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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.optimizer;
import java.util.ArrayList;
import java.util.Stack;
import org.apache.hadoop.hive.ql.exec.FunctionRegistry;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.lib.NodeProcessor;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.ExprNodeColumnDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeConstantDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeFieldDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
/**
* Expression processor factory for pruning. Each processor tries to
* convert the expression subtree into a pruning expression.
*
* It can be used for partition prunner and list bucketing pruner.
*/
public abstract class PrunerExpressionOperatorFactory {
/**
* If all children are candidates and refer only to one table alias then this
* expr is a candidate else it is not a candidate but its children could be
* final candidates.
*/
public static class GenericFuncExprProcessor implements NodeProcessor {
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
ExprNodeDesc newfd = null;
ExprNodeGenericFuncDesc fd = (ExprNodeGenericFuncDesc) nd;
boolean unknown = false;
if (FunctionRegistry.isOpAndOrNot(fd)) {
// do nothing because "And" and "Or" and "Not" supports null value
// evaluation
// NOTE: In the future all UDFs that treats null value as UNKNOWN (both
// in parameters and return
// values) should derive from a common base class UDFNullAsUnknown, so
// instead of listing the classes
// here we would test whether a class is derived from that base class.
// If All childs are null, set unknown to true
boolean isAllNull = true;
for (Object child : nodeOutputs) {
ExprNodeDesc child_nd = (ExprNodeDesc) child;
if (!(child_nd instanceof ExprNodeConstantDesc
&& ((ExprNodeConstantDesc) child_nd).getValue() == null)) {
isAllNull = false;
}
}
unknown = isAllNull;
} else if (!FunctionRegistry.isDeterministic(fd.getGenericUDF())) {
// If it's a non-deterministic UDF, set unknown to true
unknown = true;
} else {
// If any child is null, set unknown to true
for (Object child : nodeOutputs) {
ExprNodeDesc child_nd = (ExprNodeDesc) child;
if (child_nd instanceof ExprNodeConstantDesc
&& ((ExprNodeConstantDesc) child_nd).getValue() == null) {
unknown = true;
}
}
}
if (unknown) {
newfd = new ExprNodeConstantDesc(fd.getTypeInfo(), null);
} else {
// Create the list of children
ArrayList children = new ArrayList();
for (Object child : nodeOutputs) {
children.add((ExprNodeDesc) child);
}
// Create a copy of the function descriptor
newfd = new ExprNodeGenericFuncDesc(fd.getTypeInfo(), fd.getGenericUDF(), children);
}
return newfd;
}
}
/**
* FieldExprProcessor.
*
*/
public static class FieldExprProcessor implements NodeProcessor {
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
ExprNodeFieldDesc fnd = (ExprNodeFieldDesc) nd;
boolean unknown = false;
int idx = 0;
ExprNodeDesc left_nd = null;
for (Object child : nodeOutputs) {
ExprNodeDesc child_nd = (ExprNodeDesc) child;
if (child_nd instanceof ExprNodeConstantDesc
&& ((ExprNodeConstantDesc) child_nd).getValue() == null) {
unknown = true;
}
left_nd = child_nd;
}
assert (idx == 0);
ExprNodeDesc newnd = null;
if (unknown) {
newnd = new ExprNodeConstantDesc(fnd.getTypeInfo(), null);
} else {
newnd = new ExprNodeFieldDesc(fnd.getTypeInfo(), left_nd, fnd.getFieldName(),
fnd.getIsList());
}
return newnd;
}
}
/**
* Processor for column expressions.
*/
public static abstract class ColumnExprProcessor implements NodeProcessor {
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
ExprNodeDesc newcd = null;
ExprNodeColumnDesc cd = (ExprNodeColumnDesc) nd;
newcd = processColumnDesc(procCtx, cd);
return newcd;
}
/**
* Process column desc. It should be done by subclass.
*
* @param procCtx
* @param cd
* @return
*/
protected abstract ExprNodeDesc processColumnDesc(NodeProcessorCtx procCtx,
ExprNodeColumnDesc cd);
}
/**
* Processor for constants and null expressions. For such expressions the
* processor simply clones the exprNodeDesc and returns it.
*/
public static class DefaultExprProcessor implements NodeProcessor {
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
if (nd instanceof ExprNodeConstantDesc) {
return ((ExprNodeConstantDesc) nd).clone();
}
return new ExprNodeConstantDesc(((ExprNodeDesc)nd).getTypeInfo(), null);
}
}
/**
* Instantiate default expression processor.
* @return
*/
public static final NodeProcessor getDefaultExprProcessor() {
return new DefaultExprProcessor();
}
/**
* Instantiate generic function processor.
*
* @return
*/
public static final NodeProcessor getGenericFuncProcessor() {
return new GenericFuncExprProcessor();
}
/**
* Instantiate field processor.
*
* @return
*/
public static final NodeProcessor getFieldProcessor() {
return new FieldExprProcessor();
}
}
