33 lines
1.5 KiB
Plaintext
33 lines
1.5 KiB
Plaintext
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[[modules-node]]
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== Node
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*elasticsearch* allows to configure a node to either be allowed to store
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data locally or not. Storing data locally basically means that shards of
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different indices are allowed to be allocated on that node. By default,
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each node is considered to be a data node, and it can be turned off by
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setting `node.data` to `false`.
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This is a powerful setting allowing to simply create smart load
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balancers that take part in some of different API processing. Lets take
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an example:
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We can start a whole cluster of data nodes which do not even start an
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HTTP transport by setting `http.enabled` to `false`. Such nodes will
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communicate with one another using the
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<<modules-transport,transport>> module. In front
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of the cluster we can start one or more "non data" nodes which will
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start with HTTP enabled. All HTTP communication will be performed
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through these "non data" nodes.
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The benefit of using that is first the ability to create smart load
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balancers. These "non data" nodes are still part of the cluster, and
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they redirect operations exactly to the node that holds the relevant
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data. The other benefit is the fact that for scatter / gather based
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operations (such as search), these nodes will take part of the
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processing since they will start the scatter process, and perform the
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actual gather processing.
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This relieves the data nodes to do the heavy duty of indexing and
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searching, without needing to process HTTP requests (parsing), overload
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the network, or perform the gather processing.
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