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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.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.conf.HiveConf.ConfVars;
import org.apache.hadoop.hive.ql.exec.FilterOperator;
import org.apache.hadoop.hive.ql.exec.GroupByOperator;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.OperatorFactory;
import org.apache.hadoop.hive.ql.exec.ReduceSinkOperator;
import org.apache.hadoop.hive.ql.exec.SelectOperator;
import org.apache.hadoop.hive.ql.exec.TableScanOperator;
import org.apache.hadoop.hive.ql.lib.DefaultGraphWalker;
import org.apache.hadoop.hive.ql.lib.DefaultRuleDispatcher;
import org.apache.hadoop.hive.ql.lib.Dispatcher;
import org.apache.hadoop.hive.ql.lib.GraphWalker;
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.lib.Rule;
import org.apache.hadoop.hive.ql.lib.RuleRegExp;
import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.metadata.Table;
import org.apache.hadoop.hive.ql.parse.OptimizeTezProcContext;
import org.apache.hadoop.hive.ql.parse.ParseContext;
import org.apache.hadoop.hive.ql.parse.PrunedPartitionList;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.AggregationDesc;
import org.apache.hadoop.hive.ql.plan.DynamicPruningEventDesc;
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.ExprNodeDynamicListDesc;
import org.apache.hadoop.hive.ql.plan.FilterDesc;
import org.apache.hadoop.hive.ql.plan.GroupByDesc;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
import org.apache.hadoop.hive.ql.plan.PlanUtils;
import org.apache.hadoop.hive.ql.plan.SelectDesc;
/**
* This optimization looks for expressions of the kind "x IN (RS[n])". If such
* an expression made it to a table scan operator and x is a partition column we
* can use an existing join to dynamically prune partitions. This class sets up
* the infrastructure for that.
*/
public class DynamicPartitionPruningOptimization implements NodeProcessor {
static final private Log LOG = LogFactory.getLog(DynamicPartitionPruningOptimization.class
.getName());
public static class DynamicPartitionPrunerProc implements NodeProcessor {
/**
* process simply remembers all the dynamic partition pruning expressions
* found
*/
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
ExprNodeDynamicListDesc desc = (ExprNodeDynamicListDesc) nd;
DynamicPartitionPrunerContext context = (DynamicPartitionPrunerContext) procCtx;
// Rule is searching for dynamic pruning expr. There's at least an IN
// expression wrapping it.
ExprNodeDesc parent = (ExprNodeDesc) stack.get(stack.size() - 2);
ExprNodeDesc grandParent = stack.size() >= 3 ? (ExprNodeDesc) stack.get(stack.size() - 3) : null;
context.addDynamicList(desc, parent, grandParent, (ReduceSinkOperator) desc.getSource());
return context;
}
}
private static class DynamicListContext {
public ExprNodeDynamicListDesc desc;
public ExprNodeDesc parent;
public ExprNodeDesc grandParent;
public ReduceSinkOperator generator;
public DynamicListContext(ExprNodeDynamicListDesc desc, ExprNodeDesc parent,
ExprNodeDesc grandParent, ReduceSinkOperator generator) {
this.desc = desc;
this.parent = parent;
this.grandParent = grandParent;
this.generator = generator;
}
}
private static class DynamicPartitionPrunerContext implements NodeProcessorCtx,
Iterable {
public List dynLists = new ArrayList();
public void addDynamicList(ExprNodeDynamicListDesc desc, ExprNodeDesc parent,
ExprNodeDesc grandParent, ReduceSinkOperator generator) {
dynLists.add(new DynamicListContext(desc, parent, grandParent, generator));
}
@Override
public Iterator iterator() {
return dynLists.iterator();
}
}
private String extractColName(ExprNodeDesc root) {
if (root instanceof ExprNodeColumnDesc) {
return ((ExprNodeColumnDesc) root).getColumn();
} else {
if (root.getChildren() == null) {
return null;
}
String column = null;
for (ExprNodeDesc d: root.getChildren()) {
String candidate = extractColName(d);
if (column != null && candidate != null) {
return null;
} else if (candidate != null) {
column = candidate;
}
}
return column;
}
}
@Override
public Object process(Node nd, Stack stack, NodeProcessorCtx procCtx, Object... nodeOutputs)
throws SemanticException {
OptimizeTezProcContext context = (OptimizeTezProcContext) procCtx;
ParseContext parseContext = context.parseContext;
FilterOperator filter = (FilterOperator) nd;
FilterDesc desc = filter.getConf();
TableScanOperator ts = null;
if (!parseContext.getConf().getBoolVar(ConfVars.TEZ_DYNAMIC_PARTITION_PRUNING)) {
// nothing to do when the optimization is off
return null;
}
DynamicPartitionPrunerContext removerContext = new DynamicPartitionPrunerContext();
if (filter.getParentOperators().size() == 1
&& filter.getParentOperators().get(0) instanceof TableScanOperator) {
ts = (TableScanOperator) filter.getParentOperators().get(0);
}
if (LOG.isDebugEnabled()) {
LOG.debug("Parent: " + filter.getParentOperators().get(0));
LOG.debug("Filter: " + desc.getPredicateString());
LOG.debug("TableScan: " + ts);
}
// collect the dynamic pruning conditions
removerContext.dynLists.clear();
walkExprTree(desc.getPredicate(), removerContext);
for (DynamicListContext ctx : removerContext) {
String column = extractColName(ctx.parent);
if (ts != null && column != null) {
Table table = ts.getConf().getTableMetadata();
if (table != null && table.isPartitionKey(column)) {
String alias = ts.getConf().getAlias();
PrunedPartitionList plist = parseContext.getPrunedPartitions(alias, ts);
if (LOG.isDebugEnabled()) {
LOG.debug("alias: " + alias);
LOG.debug("pruned partition list: ");
if (plist != null) {
for (Partition p : plist.getPartitions()) {
LOG.debug(p.getCompleteName());
}
}
}
if (plist == null || plist.getPartitions().size() != 0) {
LOG.info("Dynamic partitioning: " + table.getCompleteName() + "." + column);
generateEventOperatorPlan(ctx, parseContext, ts, column);
} else {
// all partitions have been statically removed
LOG.debug("No partition pruning necessary.");
}
} else {
LOG.debug("Column " + column + " is not a partition column");
}
}
// we always remove the condition by replacing it with "true"
ExprNodeDesc constNode = new ExprNodeConstantDesc(ctx.parent.getTypeInfo(), true);
if (ctx.grandParent == null) {
desc.setPredicate(constNode);
} else {
int i = ctx.grandParent.getChildren().indexOf(ctx.parent);
ctx.grandParent.getChildren().remove(i);
ctx.grandParent.getChildren().add(i, constNode);
}
}
// if we pushed the predicate into the table scan we need to remove the
// synthetic conditions there.
cleanTableScanFilters(ts);
return false;
}
private void cleanTableScanFilters(TableScanOperator ts) throws SemanticException {
if (ts == null || ts.getConf() == null || ts.getConf().getFilterExpr() == null) {
// nothing to do
return;
}
DynamicPartitionPrunerContext removerContext = new DynamicPartitionPrunerContext();
// collect the dynamic pruning conditions
removerContext.dynLists.clear();
walkExprTree(ts.getConf().getFilterExpr(), removerContext);
for (DynamicListContext ctx : removerContext) {
// remove the condition by replacing it with "true"
ExprNodeDesc constNode = new ExprNodeConstantDesc(ctx.parent.getTypeInfo(), true);
if (ctx.grandParent == null) {
// we're the only node, just clear out the expression
ts.getConf().setFilterExpr(null);
} else {
int i = ctx.grandParent.getChildren().indexOf(ctx.parent);
ctx.grandParent.getChildren().remove(i);
ctx.grandParent.getChildren().add(i, constNode);
}
}
}
private void generateEventOperatorPlan(DynamicListContext ctx, ParseContext parseContext,
TableScanOperator ts, String column) {
// we will put a fork in the plan at the source of the reduce sink
Operator parentOfRS = ctx.generator.getParentOperators().get(0);
// we need the expr that generated the key of the reduce sink
ExprNodeDesc key = ctx.generator.getConf().getKeyCols().get(ctx.desc.getKeyIndex());
// we also need the expr for the partitioned table
ExprNodeDesc partKey = ctx.parent.getChildren().get(0);
if (LOG.isDebugEnabled()) {
LOG.debug("key expr: " + key);
LOG.debug("partition key expr: " + partKey);
}
List keyExprs = new ArrayList();
keyExprs.add(key);
// group by requires "ArrayList", don't ask.
ArrayList outputNames = new ArrayList();
outputNames.add(HiveConf.getColumnInternalName(0));
// project the relevant key column
SelectDesc select = new SelectDesc(keyExprs, outputNames);
SelectOperator selectOp =
(SelectOperator) OperatorFactory.getAndMakeChild(select, parentOfRS);
// do a group by on the list to dedup
float groupByMemoryUsage =
HiveConf.getFloatVar(parseContext.getConf(), HiveConf.ConfVars.HIVEMAPAGGRHASHMEMORY);
float memoryThreshold =
HiveConf.getFloatVar(parseContext.getConf(),
HiveConf.ConfVars.HIVEMAPAGGRMEMORYTHRESHOLD);
ArrayList groupByExprs = new ArrayList();
ExprNodeDesc groupByExpr =
new ExprNodeColumnDesc(key.getTypeInfo(), outputNames.get(0), null, false);
groupByExprs.add(groupByExpr);
GroupByDesc groupBy =
new GroupByDesc(GroupByDesc.Mode.HASH, outputNames, groupByExprs,
new ArrayList(), false, groupByMemoryUsage, memoryThreshold,
null, false, 0, true);
GroupByOperator groupByOp =
(GroupByOperator) OperatorFactory.getAndMakeChild(groupBy, selectOp);
Map colMap = new HashMap();
colMap.put(outputNames.get(0), groupByExpr);
groupByOp.setColumnExprMap(colMap);
// finally add the event broadcast operator
DynamicPruningEventDesc eventDesc = new DynamicPruningEventDesc();
eventDesc.setTableScan(ts);
eventDesc.setTable(PlanUtils.getReduceValueTableDesc(PlanUtils
.getFieldSchemasFromColumnList(keyExprs, "key")));
eventDesc.setTargetColumnName(column);
eventDesc.setPartKey(partKey);
OperatorFactory.getAndMakeChild(eventDesc, groupByOp);
}
private Map walkExprTree(ExprNodeDesc pred, NodeProcessorCtx ctx)
throws SemanticException {
// create a walker which walks the tree in a DFS manner while maintaining
// the operator stack. The dispatcher
// generates the plan from the operator tree
Map exprRules = new LinkedHashMap();
exprRules.put(new RuleRegExp("R1", ExprNodeDynamicListDesc.class.getName() + "%"),
new DynamicPartitionPrunerProc());
// The dispatcher fires the processor corresponding to the closest matching
// rule and passes the context along
Dispatcher disp = new DefaultRuleDispatcher(null, exprRules, ctx);
GraphWalker egw = new DefaultGraphWalker(disp);
List startNodes = new ArrayList();
startNodes.add(pred);
HashMap outputMap = new HashMap();
egw.startWalking(startNodes, outputMap);
return outputMap;
}
}
