Will scale Azure DB from Web To new tier cause availability issue

Question

As far as I can tell, scaling an Azure DB from the retired tiers to the new tiers is simply a matter of using the scale function in the Azure portal.

What I cannot seem to find anywhere is a definitive answer as to whether there are any connection string changes required (or any other issues that could cause unavailability) when scaling from the retired to new tiers.

I have a production database that needs to be upgraded, service interruption would be very bad.

Answer 1

The scale operation will not change the connection string. You could face some (very small, but) finite amount of downtime while the switchover happens.

Please refer to the documentation for details. Note that you will be have to suspend geo-replication (if already enabled) for the duration of the upgrade.

Answer 2

Techincaly it will be the same server, same connection string, same everything, but version and features.

But I would be concerned about the following statement from docu:

The duration of upgrade depends on the size, edition and number of databases in the server. The upgrade process can run for hours to days for servers especially for servers that has databases:

• Larger than 50 GB, or
• At a non-premium service tier

Which is kind of concerning.

What I would do, if possible is:

1. Put my service into read-only mode (put on hold any writes to the DB)
2. Create new db in same server from the existing one with the command - CREATE DATABASE AS COPY OF ...
3. When creation of DB is ready, export the new db to backpac and delete the DB when export is ready.
4. Perform upgrade.

In theory you could do the process without putting your system into Read-Only mode, but I am just taking more precautions measures.

And yes, you also have to aware that you are upgrading your Azure SQL DB Server not just a single Database.