Real Time Information Director User Documentation

Technical Overview of the Real Time Information Director
Hewlett-Packard Company 8 529618 - 002
The advantage of artificial partitioning is that the Director can use your knowledge of
how the data is typically accessed to help ensure that the data is both evenly distributed
and efficiently clustered.
The logical key of a table can be either a natural key--data present in the input record,
for example a customer name--or an artificial key assigned by the Director. The
Director supports artificial partitioning for both kinds of tables but can use different
partitioning strategies, depending on the kind of key.
In the case of an artificial key, the Director can use any of the following partitioning
strategies. (You use metadata to specify which strategy to use for each table.)
• Round robin partitioning. Each new record of a given type is assigned the next
partition in a repeating sequence. This strategy ensures even distribution but does
nothing (by itself) to cluster the data. This strategy is especially suitable for
master data, for example a data table representing a customer, a product, or a
factory.
• Parent-child affinity. A new record is assigned the same partition ID as the parent
record in the document. This strategy helps to cluster the data, at least when the
data is first inserted. Note that the relationship between this child record and the
parent record might be temporary and non-exclusive. For example, a single
account might be associated with multiple customers, with different partition IDs,
and customers might, over time, be added or dropped from the account.
• Key affinity. A new record is assigned the same partition ID used by a related
record in another artificially partitioned table. This strategy insures that the data
is clustered in a way that is optimal for the future. You can use key affinity only
if the new record is permanently and exclusively associated with the related
record: that is, if you would never need to associate the record with a different
record in the same table with a different partition ID. (An example is a debit or
credit to an account.) There are two types of key affinity strategies. System key
affinity is used if the related table has an artificial key. Natural key affinity is
used if the related table has a natural key.
Given the partition ID, the Director assigns an artificial key, also known as a system key.
The Director divides the key space by partition, so the partition ID can always be
deduced from the system key.
In the case of a natural key, the Director assigns the partition ID by hashing on the logical
key or by using a key affinity strategy. Hashing provides even distribution, and key
affinity helps cluster the data.
To realize the goals of partitioning, a database administrator uses the partition IDs
assigned by the Director as a basis for partitioning the data physically across the system.