Estimating Columnstore Index Size

Niko Neugebauer is somewhat impressed with an update to sp_estimate_data_compression_savings:

The final results were pretty much amazing – 2.1 GB, making the estimation of the sys.sp_estimate_data_compression_savings System Stored Procedure much more precise then my own function! This leaves me very happy and makes me want to investigate and learn how this new stored procedure is capable of providing better estimations.

I decided to test on the other tables within TPCH database and my test on the Orders table have shown a different situation where the 0.7 GB estimation of the sys.sp_estimate_data_compression_savings Stored Procedure were pretty much offbeat when comparing to the CISL dbo.cstore_sp_estimate_columnstore_compression_savings – showing 0.92 GB while the end result was 0.89 GB.
I guess the final answer is that it will depend, but that the estimation of the new stored procedure are not totally offbeat is an incredibly good sign, though I would still keep an eye or even two on the provided estimated results.

Read the whole thing for more details on these examples.

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