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From Rick Hillegas <rick.hille...@oracle.com>
Subject Re: derbydump equivalent of mysqldump
Date Mon, 17 Dec 2012 13:49:19 GMT
On 12/14/12 7:02 PM, Aristedes Maniatis wrote:
> On 15/12/12 12:50am, Rick Hillegas wrote:
>> On 12/13/12 10:58 PM, Aristedes Maniatis wrote:
>>> I understand that such a thing does not exist, and I need to write 
>>> one for my own needs. Does anyone have any pointers on where to 
>>> start with this? What I want is output of SQL commands to create the 
>>> database, tables, indices, etc and also insert statements for all 
>>> the data. We need to migrate some Derby data to another database and 
>>> this appears the simplest approach.
>>>
>>>
>>> Would such a feature be a useful contribution toward the project, or 
>>> should we just work on this outside Apache?
>> Hi Ari,
>>
>> This would definitely be a useful contribution. Doing your work in 
>> the open in the community means that other contributors can warn you 
>> about edge-cases you might not otherwise consider--and we will all 
>> learn from your experience. Even if the committers don't incorporate 
>> your tool in the product, you can still attach it to a JIRA for use 
>> by other developers.
>
> Sorry, I wasn't clear enough in my email. As an Apache member, I have 
> no problem with the contribution of open source. I was more asking 
> whether such code would be useful to the project. And since I have 
> only a small problem to solve just now, I'm not sure whether this will 
> be a generic broadly useful piece of code or a solution just for what 
> I need.
>
>
>> If I understand correctly, you want to write a tool which copies one 
>> Derby database to another. As I see it, there are 2 big pieces to 
>> this project:
>>
>> 1) Generating the DDL to create all of the schema objects (tables, 
>> views, UDTs, etc.). The existing dblook program does much of this 
>> work already. However, more work needs to be done, particularly in 
>> the following areas:
>>
>> a) Generating DDL for GRANTs.
>>
>> b) Sorting the table DDL by foreign key dependencies.
>
> Because my initial goal is to import the result into mysql, this isn't 
> so important to me. And I can see how this sorting could be impossible 
> in some situations. There was a Jira request for the Derby project to 
> have a "disable all constraints" property like most other databases 
> have, but I seem to remember that it was closed as 'not wanted'. I 
> guess this is one reason no one has ever written a derbydump command 
> before.
>
>> c) Dumping database properties.
>>
>> d) Dumping NATIVE credentials.
>>
>> 2) Siphoning the data out of the source database into the target 
>> database. The most efficient tool we have for that task is the 
>> ForeignTableVTI attached to DERBY-4962. I recommend that you study 
>> that JIRA. (Note that I hope to be able to check a version of 
>> ForeignTableVTI into the product soon.) You will still need to 
>> generate INSERT statements in the correct order; hopefully you will 
>> be able to re-use the logic you write for (1b).
>
> Great, that's very helpful, thank you. We'll explore the code and see 
> where it takes us.
Hi Ari,

ForeignTableVTI is useful for bulk-importing a foreign schema into 
Derby. I'm afraid it won't help you bulk-export a Derby schema into a 
foreign database.

Regards,
-Rick
>
>
> Cheers
> Ari
>
>
>
>
>


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