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Querying Data From HBase
• By Row-Id or range of Row Ids
– Only load the specific rows with the provided range of ids
– Only touch the region servers with those ids
– If no further criteria provided will load all the cells for all
of the families which means loading multiple files of
HDFS
• By Column Family
– Eliminates the needs to load other storage files
– Strongly suggested parameter if you know the needed
families
• By Timestamp/Version
– Can skip entire store files as the contained timestamp
range within a file is considered
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Querying Data From HBase
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• By Column Name/Qualifier
– Will not eliminate the need to load the storage file
– Will however eliminate the need to transfer the unwanted data
• By Value
– Can skip cells by using filters
– The slowest selection criteria
– Will examine each cell
• Filters can be applied to each selection criteria
– rows, families, columns, timestamps and values
• Multiple querying criteria can be provided
– And most of the time should be provided