Database Reference
In-Depth Information
• DataNodes are the salves with the following functions:
• Blocks storage using the underlying OS's files
• Access to the blocks is given to the clients directly from DataNodes
• Communication of status and health to the NameNode periodically
• Checks for block integrity periodically
Hadoop MapReduce
Hadoop MapReduce function and flow is depicted in the following figure. There are a
series of functions that are executed within the MapReduce flow
Mapper
|
Combin-
er
|
Partitioner
|
Shuffle and Sort
|
Reducer
. Few of the functions in the flow can
be implicit (have a default behavior, if not coded for).
Hadoop enables the data scientists to create MapReduce jobs quickly and efficiently.
The screenshot below shows
Greenplum Command Center
with database and HD
modules installed.
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