Chapter Five

Columnar Databases

A columnar DBMS is an implementation of the relational theory, but with a twist. The data storage layer does not contain records. It contains a grouping of columns.

Due to the variable column lengths within a row, a small column with low cardinality or variability of values may reside completely within one block, while another column with high cardinality and longer length may take a thousand blocks. In columnar, all the same data—your data—is there. It’s just organized differently (automatically, by the DBMS).

The main reason why you would want to utilize a columnar approach is simply to speed up the native performance of analytic queries. There is no difference in the SQL or data access tool used to interface ...

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