science

Super column family

Super column family is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Super column family rather than just read about it. In short: A super column family is a NoSQL object that contains column families. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that are column families.

Key takeaways

Super column family belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Super column family to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Super column family from memory before moving on to harder problems.

Reference excerpt

A super column family is a NoSQL object that contains column families. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that are column families. In analogy with relational databases, a super column family is something like a "view" on a number of tables. It can also be seen as a map of tables.

Benefits It is useful when making a data model to have some kind of a view on a number of tables. Using a super column family is something similar to that in distributed data stores. There are, however, no "joins" between the "tables", as data stores like Apache Cassandra are non-relational.

Sorting and querying There is no way to sort super columns after they have been inserted, nor to query an arbitrary query in distributed data stores. Super columns are sorted when they are added to the column family, and it is also possible to use a different sorting attribute for the contained columns of a super column. Similar to the standard column family, sorting is defined by an attribute. This attribute is called the CompareSubcolumnsWith in Apache Cassandra and have the following values:

AsciiType BytesType LexicalUUIDType LongType TimeUUIDType UTF8Type Although it is possible to sort the super columns in a way, the columns inside the super columns another way, it is not allowed to treat part of the super columns in a special way.

Code example Here is an example of a super column family that contains other column families:

Where "Cath" and "Terry" are row keys; "username", "address", and "account" are super column names; and "firstname", "lastname", "city", etc. are column names.

Illustrations

Worked examples

Example 1 — a first encounter with Super column family

Start with the simplest possible case. Write down what Super column family claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Super column family before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Super column family ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Super column family

In research: Super column family appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Super column family in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Super column family is common in secondary-school and first-year university syllabi. It links to neighbouring topics Database stubs, Distributed data stores, NoSQL, so understanding it makes those chapters shorter.
In everyday life: Look for Super column family outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Super column family in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Super column family means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Super column family out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Super column family in simple terms?

A super column family is a NoSQL object that contains column families. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that are column families.

Why does Super column family matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Super column family?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Super column family.