SQL Server 2022 RC 1 is out! What's new?

Hi Guys,

After an almost exact month from the first release candidate (RC0) a new release candidate has been released.

We talked about the innovations introduced by the RC0 here:SQL Server 2022 RC0, new features and capabilities. The great improvement of the TRIM function, Integrated acceleration and other features 

Now it is time to take a look to this RC 1!

 

 

 

SQL Server 2022 Release Candidate 1

This new release candidate (RC) was announced on September 22, 2022 and has a version number 16.0.950.9

Microsoft also said that the Linux version will be out soon.

This release candidate introduces a feature called Hybrid buffer pool with direct write as well as other improvements.

But, what is the hybrid buffer pool feature?


Hybrid Buffer Pool

The Hybrid Buffer Pool feature was introduced in SQL Server 2019 (15.x) and now is further enhanced in SQL Server 2022 (16.x).

This technology enables buffer pool objects to reference data pages in database files residing on persistent memory (PMEM) devices.

The big plus is that fetching copies of the data pages from disk and caching them in volatile DRAM is no longer necessary.

More in depth, this technology is possible because Persistent memory (PMEM) devices are byte-addressable and so, SQL Server can perform load and store operations against memory maps of the files on the PMEM device. 

With this technology a logical read and a physical read become essentially the same operation be cause Persistent memory devices are accessible via the memory bus just like regular volatile DRAM.

Basically, we went from this architecture ...


..to the following architecture:

 


 

Hybrid Buffer Pool with direct write

 
SQL Server 2022 with this RC 1 takes another step forward by add the Direct Write behavior.

The number of mempcy commands needed to be performed on modified data or index pages residing on PMEM devices are reduced.

It does this by leveraging the durable persisted log buffer as a means to modify the page without having to copy it into one of the DRAM buffer pools. 

Instead pages in database files residing on PMEM devices are modified directly without the need to cache in a DRAM buffer pool and later asynchronously flush to disk. 

It is obviousbly a behavior that adheres to write ahead logging (WAL) semantics becuase the log records in the persisted transaction log buffer have been written to a durable media. 

Microsoft claims that significant performance gains have been observed for transactional workloads using this new feature.

 
That's all for today mates!
 
I hope you enjoyed reading!
~Luke 




 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 

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