org.apache.hadoop.hive.ql.lib.SubqueryExpressionWalker Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package org.apache.hadoop.hive.ql.lib;
import org.apache.hadoop.hive.ql.parse.ASTNode;
import org.apache.hadoop.hive.ql.parse.HiveParser;
public class SubqueryExpressionWalker extends ExpressionWalker {
/**
* Constructor.
*
* @param disp
* dispatcher to call for each op encountered
*/
public SubqueryExpressionWalker(SemanticDispatcher disp) {
super(disp);
}
/**
* We should bypass subquery since we have already processed and created logical plan
* (in genLogicalPlan) for subquery at this point.
* SubQueryExprProcessor will use generated plan and creates appropriate ExprNodeSubQueryDesc.
*/
protected boolean shouldByPass(Node childNode, Node parentNode) {
if(parentNode instanceof ASTNode
&& ((ASTNode)parentNode).getType() == HiveParser.TOK_SUBQUERY_EXPR) {
ASTNode parentOp = (ASTNode)parentNode;
//subquery either in WHERE IN form OR WHERE EXISTS form
//in first case LHS should not be bypassed
assert(parentOp.getChildCount() == 2 || parentOp.getChildCount()==3);
if(parentOp.getChildCount() == 3 && (ASTNode)childNode == parentOp.getChild(2)) {
return false;
}
return true;
}
return false;
}
}