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Day: November 19, 2015

Partition Elimination

Kendra Little talks partition elimination:

Working with table partitioning can be puzzling. Table partitioning isn’t always a slam dunk for performance: heavy testing is needed. But even getting started with the testing can be a bit tricky!

Here’s a (relatively) simple example that walks you through setting up a partitioned table, running a query, and checking if it was able to get partition elimination.

I would have snipped the tl;dr section but it was too long…

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MDX On DirectQuery

Chris Webb takes a look at MDX querying in SQL Server 2016 Tabular models:

There were a lot of limitations when using DirectQuery in SSAS Tabular 2012/4, but for me the showstopper was the fact that it only worked if you were running DAX queries against your model. Historically the only major client tool that generated DAX queries to get data was Power View, and Power View was/is too limited for serious use, so that alone meant that none of my customers were interested in using DirectQuery. Although we now have Power BI Desktop and, which also generate DAX queries, the fact remains that the vast majority of business users will still prefer to use Excel PivotTables as their primary client tool – and Excel PivotTables generate MDX queries. So, support for MDX queries in DirectQuery mode in SSAS 2016 means that Excel users will now be able to query a Tabular model in DirectQuery mode. This, plus the performance improvements made to the SQL generated in DirectQuery mode, means that it’s now a feature worth considering in scenarios where you have too much data for SSAS Tabular’s native in-memory engine to handle or where you need to see real-time results.

Good stuff.  Read the whole post, especially if (unlike me) you know a thing or two about MDX.

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Shaw On Transactions, Part 2

Gail Shaw has part 2 of her transactions series up:

Again, exactly the desired behaviour. The changes made in the outer procedure were committed, the changes in the inner procedure, the procedure where the error was thrown, were rolled back.

Used correctly, savepoints can be a powerful mechanism for managing transactions in SQL Server. Unfortunately they’re not well known and as such their use can also make code much harder for later developers to debug.

I’ve used conditional transactions fairly regularly (procedures can have calling parent procedures, or sometimes can be called on their own), but never savepoints.

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Auto-Name SSDT Constraints

Ed Elliott has created a tool to auto-name constraints in SQL Server Data Tools:

I have released a tool that will do just that, if you grab the SSDT-Dev Pack at least version 1.1 from this adds a new menu to the tools menu in visual studio to name constraints. What I like to do is to go to “tools->options–>keyboard” and map an unused short-cut to the command “Tools.NameConstraints”, I used “ctrl+k + ctrl+n” so I can open a table in SSDT and just do ctrl+k and then ctrl+n and it automatically re-writes any tables in the active document that have unnamed primary keys with an appropriate name.

Grab the code or release binary at his Github repo.

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