Q Tips: Fast, Scalable and Maintainable Kdb+

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You may already know what you want to write about, or you may be at a total loss. Either way, you can settle on a “big book idea” by asking yourself a few simple questions: In 1980, a commercial for the brand featured Betty White, who encouraged people to use them on eyebrows, lips, and ears. “This is a Q-tips cotton swab,” she said. “They call it safe swab.” But the impetus for the switch must have come, at least in part, from an understanding that many people were misusing the cotton swabs. The earliest boxes were intended for baby care, but for decades the product was also pitched for many other tasks – including as an ear cleaning tool for adults.

As our datasets continue to grow, we will reach a point when the amount of data exceeds the available memory on our computer. Chapter15 covers different methods of coping with the problems that big datasets introduce. The chapter discusses how data can be partitioned by columns and rows. It even discusses how kdb+ can be configured to partition the partitions to create a segmented database. The chapter finishes with a discussion on how data can be compressed on disk, mapped into memory and accessed by multiple process. By the end of the book you will have taken a giant leap towards being a seasoned q expert. Not only will you be now well equipped to deciding how to process and store data, but you will also know many intricate details of the language such as how to best use exec statements (giving you far more flexibility than SQL), how to combine data to make analysis efficient and how to write modular statistical functions to help in statistical analysis and simulations. Most importantly, however, you will know how to think in the ‘q way’ – with transparent, terse code, modularity and flexibility through projections and each statements as well as very purposeful decisions in terms of data attributes. You will find that when you ask yourself “what can it do” when it comes to q, you can answer this question not just once, but in multiple ways. Just remember to keep it terse. Chapter17 presents a few advanced techniques. It begins by building a profiling utility to measure the performance of CEP engines. The internal representation of functions and views are discussed. Two forms of derivative pricing are presented and the basics of multi-core processing are demonstrated. The chapter concludes with an example of how to use functional programming techniques to write a histogram library. In the years that followed, many things changed, including the name, which was shortened to just Q-tips; the material, which shifted to paper; and the marketing, which broadened to include all sorts of other household uses. But one thing didn’t: the absence of a warning. Supplied

Some even call it an addiction. On an online forum, Q-tip user associates ear swabbing with dependency: “How can I detox from my Q-tips addiction?” MADtv ran a classic sketch on a daughter having to hide Q-tip use from her parents like a junkie.

Another noteworthy aspect of the book is that it doesn’t treat q purely as a database language but rather a data analysis language. This is a big shift from common perception, as kdb+/q is often compared to SQL and NonSQL databases rather than data processing languages like R and Python. Q Tips tries to show this often-neglected side of the language, giving examples that belong both in a library for data and quantitative analysts in addition to database administrators and developers performing operational support. Not only will you learn how to create and manage various database types available in kdb, you will also know how to create frameworks for aggregating data, multiple ways of summarizing results and a very sophisticated method of creating simulated time series. Crafting doesn’t have to have a purpose. Sometimes it’s just fun to enjoy the creation process. If you are looking for a craft for the spring or summer season, though, this adorable craft is perfect.Ever wondered why earwax can vary in consistency? Thisconsistency can vary person to person and can be influenced by factors like genetics and the environment. Some may have wetter earwax, whilst others might experience drier or flakier earwax. We're here to dissuade you of that notion. While style is great (as long as your prose doesn't start to become purple), substance is far more important when writing a book — hence why you should focus primarily on your plot, characters, conflict(s), and themes. Make sure your book is all killer, no filler Learning q can be challenging for a number of reasons. For some, the terse syntax can be confusing. Regardless of your programming experience, the q syntax will take time to understand and potentially master. The effort you spend learning q will pay dividends in productivity. Yes, writing a lot is important, but it's not more important than your mental health! Remember that writing a book is a marathon, not a sprint, and that a consistent, healthy approach is absolutely vital. Here are some tips for making the most of your writing routine. Don't skip more than one session in a row Pushing wax in, as Q-tips tend to do, can induce hearing loss,” said Fitzgerald. “They can also be inserted too deeply and rupture the ear drum or damage the small middle ear bones, both of which happen more than you would think.”

Let's move on to practical ways that you can improve your writing habits. Word count goals play a huge part in creating an effective writing process, especially if you're trying to finish your book in a certain amount of time. Like many interpreted languages, q has a command line interface or REPL (read-eval-print-loop). If you start q from an interactive terminal (i.e.: shell or DOS prompt), a q) prompt is printed to indicate your input is needed (though this can be turned off with the -q command line argument). There are two important files in the installation. The first file is the q binary itself. It is located in the platform specific folder with a name like w32, s32, v32 or l32. The second file, q.k, is the file that defines many of the q operators. As previously mentioned, q is implemented as a mix of C, k, and q itself. The q.k file includes the implementation for many operators defined in k and q. Over time, a few of the operators previously implemented in q.k have been rewritten directly in C to increase performance. The complete list of operators defined in C can be found in the .Q.res variable. Renowned curator Jacques Saunière staggered through the vaulted archway of the museum's Grand Gallery.” — The Da Vinci Code

Chapter4 explains how to write functions to manipulate and analyze data. It introduces three ways of converting uniformly distributed random numbers to normally distributed random numbers: 12 uniforms, the Box-Muller transform and the Beasley-Springer-Moro method.