Re: [hibernate-dev] HHH-6726 LONG and LONG RAW column types in Oracle
by Łukasz Antoniak
Currently Oracle supports database versions from 10.1 to 11.2 [1]. LONG
and LONG RAW data types are deprecated since version 8 and 8i (released
before September 2000) [2]. Oracle keeps those column types only for
backward compatibility [3].
I tried the following scenario (Oracle 10gR2):
1. Create schema with "hibernate.hbm2ddl.auto" set to "create". The LONG
column is created.
2. Insert some data.
3. Modify Oracle dialect as Gail suggested. Avoid setting
"hibernate.hbm2ddl.auto".
4. Insert some data.
To my surprise the test actually passed :). However, I think that we
cannot guaranty the proper behavior in every situation.
As for performance, ImageType is extracted by calling
ResultSet.getBytes() method, which fetches all data in one call [4]. I
don't suppose a major performance difference when data is streamed in
another call. oracle.jdbc.driver.LongRawAccessor.getBytes also fetches
data by reading the stream.
The bug reading LONG column affects JDBC drivers since version 10.2.0.4.
I think that we have to choose between:
- changing Oracle10gDialect. Make a not about it in migration guide to
4.0 and update "5.2.2. Basic value types" chapter in Hibernate
documentation.
- introducing Oracle11gDialect. It can sound weird to access Oracle 10g
database with Oracle 11g dialect.
- disabling execution of Hibernate tests that fail because of this issue
with @SkipForDialect (and maybe develop another version of them with
CLOBs and BLOBs, @RequiresDialect). Hibernate is written correctly
according to "Default Mappings Between SQL Types and Java Types"
(referenced earlier by Gail) and this is more Oracle's JDBC
implementation issue. This option came to my mind, but it's weird :P.
I would vote for the first option.
Regards,
Lukasz Antoniak
[1]
http://www.oracle.com/us/support/library/lifetime-support-technology-0691...
(page 4)
[2]
http://download.oracle.com/docs/cd/A91202_01/901_doc/server.901/a90120/ch...
[3]
http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/datatype.htm
[4] "Getting a LONG RAW Data Column with getBytes"
http://download.oracle.com/docs/cd/B19306_01/java.102/b14355/jstreams.htm
Strong Liu pisze:
> I think oracle 11g is the only one supported DB version by oracle, can we just introduce a new oracle dialect with suggested changes, and deprecate all other existed oracle dialects? this won't affects users app
>
> -----------
> Strong Liu <stliu(a)hibernate.org>
> http://hibernate.org
> http://github.com/stliu
>
> On Oct 15, 2011, at 11:14 AM, Scott Marlow wrote:
>
>> How does this impact existing applications? Would they have to convert
>> LONGs to CLOBs (and LONGRAWs to BLOBs) to keep the application working?
>>
>> As far as the advantage of CLOB over TEXT, if you read every character,
>> which one is really faster? I would expect TEXT to be a little faster,
>> since the server side will send the characters before they are asked
>> for. By faster, I mean from the application performance point of view. :)
>>
>> Could this be changed in a custom Oracle dialect? So new
>> applications/databases could perhaps use that and existing applications
>> might use LONGs a bit longer via the existing Oracle dialect.
>>
>> On 10/14/2011 09:22 PM, Gail Badner wrote:
>>> In [1], I am seeing the following type mappings:
>>>
>>> Column type: LONG -> java.sql.Types.LONGVARCHAR -> java.lang.String
>>> Column type: LONGRAW -> java.sql.Types.LONGVARBINARY -> byte[]
>>>
>>> org.hibernate.type.TextType is consistent with the mapping for LONG.
>>>
>>> org.hibernate.type.ImageType is consistent with the mapping for LONGRAW.
>>>
>>> From this standpoint, the current settings are appropriate.
>>>
>>> I understand there are restrictions when LONG and LONGRAW are used and I see from your other message that there is Oracle documentation for migrating to CLOB and BLOB.
>>>
>>> I agree that changing column type registration as follows (for Oracle only) should fix this:
>>> registerColumnType( Types.VARBINARY, 2000, "raw($l)" );
>>> registerColumnType( Types.VARBINARY, "blob" );
>>>
>>> registerColumnType( Types.LONGVARCHAR, "clob" );
>>> registerColumnType( Types.LONGVARBINARY, "blob" );
>>>
>>> registerColumnType( Types.VARCHAR, 4000, "varchar2($l char)" );
>>> registerColumnType( Types.VARCHAR, "clob" );
>>>
>>> Steve, what do you think? Is it too late to make this change for 4.0.0?
>>>
>>> [1] Table 11-1 of Oracle® Database JDBC Developer's Guide and Reference, 11g Release 1 (11.1) (http://download.oracle.com/docs/cd/B28359_01/java.111/b31224/datacc.htm#g...)
>>> [2] Hibernate Core Migration Guide for 3.5 (http://community.jboss.org/wiki/HibernateCoreMigrationGuide35)
>>> [3] Table 2-10 of Oracle® Database SQL Language Reference
>>> 11g Release 1 (11.1) (http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/sql_elemen...)
>>>
>>> ----- Original Message -----
>>>> From: "Łukasz Antoniak"<lukasz.antoniak(a)gmail.com>
>>>> To: hibernate-dev(a)lists.jboss.org
>>>> Sent: Thursday, October 13, 2011 12:50:13 PM
>>>> Subject: [hibernate-dev] HHH-6726 LONG and LONG RAW column types in Oracle
>>>>
>>>> Welcome Community!
>>>>
>>>> I have just subscribed to the list and wanted to discuss HHH-6726
>>>> JIRA
>>>> issue.
>>>>
>>>> Gail Badner wrote
>>>> (http://lists.jboss.org/pipermail/hibernate-dev/2011-October/007208.html):
>>>> HHH-6726 (Oracle : map TextType to clob and ImageType to blob)
>>>> https://hibernate.onjira.com/browse/HHH-6726
>>>> There have been a number of issues opened since the change was made
>>>> to
>>>> map TextType (LONGVARCHAR) 'long' and ImageType (LONGVARBINARY) to
>>>> 'long
>>>> raw'. This change was already documented in the migration notes.
>>>> Should
>>>> the mapping for Oracle (only) be changed back to clob and blob?
>>>>
>>>> HHH-6726 is caused by an issue in Oracle JDBC driver (version
>>>> 10.2.0.4
>>>> and later). This bug appears when LONG or LONG RAW columns are
>>>> accessed
>>>> not as first or last while processing SQL statement.
>>>>
>>>> I have discussed the topic of mapping TextType to CLOB and ImageType
>>>> to
>>>> BLOB (only in Oracle dialect) with Strong Liu. Reasons for doing so:
>>>> - Oracle allows only one LONG / LONG RAW column per table. This might
>>>> be
>>>> the most important from Hibernate's perspective.
>>>> - LONG / LONG RAW - up to 2 GB, BLOB / CLOB - up to 4 GB.
>>>> - In PL/SQL using LOBs is more efficient (random access to data).
>>>> LONG
>>>> only sequential.
>>>> - LONG and LONG RAW are deprecated.
>>>>
>>>> What is your opinion?
>>>>
>>>> Regards,
>>>> Lukasz Antoniak
>>>> _______________________________________________
>>>> hibernate-dev mailing list
>>>> hibernate-dev(a)lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>>
>>> _______________________________________________
>>> hibernate-dev mailing list
>>> hibernate-dev(a)lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>> _______________________________________________
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>
8 years, 9 months
Changelog file in Hibernate ORM
by Sanne Grinovero
The file changelog.txt in the root ot the Hibernate ORM project seems outdated.
Is it not maintained anymore? I found it handy.
Sanne
9 years, 5 months
New CI machine preview
by Sanne Grinovero
You're all welcome to play with http://54.225.162.168/
however please keep these in mind:
- it's not the final machine: don't put too much effort in creating
nice build scripts as we'll reset it to clean state soon. We *might*
be able to store jobs defined so far, but we might choose not to.
- domain name should be coming: ci.hibernate.org ..not sure when, got
no replies so far from.
- authentication: just click on login, it will use OAuth2 to request
your identity via your GitHub account. Permissions to create new jobs,
edit existing jobs, run a build manually depend on your github account
be part of the Hibernate organization (or not, in which case you have
read only status)
At this stage I'd like to get a feeling if the hardware is powerful
enough, and also we need to select which other plugins we want to use,
I'm looking especially to:
- static analysis reports
- pull requests integration
both are relatively undefined, we can of course start simple and
improve later.. just checking this fits basic needs now.
Sanne
11 years, 7 months
unexpected warn message
by Strong Liu
seeing this when running test on master
"22:34:30,288 WARN SessionFactoryImpl:1554 - HHH000008: JTASessionContext being used with JDBCTransactionFactory; auto-flush will not operate correctly with getCurrentSession()
"
in the method of org.hibernate.internal.SessionFactoryImpl#buildCurrentSessionContext, even there is no Environment.CURRENT_SESSION_CONTEXT_CLASS property set, it use the following logic to guess
if ( canAccessTransactionManager() ) {
impl = "jta";
}
and org.hibernate.engine.transaction.jta.platform.internal.StandardJtaPlatformResolver#resolveJtaPlatform, if there is any JTA Impl on the classpath, the method usually returns true canAccessTransactionManager()
-------------------------
Best Regards,
Strong Liu <stliu at hibernate.org>
http://about.me/stliu/bio
11 years, 8 months
JAXB question
by Strong Liu
Hi JAXB expert
I'm trying to do the merge master onto metamodel again, but run into some JAXB problems and I'd like to ask for suggestions.
as you know, we compile the orm.xsd to jaxb generated class, and there is a package-info.java generated for schema validation, this class looks like
{code}
@javax.xml.bind.annotation.XmlSchema(namespace = "http://java.sun.com/xml/ns/persistence/orm", elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)
package org.hibernate.jaxb.spi.orm;
{code}
but due to the namespace of orm.xsd changed since JPA 2.1 ( from "http://java.sun.com/xml/ns/persistence/orm" to "http://xmlns.jcp.org/xml/ns/persistence/orm", btw, any idea why? )
for now, I created a org.hibernate.jaxb.internal.LegacyJPAEventReader, which will modify the legacy namespace to the new one ( also changing the version to 2.1 )
but with this applied, the jaxb schema validation is always fail no matter which schema is used.
so, I came up with another idea, if the original orm.xml is 2.1 then go ahead with jaxb validation, or, we disable jaxb schema validation and apply stax schema validation before org.hibernate.jaxb.internal.LegacyJPAEventReader came into play
( see org.hibernate.jaxb.internal.JaxbMappingProcessor#unmarshal ) sadly, it doesn't work :( validation still fail, can be reproduced by org.hibernate.metamodel.internal.source.annotations.xml.OrmXmlParserTests#testInvalidOrmXmlThrowsException
so, any suggestions?
-------------------------
Best Regards,
Strong Liu <stliu at hibernate.org>
http://about.me/stliu/bio
11 years, 8 months
Jira notifications
by Steve Ebersole
I am looking into the problem of hibernate-issues no longer getting Jira
notifications. One possible reason is the use of the custom
"Participants" field in our notification scheme. I am wondering if we
ought to remove that rule from the notification scheme. Atlassian have
added an "autowatch" field that kind of does the same thing. Basically
each user can enable/disable autowatch for themselves, which controls
whether they are automatically added as a watcher of any issues they
comment on. The notification scheme would then notify them as a watcher.
One downside to the current notification scheme is that participants can
never opt-out of notifications. So this might be a worthwhile change
anyway.
Dunno if that solves the problem with notifications to hibernate-issues
or not. But wanted to see what everyone else felt.
11 years, 8 months
