New Resumable Online Index Create SQL Server 2019

SQL Server 2019 brings a very exciting new feature that was long overdue. Resumable Online Index Creation is one of my favorite new things. This, when paired with Resumable Index Rebuilds introduced with SQL Server 2017, really gives database administrators much more control over the index processes.

Have you ever started to build a new index on a very large table only to have users call and complain their process is hung, not completing, or the system is slow? That’s when you realize you’re the cause because you tried to sneak in a new index. I have many times; because creating a new index can impact the performance and can be a problematic process for users when you have no or little downtime windows available. When you kill the create process, it rolls back requiring you to start from the beginning the next time. With resumable Online Index Creation, now you have the ability to pause and restart the build at the point it was paused. You can see where this can be very handy.

To use this option for creating the index, you must include "RESUMABLE=ON".

CREATE INDEX MyResumableIndex ON MyTable (MyColumn) WITH (ONLINE=ON, RESUMABLE=ON, MAX_DURATION=30)

Let’s say you have only two 30-minute windows available to create this new index over the next two days. You could use the MAX_DURATION option with the new RESUMABLE=ON to specify the time interval for an index being built. Once the 30-minute time is up, the index building automatically gets paused if it has not been completed. When you’re ready the next day, you can RESUME right where it left off, allowing you to complete the process. Very cool.

Another added benefit is managing transaction log growth. As we all know, creating indexes, especially large ones, can cause hefty log growth events and can unfortunately lead to running out of disk space. This new functionality allows us to better manage that. We can now pause the process and truncate or back up the log mid-process building the index in chunks.

In the case of when you create an index only to get complaints from users or manage your log growth, you can simply do the below to PAUSE and restart it when a time is better, or your transaction log maintenance has been completed.

You can KILL the SPID creating the index or run the below.

ALTER INDEX MyResumableIndex ON MyTable PAUSE;

To restart

ALTER INDEX MyResumableIndex ON MyTable RESUME; Or simply re-execute your CREATE INDEX statement

According to MSDN, the Resumable online index supports the following scenarios.

• Resume an index creation operation after an index creation failure, such as after a database failover or after running out of disk space.
• Pause an ongoing index creation operation and resume it later allowing to temporarily free system resources as required and resume this operation later.
• Create large indexes without using as much log space and a long-running transaction that blocks other maintenance activities and allows log truncation.

Note. SORT_IN_TEMPDB=ON is not supported when using RESUMABLE=ON.

Once you pause it, how do you know how far the index got and how much is left to be created? With the Resumable REBUILD Index feature added in SQL Server 2017, we have also got a new sys.index_resumable_operations system view. This view shows us the percentage complete, current state, start time, and last pause time.

I am very excited about this new Index Create feature. I think this is a big WIN for SQL Server 2019.