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Type:
Task
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Status: Resolved
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Resolution: Fixed
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Affects Version/s: None
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Fix Version/s: 4.12.0
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Component/s: None
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Labels:
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old issue number:22
Support the standard SQL TABLESAMPLE clause by implementing a filter that uses a skip next hint based on the region boundaries of the table to only return n rows per region.
When TABLESAMPLE clause is used, Phoenix will sample (N) percent of the the hbase table with only O(M) run time complexity. (N is size of table, M is size of stats)
[Update]
Usage:
https://phoenix.apache.org/tablesample.html
Syntax of using table sampling:
select * from PERSON TABLESAMPLE(45);
select count( * ) from PERSON TABLESAMPLE (49) LIMIT 2
Source Code:
https://git-wip-us.apache.org/repos/asf?p=phoenix.git;a=commitdiff;h=5e33dc12bc088bd0008d89f0a5cd7d5c368efa25
- duplicates
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PHOENIX-3294 Support approximate COUNT(*) by using stats.
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- Resolved
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- links to