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For some reason, this came to mind: under the sea, under the sea. That's what I thought of as I was reading about Microsoft sinking a data center. There are probably jokes to be made about Microsoft and sinking, though they're less humorous as the company's stock price has risen quite a bit in the last few years. 

The is a research project from Microsoft on future data center design. Using modular devices that can be submerged for years at a time, only having a connection for power and data back to the surface. These are designed as sealed environments, without the creature comforts needed in data centers for human technicians. The systems inside are built to live on their own, using the water for cooling the heat generated by computations.

There won't be any repairs or replacements for failures. With the equivalent of twelve racks of servers in the system, I wonder how long they will list. I find it interesting that the experiment is designed for a year, though the device should have a timeline of 5 years. Does that mean that Microsoft expects current hardware to last for five years? Is that the new lifecycle of modern chips and storage? Or perhaps they find the lifecycle is shorter, but this is more a test of the extreme lifetime that they expect and they'll track and chart the failures across time of components? I expect they already know some of the expected lifetime of hardware from their massive Azure data centers, which they can compare to this environment.

It's an interesting idea, and one that might see smaller, modular data centers spread around bodies of water where there is enough movement to carry heat away. This should reduce power consumption, as less is needed for cooling. This can also reduce latency, with devices perhaps located closer to clients for heavy compute capabilities or even content delivery.

I'm not sure these will work at larger scales, as heat attracts life, with plant and animals potentially migrating to be near the submersibles. Who knows if were would be interference with operations, but I wouldn't be surprised to find that some level of maintenance is needed. We might see the rise of a new type of job, like undersea gardener or window washer that keeps the submarines clear of encroaching biology.

Of course, I wouldn't be surprised to see Roomba-like automated devices that put many of these humans out of work.

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UNION will perform an implicit DISTINCT over the whole result set, so even if there are no duplicates between the first and the second queries, the UNION operator will remove the double (1) from the final result.

There is no need to write something as

 SELECT DISTINCT * FROM (VALUES (1), (2), (3), (1)) AS t1(id) UNION SELECT DISTINCT * FROM (VALUES (4), (5)) AS t2(id)

although I've seen such code very often.

If you compare the execution plans of those queries on real tables, you'll find out, that the one with the additional manual keywords has a little bit higher CPU load (depending on your indexes / table sizes) because of the additional distinct sort or hash aggregate.

Ref: UNION - click here

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