Apache Kylin : Analytical Data Warehouse for Big Data
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Background
Kylin will generate cuboid statistics of segments in a cube during the cube building; Besides, when optimizing and merging cubes, statistics will update too.
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- If Kyllin4 does not has a base cuboid for a cube, then the base cuboid "1111...111" row will be 0 and the size is 0.0 MB.
- If a cuboid does not exist, then its children will show the shrink percentage to be "-0.0 %".
- the command can only check a cube every time.
Example for estimate statistics
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# bin/kylin.sh org.apache.kylin.engine.mr.common.CubeStatsReader kylin_sales_cube Retrieving hadoop conf dir... Retrieving Spark dependency... ... Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=512M; support was removed in 8.0 ... ============================================================================ Statistics of kylin_sales_cube[20120101000000_20130201000000] Total cuboids: 160 Total precise rows: 828158 Total precise size(MB): 30.2807559967041 Sampling percentage: 100 Mapper overlap ratio: -1.0 Mapper number: -1 Length of dimension DEFAULT.KYLIN_SALES.BUYER_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.SELLER_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.TRANS_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.PART_DT is 3 ... |---- Cuboid 111111111111111111, est row: 5402, precise MB: 0.22 |---- Cuboid 000111111111111111, est row: 5402, est MB: 0.22, shrink: 100% |---- Cuboid 000101111111111111, est row: 5402, est MB: 0.21, shrink: 100% |---- Cuboid 000101101111111111, est row: 5402, est MB: 0.2, shrink: 100% |---- Cuboid 000101001111111111, est row: 5402, est MB: 0.19, shrink: 100% |
Example for precise statistics
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# bin/kylin.sh org.apache.kylin.engine.mr.common.CubeStatsReader kylin_sales_cube Retrieving hadoop conf dir... Retrieving Spark dependency... ... Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=512M; support was removed in 8.0 ... ============================================================================ Statistics of kylin_sales_cube[20120101000000_20130201000000] Total cuboids: 160 Total precise rows: 828158 Total precise size(MB): 30.2807559967041 Sampling percentage: 100 Mapper overlap ratio: -1.0 Mapper number: -1 Length of dimension DEFAULT.KYLIN_SALES.BUYER_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.SELLER_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.TRANS_ID is 4 Length of dimension DEFAULT.KYLIN_SALES.PART_DT is 3 ... |---- Cuboid 111111111111111111, precise row: 0, precise MB: 0 |---- Cuboid 000111111111111111, precise row: 5402, precise MB: 0.22, shrink: -0% |---- Cuboid 000101111111111111, precise row: 5402, precise MB: 0.21, shrink: 100% |---- Cuboid 000101101111111111, precise row: 5402, precise MB: 0.2, shrink: 100% |---- Cuboid 000101001111111111, precise row: 5402, precise MB: 0.19, shrink: 100% |
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