Think back to the 1960s when time-sharing<\/a> was first introduced or even 1995<\/a> when processors were single core and only about 33 MHz. The average cost of memory was about\u00a0$100 per MB. In those days, every CPU cycle mattered and had a noticeable impact on the performance of the system. Now we have processors whose clock speed has stopped being a direct measure for processing power because of multi-core designs. Windows Server 2016 can support up to 12 TB of main memory!<\/p>\n Back\u00a0in the day<\/em> it was easy to communicate costs. Today it can be a challenge to explain the cost of implementing or enabling a feature.<\/p>\n I once had a difficult discussion with a technically minded business stakeholder. We were going to enable Transparent Data Encryption<\/a>.aspx)\u00a0(TDE). I was asked, \u201c<\/strong>what is the performance impact of enabling TDE?<\/em>*\u201d This person knew enough about computing and encryption to realize that it is not free. I had a couple of responses available, off the top of my head.<\/p>\n All three of those responses were true. #1 and #2 might seem to conflict but they do not.<\/p>\n This system was new. It had only one year worth of production data and it was the prize jewel of the company. There was a lot riding on the success of the system and that translated into funding. When I designed the physical architecture I was allowed to buy\u00a0hardware beyond anything the company had owned before. The result of this was that, with only one year worth of data,\u00a0all the OLTP databases fit into memory (with SSDTs, as well) and there was CPU available for 5 years of 50% annual\u00a0growth.<\/p>\n I knew all of this and understood exactly how wide our bottle necks were. Even though\u00a0TDE\u00a0was going to increase our CPU usage, I was talking to a business stakeholder. No matter how technically minded\u00a0they were, they are concerned with noticeable impacts to the users and business processes. In this case, there was not going to be any impact at all. Weeks after this conversation, heavy load testing showed no measurable impact. The TDE impact fell into the small margin of\u00a0performance fluctuations which occurred due to random user simulations.\u00a0There was a minor up-tick in our server resource use.<\/p>\n In my example, I was intimately familiar with the system that I was talking about. This discussion becomes much more difficult when you are not familiar with the system. Maybe you are giving a presentation and making general comments about a feature, maybe you are a consultant who has only seen the system once so far, or maybe you manage too many servers and can\u2019t be intimate with any one of them.<\/p>\n I attended Chris Bell<\/a>\u2018s Hacking Expose<\/a>\u00a0at a SQL Saturday\u00a0a year or two ago and he faced this same challenge. Without putting exact words into Chris\u2019 mouth, he made a comment about enabling SSL on its performance impact. He was challenged by someone in the audience who fully understood the mechanics of SSL and disagreed with his comment about minimal impact. A short discussion occurred which temporarily disrupted the presentation. The vexing part is that both Chris and the attendee were correct. Neither presented any false statements but\u00a0there was still a minor conflict.<\/p>\n I believe that these conflicts are partly brought about by differences in perspective. Cassy, the DBA,\u00a0who works in a well-funded shop might not allow their servers to go above 60% CPU or always has 20% more memory than is required. Cassy might see a feature as non-impacting while Tiffany, who tunes queries daily to prevent\u00a0the CPU from pegging, might see\u00a0the same impact as completely unacceptable.<\/p>\n No, I do not have a complete solution but I do have a couple of recommendations.<\/p>\nWide-necked bottles<\/h2>\n
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A little background\u2026<\/h3>\n
When your wide-neck is really just a long-neck<\/h2>\n
Do I have a solution?<\/h2>\n
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