Jeff Moden (11/15/2012)
I hear ya!!! If the final PreaggregatedHierarchy table is the source of information for a 24/7/.999999999 web site or application, then you really can’t afford even the 62 seconds of downtime especially if you’re running a world wide Multi-Level Marketing company! You really don’t want to make any of the members angry with even a minute of “downtime” while you rebuild the table.So what do you do?
It’s simple. Have a synonym (or pass-through view) pointing at the current version of the pre-aggregated hierarchy table while you build up a new version. Once completed, simply repoint the synonym or view to the new table and drop the old table (or keep it to do monthly comparisons for a month). The total “downtime” is now measured in milli-seconds.
Next month, you do the same thing. Just keep “flip-flopping” the synonym or view between the two tables.
You can even include the building of the Primary Key in an online fashion like this IF you let the system name the PKs for you instead of adding them as a “named constraint”. Adding the other indexes are a piece of cake because index names don’t need to be unique in a database like constraints need to be.
Hi Jeff,
I was wondering if you could elaborate on the above with some code examples or references.
Now that I seem to understand your Hierarchies on Steroids after about 3 readings, I'm anxious to learn more.
My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.
Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
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