public class SemiJoinReductionMerge extends Transform
Semi join reducers are comprised from two parts:
An example of the transformation on three single column semi join reducers is shown below. The plan is simplified for presentation purposes.
/ SEL[fname] - GB1 - RS1 - GB2 - RS2 \ SOURCE - SEL[lname] - GB1 - RS1 - GB2 - RS2 -> TS[Author] - FIL[in_bloom(fname) ^ in_bloom(lname) ^ in_bloom(age)] \ SEL[age] - GB1 - RS1 - GB2 - RS2 /
SOURCE - SEL[fname, lname, age] - GB1 - RS1 - GB2 - RS2 -> TS[Author] - FIL[in_bloom(hash(fname,lname,age)]
Constructor and Description |
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SemiJoinReductionMerge() |
Modifier and Type | Method and Description |
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ParseContext |
transform(ParseContext parseContext)
All transformation steps implement this interface.
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beginPerfLogging, endPerfLogging, endPerfLogging
public ParseContext transform(ParseContext parseContext) throws SemanticException
Transform
transform
in class Transform
parseContext
- input parse contextSemanticException
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