2.6.2 Data distribution with grouped keys
If a data item has a defined group name, its storage EADS server is determined by the hash value of that group name.
If groups have hierarchies, the storage EADS server is determined by the hash value of the first group hierarchy name. Multiple data items with the same first group hierarchy name are stored on the same EADS server because their hash values are the same.
For example, the data items with the following keys are stored on the same EADS server:
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Group1:Group2:ElementA
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Group1:Group3:ElementB
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Group1:ElementC
For an overview of data distribution, see 2.5 Data distribution by consistent hashing.
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You can also group keys by specifying the EADS server ID of the storage EADS server. Such a group is called an EADS server ID specified group. If you use EADS server ID specified groups to group keys, specify the EADS server ID enclosed in square brackets ([]) at the beginning of the keys (at the beginning of the highest group hierarchy name).
For example, the key data shown below belongs to group [1]Group1 and is stored in the EADS server whose EADS server ID is 1 (any character string following the EADS server ID, such as Group1, is ignored and the storage EADS server is determined only by the specified EADS server ID).
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[1]Group1:Group2:ElementA
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[1]Group1:Group3:ElementB
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[1]Group1:ElementC
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