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The Cost of Empty Partitions in SQL Server

Aaron Bertrand reminds us that TANSTAAFL:

Not too long ago, I came across a table that had 15,000 partitions—all but 4 of them empty. I bet when you have implemented partitioning you, too, have wondered: “Why shouldn’t I create all future partitions now?”

The question is valid: wouldn’t maintenance be easier if you only had to phase out old partitions, without ever worrying about adding partitions to accommodate new data?

Here’s the thing. Microsoft will never tell you this, but empty partitions are not free. I don’t mean you will get an invoice for creating too many, but you will pay for them in other ways.

I think the reason people do this sort of thing is that partition management is harder than it really needs to be in SQL Server. Adopting the partitioning process for dedicated SQL pools in Azure Synapse Analytics would be a good start but consider that partitions are almost always date or numeric intervals (often pseudo-date numbers like 20220601 to represent June 1, 2022) and allow people to create partitions based on the key and have the system manage it. I’m being vague and hand-wavey and not talking about all of the edge cases (like if some dope puts in a date for 22220601 instead of 20220601) but I think some PARTITION RANGE RIGHT ON [DateWK] INTERVAL MONTHLY WITH MAX_FUTURE_PARTITIONS=2, MAX_MAINTAINED_PARTITIONS=48, PARTITION_ARCHIVAL_TABLE=History.MyTable or something like that would cut to the core of what partition management does without writing thousand-line scripts full of dynamic SQL trying to manage these things.

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