Entropy

Entropy is a measure of disorder. Software usually becomes more difficult and costly to maintain over time. Its entropy tends to increase as a result. Note to myself: The Boy Scout Rule, code refactoring and paying technical debt help reducing software entropy.

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Lexical scope

In a nested group of functions, the inner functions have access to the variables and other resources of their parent scope. This means that the child functions are lexically bound to the execution context of their parents. Lexical scope is sometimes also referred to as static scope. Source: https://stackoverflow.com/a/53062093

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Selectivity

Selectivity is the number of unique values produced by an operation (e.g. an index scan or filter), relative to the total number of rows. The higher the selectivity, the more likely PostgreSQL is able to use an index. Source: https://docs.gitlab.com/ee/development/understanding_explain_plans.html#cardinality-and-selectivity

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