Columnar Databases, Data Vaults and EAV Designs are topics engaging a lot of interest right now.
I haven't spent much time reading about them, so I would say that they are simply an example fo the EAV (Entity-Atttribute Value) Approach.
But please Email me if you think I am wrong.
I believe the concept behind Columnar Databases is very simple.
Data is broken down into the lowest level of granularity that is appropriate.
Conventional Relational Database Management Systems ('DBMS') store records contiguously in physical storage.
Every DBMS generates a 'Query Execution Plan' (QEP)which can be explored to identify techniques for improving performance.
The basic technique here is to create Indexes and then check to make sure that the indexes are being used by the DBMS to achieve maximum performance.
Individual DBMS suppliers have come up with techniques for offering improved performance and to achieve a competitive advantage.
Oracle, for example, provides a facility to define 'Hints' which make it possible to say 'For this Query, use the Index called IDX_12345'.
Wikipedia says :-
"... online transaction processing (OLTP)-focused RDBMS systems are more row-oriented, while online analytical processing (OLAP)-focused systems
are a balance of row-oriented and column-oriented.
In practice, row-oriented architectures are well-suited for OLTP-like workloads which are more heavily loaded with interactive transactions.
Column stores are well-suited for OLAP-like workloads (e.g., data warehouses) which typically involve a smaller number of highly complex queries over all data (possibly terabytes).
However, there are a number of proven row-based OLAP RDBMS that handles terabytes, or even petabytes of data, such as Teradata."