The biggest advantage of a pure column-oriented DBMS comes from having the positional information indirectly available without the requirement to store this ID information. During query execution the required position lists can then be generated.
In addition. If you considere the record format of traditional row-oriented databases you will see that the overhead of storing a single attribute record is rather high. Since with column-oriented DBMS its all about IO performance (Disk/Memory, Memory/CPU) such overhead can diminish the advantage.
Thus typical column stores tend to use only single strings of sequential memory to store the data. This can even be enhanced by applying dictionary compression and as a result only storing integer values. And modern CPUs are good in processing lots of them.
Comments
The biggest advantage of a pure column-oriented DBMS comes from having the positional information indirectly available without the requirement to store this ID information. During query execution the required position lists can then be generated.
In addition. If you considere the record format of traditional row-oriented databases you will see that the overhead of storing a single attribute record is rather high. Since with column-oriented DBMS its all about IO performance (Disk/Memory, Memory/CPU) such overhead can diminish the advantage.
Thus typical column stores tend to use only single strings of sequential memory to store the data. This can even be enhanced by applying dictionary compression and as a result only storing integer values. And modern CPUs are good in processing lots of them.