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https://issues.apache.org/jira/browse/HBASE-4435?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nichole Treadway updated HBASE-4435:
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Description:
Adds in a Group By -like functionality to HBase, using the Coprocessor
framework.
It provides the ability to group the result set on one or more columns (groupBy
families). It computes statistics (max, min, sum, count, sum of squares, number
missing) for a second column, called the stats column.
To use, I've provided two implementations.
1. In the first, you specify a single group-by column and a stats field:
statsMap = gbc.getStats(tableName, scan, groupByFamily, groupByQualifier,
statsFamily, statsQualifier, statsFieldColumnInterpreter);
The result is a map with the Group By column value (as a String) to a
GroupByStatsValues object. The GroupByStatsValues object has max,min,sum etc.
of the stats column for that group.
2. The second implementation allows you to specify a list of group-by columns
and a stats field. The List of group-by columns is expected to contain lists of
{column family, qualifier} pairs.
statsMap = gbc.getStats(tableName, scan, listOfGroupByColumns,
statsFamily, statsQualifier, statsFieldColumnInterpreter);
was:Adds in a Group By -like fucntionality to HBase using coprocessors
> Add Group By functionality using Coprocessors
> ---------------------------------------------
>
> Key: HBASE-4435
> URL: https://issues.apache.org/jira/browse/HBASE-4435
> Project: HBase
> Issue Type: Improvement
> Components: coprocessors
> Reporter: Nichole Treadway
> Priority: Minor
> Attachments: HBase-4435.patch
>
>
> Adds in a Group By -like functionality to HBase, using the Coprocessor
> framework.
> It provides the ability to group the result set on one or more columns
> (groupBy families). It computes statistics (max, min, sum, count, sum of
> squares, number missing) for a second column, called the stats column.
> To use, I've provided two implementations.
> 1. In the first, you specify a single group-by column and a stats field:
> statsMap = gbc.getStats(tableName, scan, groupByFamily,
> groupByQualifier, statsFamily, statsQualifier, statsFieldColumnInterpreter);
> The result is a map with the Group By column value (as a String) to a
> GroupByStatsValues object. The GroupByStatsValues object has max,min,sum etc.
> of the stats column for that group.
> 2. The second implementation allows you to specify a list of group-by columns
> and a stats field. The List of group-by columns is expected to contain lists
> of {column family, qualifier} pairs.
> statsMap = gbc.getStats(tableName, scan, listOfGroupByColumns,
> statsFamily, statsQualifier, statsFieldColumnInterpreter);
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