Jan 102014
 

Something a bit different this time. Here’s some formulas relating to databases I’ve learned over the years:

\text{Data anolamies} \propto \frac{1}{\text{Level of Normalization}}

\text{Duplicate rows} \propto \frac{1}{\text{Unique Constraints}}

\begin{array}{ll} \text{Data growth rate} = & \text{Insert Rate} * \text{Indexes} \\ & + \text{"Temporary" tables created} \end{array}

\begin{array}{ll}\text{Database Performance} \propto & \text{Quality of Design} \\ & - \text{Devs with live access} \end{array}

\begin{array}{ll}\forall Databases \exists Developer (IndexingSkills) = & 0 \end{array}

\begin{array}{ll}\text{Uptime}\% = & 100\% \\ & - \text{planned outages} \\ & - \text{hardware failures} \\ & - \text{commands accidentally runs against live} \end{array}

\begin{array}{ll} \text{Password strength} \propto & \text{different characters used}^\text{password length} \\  & - (\text{times sent by email} * \text{post it notes written on})   \end{array}

P(\text{Data loss}\mid\text{No Backups}) = 1

P(\text{Major Outage}\mid\text{Time = 2am})= 1

\begin{array}{ll} P(\text{Outage is your fault}) = & \frac{1}{\text{Time since you last made a change}} \\ & + \frac{1}{\text{Time since you last upset your boss}} \end{array}

If you’ve got any more to add, put them in the comments! :)

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