Migrated DB to SQL Azure very slow

Question

Hi!

I migrated a quite simple DB from SQL 2016 to SQL Azure PaaS.

The app server using the DB is also in Azure, same location and RG.

Now when running queries it is extremely slow. Both from the app server, and I also did a test creating 750000 rows:

-onprem server: 5,38 min
-SQL Azure: 42,27 min

All the time the utilization of resources (CPU/IO) are very low (0-3%)

Answer 1

This is typical scenario.

Once you have migrated, make sure you defragment all indexes and update all statistics using Ola Hallengren scripts. Use Azure Automation to make this a daily task.

After that, create missing indexes reported by the T-SQL script shown on this article.

After that you will see performance improvements.