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From "Patrick Linskey" <plins...@bea.com>
Subject RE: [jira] Commented: (OPENJPA-221) DerbyDictionary doesn't describe a working mapping for char fields.
Date Wed, 18 Apr 2007 22:37:22 GMT
> Does that mean you store Strings as arrays of integers by 
> default for the same reason?

No.

> Why is this different?

Because we've regularly run into problems with chars, and have found
that mapping them as ints by default gets around the problems.

> There aren't any non-incubator openjpa releases yet, so I 
> don't see the problem. 

Any other opinions?

> I'd also expect that for preexisting 
> tables either an INTEGER or CHAR column would work.

They do, as long as you configure things correctly.

> > openjpa.Log: SQL=TRACE
> 
> Where would I put this so I could see what the unit tests were doing?

What are "the unit tests"? Your tests, or the tests in the OpenJPA
project?

For your tests, add a <property name="openjpa.Log" value="SQL=TRACE"/>
to your persistence unit. See
http://incubator.apache.org/openjpa/docs/latest/manual/manual.html#ref_g
uide_logging.

> (1) is a lot more important, but changing the answer to (2) 
> is easier and solves my immediate problem.

I don't think that 1 is important, since you can trivially set
storeCharsAsNumbers to true. Ditto for 2.

-Patrick

-- 
Patrick Linskey
BEA Systems, Inc.
_______________________________________________________________________
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> -----Original Message-----
> From: David Jencks [mailto:david_jencks@yahoo.com] 
> Sent: Wednesday, April 18, 2007 3:20 PM
> To: open-jpa-dev@incubator.apache.org
> Subject: Re: [jira] Commented: (OPENJPA-221) DerbyDictionary 
> doesn't describe a working mapping for char fields.
> 
> 
> On Apr 18, 2007, at 11:12 AM, Patrick Linskey wrote:
> 
> > Hi,
> >
> >
> >> IIUC derby is a pure java db optimized for use with java 
> and storing 
> >> java primitive types basically using java serialization.  
> Why would 
> >> openjpa want to store a char in derby as an integer?
> >
> > "Because we've always done it that way." Is there a reason why we 
> > should not be storing chars as numbers? Historically, we've seen 
> > problems with comparisons and localization issues when 
> storing chars 
> > as chars, which is why we store them as ints by default.
> 
> Does that mean you store Strings as arrays of integers by 
> default for the same reason?  Why is this different?
> 
> > Based on the fact that you said
> > that the unit tests fail with Derby with that configuration 
> change, it 
> > sounds like there are some sorts of issues with char mappings in 
> > Derby.
> 
> The unit tests fail with only the storeCharsAsIntegers=false 
> because the sql for creating the table is invalid.  They 
> succeed with the additional patch to create a CHAR(1) column 
> instead of CHAR(255) for a char field.  I'm happy to discuss 
> if creating a  CHAR(255) column to store a char field is 
> reasonable :-)
> >
> > Additionally, since we've always done it that way, changing 
> would mean 
> > backwards-compatibility problems.
> 
> There aren't any non-incubator openjpa releases yet, so I 
> don't see the problem.  I'd also expect that for preexisting 
> tables either an INTEGER or CHAR column would work.
> 
> >
> >> Why are the current settings correct, despite not working with the 
> >> obvious char <> CHAR mapping?
> >
> > How do you define "not working"? It's my expectation that if the 
> > application behaves as expected, then things are working. It sounds 
> > like what you're saying is "the default is not what was 
> expected", not 
> > that "things don't work".
> 
> I expect that if I have a char field in an object and a 
> preexisting table with a CHAR column openjpa will figure out 
> some way to get a char from the field to the column and back 
> again without any additional configuration, for all 
> databases.  Admittedly my proposed fix only does this for 
> derby, and by changing the default mapping for chars for derby.
> 
> I additionally expect that if openjpa creates a schema for me 
> for a database with default utf support it will map a char 
> field to a CHAR column.  I wouldn't necessarily expect this 
> for a database that by default doesn't have utf columns.
> 
> >
> >> I haven't found the magic setting so I can see what table is being 
> >> created for the unit tests
> >
> > openjpa.Log: SQL=TRACE
> 
> Where would I put this so I could see what the unit tests were doing?
> 
> I think there are 2 issues here:
> 
> 1. should openjpa be able to use a preexisting CHAR column 
> for storing a char, no matter what the storeCharsAsInteger setting is?
> 2. should the settings for derby be storeCharsAsInteger = 
> false or true?
> 
> (1) is a lot more important, but changing the answer to (2) 
> is easier and solves my immediate problem.
> 
> thanks
> david jencks
> 
> >
> > -Patrick
> >
> > --
> > Patrick Linskey
> > BEA Systems, Inc.
> > 
> ______________________________________________________________________
> > _
> > Notice:  This email message, together with any attachments, may 
> > contain
> > information  of  BEA Systems,  Inc.,  its subsidiaries  and   
> > affiliated
> > entities,  that may be confidential,  proprietary,  copyrighted   
> > and/or
> > legally privileged, and is intended solely for the use of the 
> > individual or entity named in this message. If you are not the 
> > intended recipient, and have received this message in error, please 
> > immediately return this by email and then delete it.
> >
> >> -----Original Message-----
> >> From: David Jencks [mailto:david_jencks@yahoo.com]
> >> Sent: Wednesday, April 18, 2007 10:53 AM
> >> To: open-jpa-dev@incubator.apache.org
> >> Subject: Re: [jira] Commented: (OPENJPA-221) 
> DerbyDictionary doesn't 
> >> describe a working mapping for char fields.
> >>
> >> I'm not understanding something, maybe someone could explain, and 
> >> obviously the comments I suggested in DBDictionary are completely 
> >> wrong, although I sure don't see why.
> >>
> >> IIUC derby is a pure java db optimized for use with java 
> and storing 
> >> java primitive types basically using java serialization.  
> Why would 
> >> openjpa want to store a char in derby as an integer?  Why are the 
> >> current settings correct, despite not working with the 
> obvious char 
> >> <> CHAR mapping?  I haven't found the magic setting so I 
> can see what 
> >> table is being created for the unit tests, but I'm pretty sure it 
> >> isn't creating a CHAR column for the char field in the allTypes 
> >> object.
> >>
> >> I assumed the problems I ran into were a result of no one having 
> >> tested this code path, but you appear to be saying that 
> the current 
> >> code is more correct than my proposal.  I'd really like to 
> know why.
> >>
> >> On Apr 18, 2007, at 10:18 AM, Patrick Linskey (JIRA) wrote:
> >>
> >>>
> >>>     [ https://issues.apache.org/jira/browse/OPENJPA-221?
> >>> page=com.atlassian.jira.plugin.system.issuetabpanels:comment-
> >>> tabpanel#action_12489820 ]
> >>>
> >>> Patrick Linskey commented on OPENJPA-221:
> >>> -----------------------------------------
> >>>
> >>> It's not surprising that the OpenJPA tests
> >> storeCharsAsNumbers to be
> >>> true.
> >>
> >> maybe to you :-)  I still find it extremely surprising, and can't 
> >> imagine any reason why you'd want to do this.
> >>>
> >>> I was referring to your test environment. Rather than 
> changing the 
> >>> default behavior of the DerbyDictionary in code, it seems more 
> >>> appropriate to use the built-in configuration option to
> >> toggle it for
> >>> your application.
> >>>
> >>> It sounds like you're reluctant to do this since you don't
> >> have easy
> >>> access to modify the persistence.xml files. Happily, if 
> you drop a 
> >>> file conforming to the persistence.xml schema into META-INF/ 
> >>> openjpa.xml, OpenJPA will load the settings in the
> >> properties in the
> >>> first PU in that file as defaults for all PUs.
> >>>
> >>> What happens if you put the DBDictionary stanza that I mentioned 
> >>> earlier into a META-INF/openjpa.xml file?
> >>
> >> Won't this change the behavior for all databases, not just 
> the derby 
> >> dictionary?  I'd prefer to
> >>
> >> (a) understand why these settings as are they are
> >> (b) make all the db-specific dictionaries work unmodified with all 
> >> reasonable mappings.
> >>
> >> thanks
> >> david jencks
> >>
> >>
> >>>
> >>>> DerbyDictionary doesn't describe a working mapping for 
> char fields.
> >>>> 
> -------------------------------------------------------------------
> >>>>
> >>>>                 Key: OPENJPA-221
> >>>>                 URL: https://issues.apache.org/jira/browse/
> >>>> OPENJPA-221
> >>>>             Project: OpenJPA
> >>>>          Issue Type: Bug
> >>>>          Components: sql
> >>>>    Affects Versions: 0.9.7
> >>>>            Reporter: David Jencks
> >>>>         Attachments: OPENJPA-221.patch
> >>>>
> >>>>
> >>>> If a class has a char field mapped to CHAR or CHAR(1) in a derby 
> >>>> database, the derby dictionary sets up a mapping to an
> >> integer column
> >>>> which doesn't work.  openjpa tries to store e.g. the
> >> string "97" for
> >>>> the char 'a' which results in a truncation error.
> >>>
> >>> --
> >>> This message is automatically generated by JIRA.
> >>> -
> >>> You can reply to this email to add a comment to the issue online.
> >>>
> >>
> >>
> >
> > Notice:  This email message, together with any attachments, may  
> > contain information  of  BEA Systems,  Inc.,  its subsidiaries   
> > and  affiliated entities,  that may be confidential,  
> proprietary,   
> > copyrighted  and/or legally privileged, and is intended 
> solely for the 
> > use of the individual or entity named in this message. If 
> you are not 
> > the intended recipient, and have received this message in error, 
> > please immediately return this by email and then delete it.
> 
> 

Notice:  This email message, together with any attachments, may contain information  of  BEA
Systems,  Inc.,  its subsidiaries  and  affiliated entities,  that may be confidential,  proprietary,
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or entity named in this message. If you are not the intended recipient, and have received
this message in error, please immediately return this by email and then delete it.

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