Migrations can drop the project, what to do?

Question

MySQL

In my project, I use yii/migrate, once during the deployment I raised the migrations and then it happened. Because of the migrations, the database shut down, after which MySQL fell altogether. The reason was too large table with a large number of records, and in migrations there was ADD COLUMN How to be, how can you make sure in such cases, except for testing?

Answer 1

apart from testing

And what about testing?
If there is a large table, it will change for a long time anyway.
The more - the longer.
To do this, you need to go to those. work and the site to disable.

Answer 2

Because of the migrations, the database shut down, after which MySQL fell altogether.

This is MySQL, it happens to him.

The reason was too large table with a large number of records, and in migrations there was ADD COLUMN How to be, how can you make sure in such cases, except for testing?

I'm not 100% sure (I haven't woken up yet to think too soberly), but it seems to me that there are 2 main options for solving the problem:
1. Do not use MySQL
2. Use replication in MySQL

The reason was too large table with a large number of records

It seems to me that the most likely problem was a too weak machine (memory, processor, disk) for such a volume of database data, and not a too large table :)

Answer 3

You don't need to stop anything.
There is a table T.
The scheme is simple.
1. First, create an empty table T1 with the desired structure. That is, with the column already added.
2. Then we copy the data from T to T1.
3. If the entry in T is very active, then you may have to repeat the copy process for the data that was added while we were copying the original ones.
4. When the copying period becomes small, turn off the data recording in T.
5. Make the final synchronization.
6. Rename T to T_OLD.
A T1 rename to T
7. Enable writing to T