Re: Migration between two different types of NoSQL Databases

[Andy Wenk]

Hi Piraengu,

On 12 July 2012 08:37, piraengu <pira...@gmail.com> wrote:
> Good Day everybody
>
> I'am a Computer Science Student in Switerland in the 3rd year and yesterday,
> I had a presentation about NoSQL, there I showed to the audience the
> different types in NoSQL.
>
> After the Presentation the team leader asked me how it is, to migrato the
> db's under various types.
> So i began to search something and all i found is this Community, and now i
> will asking you.
>
> All what i found is from RDBMS to NoSQL Systems, and if i'm right, there
> isn't a standard way to migrate between different types?
>
> Can I migrate from a, key-value store db, like dynamo, to a, document store
> db, like mongoDB?

as far as I know, there are no migration tools. I guess the approach
could be hard because the data are stored in various different styles.
E.g CouchDB is storing the data in JSON and MongDB has it's own format
callen BSON. So dumping like you could do from a MySQL to a PostgreSQL
Database is not possible. Furthermore it's not possible to dump to a
binary file like in PostgreSQL's pg_dump.

What you can do for sure is writing a script where you request the
data form one key-value store and pump the data into the other
key-value store. But remember, that there is no standard between the
databases at all. Every NoSQL database has it's own implementation for
receiving data, viewing data and so on. I guess it will be an
individual task for each migration from DB1 to DB2. On the other hand,
the data structures will be very simple as this is the fact for
key-value stores.

> Are there anywhere some tools that helps me or should i better write some
> scripts by my self?
>
> What should I observe if I want do that?
>
> I am not going to do that, it's just a question to educate me.
>
> Thanks for the Answers and the Information.
> Best Regards
> Piraengu

Cheers

Andy

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--
Andy Wenk
Hamburg - Germany
RockIt!

"CouchDB - Das Praxisbuch für Entwickler und Administratoren"
http://www.galileocomputing.de/2462
http://www.couchdb-buch.de

+++ english version is coming +++
http://www.couchdb-book.com

"PostgreSQL 8.4: Das Praxisbuch"
http://www.galileocomputing.de/2008
http://www.pg-praxisbuch.de

[piraengu]

Hi Andy

Thanks for the Information, this was really helpfull

Best Regards
Cyrill

Am Donnerstag, 12. Juli 2012 08:37:12 UTC+2 schrieb piraengu:

Good Day everybody

I'am a Computer Science Student in Switerland in the 3rd year and yesterday, I had a presentation about NoSQL, there I showed to the audience the different types in NoSQL.

After the Presentation the team leader asked me how it is, to migrato the db's under various types.
So i began to search something and all i found is this Community, and now i will asking you.

All what i found is from RDBMS to NoSQL Systems, and if i'm right, there isn't a standard way to migrate between different types?

Can I migrate from a, key-value store db, like dynamo, to a, document store db, like mongoDB?

[William la Forge]

I basically just want to elaborate a bit on what was said.

You need to look beyond a given database and learn about how the application(s) use the data, and understand which uses need to be fast, and which uses are infrequent and perhaps not even required. Then you need to see how the target database can be used to best support these uses.

This is a creative process, and will vary from application to application even with the same pair of databases. It is also likely that the application will need to be changed as well.

The main thing to be understood here is that the conversion is going to have some of the same failure modes as the classical version 2 of an application. Too often an application which has not been rewritten before contains many incidental features which are only present because they were easy to implement in the original version. These incidental features then place major constraints on the design of the rewrite, adding a lot of complexity and dramatically increase the likelihood of failure.

Bill la Forge

CTO, JActor Consulting

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[Andy Wenk]

Hey Cyrill,

you're welcome ;-). Did you find a way to get the job done?

Cheers

Andy

P.S.: The mentions from William la Forge are a really good read and
include some good advices you should follow ;-)

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