real, lob with hibernate will probably not 
work anymore.

Or maybe I just missed something and should be happy that things are working 
for now.

Original comment by kiralyat...@gmail.com on 2 Nov 2010 at 11:11

GoogleCodeExporter commented 9 years ago 
Thanks! It's definitely a feature that should be added soon.

Original comment by thomas.t...@gmail.com on 2 Nov 2010 at 7:36

GoogleCodeExporter commented 9 years ago 
Will be implemented in the next release.

Original comment by thomas.t...@gmail.com on 5 Nov 2010 at 9:16

GoogleCodeExporter commented 9 years ago 
Supported in version 1.3.146 (Beta). However, the default h2.jar file is 
currently compiled using Java 5, so Hibernate will not use the new feature 
using the default jar file.

Original comment by thomas.t...@gmail.com on 8 Nov 2010 at 9:55

GoogleCodeExporter commented 9 years ago

Original comment by thomas.t...@gmail.com on 14 Dec 2010 at 8:30

GoogleCodeExporter commented 9 years ago 
The status here shows "Started" but you had said it is in 1.3.146.  I see the 
latest release as 1.3.153.  So is this implemented?

On related note, you had mentioned that "the default h2.jar file is currently 
compiled using Java 5".  Have you either reconsidered this, or considered 
deploying a version built with Java 6 (JDBC 4 support) and uploading to 
maven-repo-of-choice as well?  You could leverage Maven's notion of a qualifier 
for the Java 6 build

Original comment by steven.e...@gmail.com on 23 Mar 2011 at 8:46

GoogleCodeExporter commented 9 years ago 
It is supported since version 1.3.146. However, the default h2.jar file is 
currently compiled using Java 5, so Hibernate will not use the new feature 
using the default jar file.

> Java 5 ... Have you either reconsidered this

Sure. Just I didn't switch to Java 6 yet. I guess this will be done for H2 
version 1.4 (maybe earlier).

> You could leverage Maven's notion of a qualifier for the Java 6 build

The H2 build doesn't use Maven, and there are no plans to use Maven. To 
understand why, please read the H2 build - you will see it wouldn't fit very 
well in what Maven provides, plus there would be many disadvantages when using 
Maven. Or did I misunderstand your request?

Original comment by thomas.t...@gmail.com on 27 Mar 2011 at 6:11

GoogleCodeExporter commented 9 years ago 
No, I did not mean building with Maven.  I meant in terms of making the 
artifacts available in the Maven repository.  Essentially you can upload 2 jars 
for the same release that are distinguished by what is called a classifier.  In 
your case you could have the default artifact (no classifier) for jdk5 and then 
a classified one for jdk6.

Again, you do not have build with Maven.

But it does assume that you are the one that does the uploading to Maven 
repository.  If you are not, then I would need to direct the request elsewhere.

Original comment by steven.e...@gmail.com on 27 Mar 2011 at 6:20

GoogleCodeExporter commented 9 years ago 
> I meant in terms of making the artifacts available in the Maven repository

Ah, OK, yes that's possible. I upload the the files, so I will have a look at 
that. Thanks a lot!

Original comment by thomas.t...@gmail.com on 27 Mar 2011 at 6:51

GoogleCodeExporter commented 9 years ago 
Hey Thomas, any word on this?  Especially as Java 5 is nearing EOL...

Original comment by steven.e...@gmail.com on 27 Aug 2012 at 6:03

GoogleCodeExporter commented 9 years ago 
Hi,

I think it does make sense to use Java 6 now by default. I can't promise this 
will be the case in the next release, but I will try.

Regards,
Thomas

Original comment by thomas.t...@gmail.com on 29 Aug 2012 at 7:54

GoogleCodeExporter commented 9 years ago 
Well more I am even thinking of the multiple artifact uploads I mentioned 
before.  I think that is the way to go as Java 6 (JDBC 4) and 7 (JDBC 4.1) have 
introduced minor JDBC changes, and that is currently the plan for Java 8 (JDBC 
4.2) as well.  Everyone having to recompile H2 on their own for these different 
JREs is not really fun.  Especially when you could do it once and upload 
artifacts for each...

Original comment by steven.e...@gmail.com on 29 Aug 2012 at 8:03

GoogleCodeExporter commented 9 years ago 
This should be fixed in version 1.3.169, as the jar file is now compiled for 
Java 6. By the way, it will probably take a while until the jar file is in the 
Maven Central repository.

Original comment by thomas.t...@gmail.com on 9 Sep 2012 at 12:21

GoogleCodeExporter commented 9 years ago

Original comment by thomas.t...@gmail.com on 9 Sep 2012 at 12:21