moving tables between databases

Question

For a bit fall cleaning, I am moving 25 tables between MySQL databases (different pieces of hardware). This is not the WHOLE database, just 25 tables out of a few hundred... These tables don't really belong in there, I won't go into why for NDA reasons.

Now, this is going to break a lot of code and sql queries.

What is the best way to go about doing this?

1. Move them all over at once.

2. Move them over 1 by 1

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Moving them over all at once, is kind of nice. Might be some outages and broken code that I missed, but moving them as a block is much faster, less time spent in pushing code out.

Moving them over one by one is kind of nice, less chance of big stuff breaking, but a LOT more time will be spent micromanaging the work, redundant work, and deploying.

Is it possible for me to mirror the tables between two databases for a while? A federated table perhaps?

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Misc info: There are 25 tables are all related by content to each other.

I cannot shutdown the databases for hours at a time, about 5 minutes of downtime would be acceptable.

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What is the best way to go about moving all of this data and keeping the code, sql, and me in great shape?

Could I federate the tables as a way of replicating the tables to a new database?

-daniel

Answer 1

It seems like moving them over one at a time would be the way to go. That way you have a bunch of easy little problems instead of a big hard problem. I hope you have your system under a lot of automated tests to make sure all this shuffling doesn't break anything.

Another thing: you talk about shutting down the database. If you're making the changes in a development environment and only making the changes live when you're sure everything works, why would you need to have any downtime in production? I hope you're not thinking about making these changes in production without doing it in development first.

Answer 2

You can use SQLYog (mysql front end) to do it.

Meny option is Powertools -> Database Synchronization wizard

You must be able to open both database remotely (host % should be there)

Answer 3

Been there, done that, and actually in the middle of a similar project right now. With our projects, we inherited a few that we don't know what they are or where everything is, but here is the general flow:

• On new server, set up any appropriate accounts
• Find where to change the server and username/passwords if necessary in the application config
• Shut down the web application so there aren't any writes while moving
• Move the DB
• Reconfigure the app
• Fire it back up
• Repeat for each DB/application

For small stuff, this only takes a few seconds. SQLyog is a great help here. If you have large databases or decide you don't want any downtime, then you need to consider replication.