Which statement is correct when describing Range Clustered Tables (RCT) as compared to
regular base tables that use at least one index?
A.
RCTs require less logging, less buffer pool space, and less maintenance.
B.
RCTs require more logging, less buffer pool space, and more maintenance.
C.
RCTs require less logging, more buffer pool space, and less maintenance.
D.
RCTs require more logging, more buffer pool space, and less maintenance.
Explanation:
There are some advantages to using range-clustered tables.
Direct access
Access is through a range-clustered table key-to-RID mapping function.
Less maintenance
A secondary structure such as a B+ tree does not need to be updated for every INSERT, UPDATE, or DELETE.
Less logging
There is less logging done for range-clustered tables when compared to a similarly sized regular table and associated B+ tree index.
Less buffer pool memory required
There is no additional memory required to store a secondary structure.
Order properties of B+ tree tables
The ordering of the records is the same as what was achieved by B+ tree tables without requiring extra levels or B+ tree next-key locking schemes. With RCT, the code path length is reduced compared to regular B+ tree indexes. To obtain this advantage, however, the range-clustered table must be created with DISALLOW OVERFLOW and the data must be dense, not sparse.
One less index
Mapping each key to a location on disk means that the table can be created with one less index than would have been necessary otherwise. With range-clustered tables, the application requirements for accessing the data in the table might make a second, separate index unnecessary. You may still choose to create regular indexes, especially if the application requires it.
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