Continuing on with my Partitioning post series, this is part 7.
The partitioning includes several major components of work (and can be linked below);
- partitioning large existing non-partitioned tables
- measuring performance impacts of partitioned aligned indexes
- measuring performance impacts of DML triggers for enforcing partitioned unique indexes
- rebuilding tables that are already partitioned (ie. apply a new partitioning scheme)
- implementing partial backups and restores (via leveraging partitions)
- implementing partition aware index optimisation procedures
- Calculating table partition sizes in advance
This blog post deals with calculating partitioning sizes in advance.
Sometimes (just sometimes) you need to calculate the size your table partitions upfront before you actually go to the pain and effort of partitioning (or repartition) a table. Doing this helps with pre-sizing the database files in advance instead of having them auto-grow many many times over in small increments as you cut data over into the partitions.
As a quick aside…
- The negative performance impacts of auto-shrink are universally well known (er, for DBA’s that is!), however I rarely hear people talk about the less universally well known negative performance impacts of auto-grow quite so much.
- Auto-Growing your database files in small increments can cause physical fragmentation in the database files on the storage subsystem and cause reduced IO performance. If you are interested you can read about this here https://support.microsoft.com/en-us/kb/315512
Now – back to what I was saying about pre-sizing table partitions…!
I prepared a SQL script which given some parameters can review an existing table and its indexes (whether they are already partitioned or not) and tell you what your partition sizing breakdown would be should that table be partitioned with a given partition function.
I wrote it just for what I needed but it could be expanded more if you are feeling energetic. The script is at the end of this post.
And so, lets get into the nitty gritty of this estimation script!