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MPbase's internal structure is in part based on the concept
of content-addressable memory (CAM). In this information-handling
model, each possible piece of information has one and only one
possible storage location. The data is its own key. It is important
to differentiate CAM from a hash key or traditional index.
With conventional indexing schemes the data content is used with
a hash or index to produce the address location of the data. The
address has no real or direct relationship with the information
contained in the data. With CAM, the data describes its own storage
location. This also means all like data will always be found close
together in the physical data structure. There is a direct relationship
between the information in the data and its location in the physical
data store.
What can this mean for a database? First, any piece of the data
can be used to narrow the search area. Second, all similar data
will be found in close logical proximity. This means that the
data logically closest to any row will be, by definition, the
most similar to it. This makes analysis of the data a much simpler
task. It also speeds the updating process.
With CAM, the final location of any row is predetermined. Normally
the determination of the physical placement is a time-consuming
task. This is why most databases use a separate process for loading
the database. The load process can make bulk decisions, and so
run much faster than the normal update cycle. With a CAM-based
database the data will, to a large extent, "sort itself out"
during the load process.
With an appropriate database architecture using the CAM model,
there is no need for a special load process. The update cycle
is just as efficient as a batch load process would be. Therefore
this type of database is perfect for mass streams of data that
will need to be analyzed. Not only will the update run like a
batch load, but a good portion of the processing needed to analyze
the data is already done.
Why isn't CAM the standard model for database architecture? The
physical storage models currently in use require the data to have
certain characteristics. The tight coupling between logical and
physical location in current DBMSs requires data to be uniformly
spread across the physical media. To allow the data to "bunch
up" is highly undesirable because it creates choke points.
In order to use the CAM model, it was necessary to use a physical storage schema that could benefit from this bunching up. MPbase does just that.
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