/**
* 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.parse;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.ColumnInfo;
import org.apache.hadoop.hive.ql.exec.RowSchema;
/**
* Implementation of the Row Resolver.
*
*/
public class RowResolver implements Serializable{
private static final long serialVersionUID = 1L;
private RowSchema rowSchema;
private HashMap<String, LinkedHashMap<String, ColumnInfo>> rslvMap;
private HashMap<String, String[]> invRslvMap;
/*
* now a Column can have an alternate mapping.
* This captures the alternate mapping.
* The primary(first) mapping is still only held in
* invRslvMap.
*/
private final Map<String, String[]> altInvRslvMap;
private Map<String, ASTNode> expressionMap;
// TODO: Refactor this and do in a more object oriented manner
private boolean isExprResolver;
@SuppressWarnings("unused")
private static final Log LOG = LogFactory.getLog(RowResolver.class.getName());
public RowResolver() {
rowSchema = new RowSchema();
rslvMap = new HashMap<String, LinkedHashMap<String, ColumnInfo>>();
invRslvMap = new HashMap<String, String[]>();
altInvRslvMap = new HashMap<String, String[]>();
expressionMap = new HashMap<String, ASTNode>();
isExprResolver = false;
}
/**
* Puts a resolver entry corresponding to a source expression which is to be
* used for identical expression recognition (e.g. for matching expressions
* in the SELECT list with the GROUP BY clause). The convention for such
* entries is an empty-string ("") as the table alias together with the
* string rendering of the ASTNode as the column alias.
*/
public void putExpression(ASTNode node, ColumnInfo colInfo) {
String treeAsString = node.toStringTree();
expressionMap.put(treeAsString, node);
put("", treeAsString, colInfo);
}
/**
* Retrieves the ColumnInfo corresponding to a source expression which
* exactly matches the string rendering of the given ASTNode.
*/
public ColumnInfo getExpression(ASTNode node) throws SemanticException {
return get("", node.toStringTree());
}
/**
* Retrieves the source expression matching a given ASTNode's
* string rendering exactly.
*/
public ASTNode getExpressionSource(ASTNode node) {
return expressionMap.get(node.toStringTree());
}
public void put(String tab_alias, String col_alias, ColumnInfo colInfo) {
if (!addMappingOnly(tab_alias, col_alias, colInfo)) {
rowSchema.getSignature().add(colInfo);
}
}
public boolean addMappingOnly(String tab_alias, String col_alias, ColumnInfo colInfo) {
if (tab_alias != null) {
tab_alias = tab_alias.toLowerCase();
}
col_alias = col_alias.toLowerCase();
/*
* allow multiple mappings to the same ColumnInfo.
* When a ColumnInfo is mapped multiple times, only the
* first inverse mapping is captured.
*/
boolean colPresent = invRslvMap.containsKey(colInfo.getInternalName());
LinkedHashMap<String, ColumnInfo> f_map = rslvMap.get(tab_alias);
if (f_map == null) {
f_map = new LinkedHashMap<String, ColumnInfo>();
rslvMap.put(tab_alias, f_map);
}
ColumnInfo oldColInfo = f_map.put(col_alias, colInfo);
if (oldColInfo != null) {
LOG.warn("Duplicate column info for " + tab_alias + "." + col_alias
+ " was overwritten in RowResolver map: " + oldColInfo + " by " + colInfo);
}
String[] qualifiedAlias = new String[2];
qualifiedAlias[0] = tab_alias;
qualifiedAlias[1] = col_alias;
if ( !colPresent ) {
invRslvMap.put(colInfo.getInternalName(), qualifiedAlias);
} else {
altInvRslvMap.put(colInfo.getInternalName(), qualifiedAlias);
}
return colPresent;
}
public boolean hasTableAlias(String tab_alias) {
return rslvMap.get(tab_alias.toLowerCase()) != null;
}
/**
* Gets the column Info to tab_alias.col_alias type of a column reference. I
* the tab_alias is not provided as can be the case with an non aliased
* column, this function looks up the column in all the table aliases in this
* row resolver and returns the match. It also throws an exception if the
* column is found in multiple table aliases. If no match is found a null
* values is returned.
*
* This allows us to interpret both select t.c1 type of references and select
* c1 kind of references. The later kind are what we call non aliased column
* references in the query.
*
* @param tab_alias
* The table alias to match (this is null if the column reference is
* non aliased)
* @param col_alias
* The column name that is being searched for
* @return ColumnInfo
* @throws SemanticException
*/
public ColumnInfo get(String tab_alias, String col_alias) throws SemanticException {
col_alias = col_alias.toLowerCase();
ColumnInfo ret = null;
if (tab_alias != null) {
tab_alias = tab_alias.toLowerCase();
HashMap<String, ColumnInfo> f_map = rslvMap.get(tab_alias);
if (f_map == null) {
return null;
}
ret = f_map.get(col_alias);
} else {
boolean found = false;
String foundTbl = null;
for (Map.Entry<String, LinkedHashMap<String, ColumnInfo>> rslvEntry: rslvMap.entrySet()) {
String rslvKey = rslvEntry.getKey();
LinkedHashMap<String, ColumnInfo> cmap = rslvEntry.getValue();
for (Map.Entry<String, ColumnInfo> cmapEnt : cmap.entrySet()) {
if (col_alias.equalsIgnoreCase(cmapEnt.getKey())) {
/*
* We can have an unaliased and one aliased mapping to a Column.
*/
if (found && foundTbl != null && rslvKey != null) {
throw new SemanticException("Column " + col_alias
+ " Found in more than One Tables/Subqueries");
}
found = true;
foundTbl = rslvKey == null ? foundTbl : rslvKey;
ret = cmapEnt.getValue();
}
}
}
}
return ret;
}
public ArrayList<ColumnInfo> getColumnInfos() {
return rowSchema.getSignature();
}
/**
* Get a list of aliases for non-hidden columns
* @param max the maximum number of columns to return
* @return a list of non-hidden column names no greater in size than max
*/
public List<String> getReferenceableColumnAliases(String tableAlias, int max) {
int count = 0;
Set<String> columnNames = new LinkedHashSet<String> ();
int tables = rslvMap.size();
Map<String, ColumnInfo> mapping = rslvMap.get(tableAlias);
if (mapping != null) {
for (Map.Entry<String, ColumnInfo> entry : mapping.entrySet()) {
if (max > 0 && count >= max) {
break;
}
ColumnInfo columnInfo = entry.getValue();
if (!columnInfo.isHiddenVirtualCol()) {
columnNames.add(entry.getKey());
count++;
}
}
} else {
for (ColumnInfo columnInfo : getColumnInfos()) {
if (max > 0 && count >= max) {
break;
}
if (!columnInfo.isHiddenVirtualCol()) {
String[] inverse = !isExprResolver ? reverseLookup(columnInfo.getInternalName()) : null;
if (inverse != null) {
columnNames.add(inverse[0] == null || tables <= 1 ? inverse[1] :
inverse[0] + "." + inverse[1]);
} else {
columnNames.add(columnInfo.getAlias());
}
count++;
}
}
}
return new ArrayList<String>(columnNames);
}
public HashMap<String, ColumnInfo> getFieldMap(String tabAlias) {
if (tabAlias == null) {
return rslvMap.get(null);
} else {
return rslvMap.get(tabAlias.toLowerCase());
}
}
public int getPosition(String internalName) {
int pos = -1;
for (ColumnInfo var : rowSchema.getSignature()) {
++pos;
if (var.getInternalName().equals(internalName)) {
return pos;
}
}
return -1;
}
public Set<String> getTableNames() {
return rslvMap.keySet();
}
public String[] reverseLookup(String internalName) {
return invRslvMap.get(internalName);
}
public void setIsExprResolver(boolean isExprResolver) {
this.isExprResolver = isExprResolver;
}
public boolean getIsExprResolver() {
return isExprResolver;
}
public String[] getAlternateMappings(String internalName) {
return altInvRslvMap.get(internalName);
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (Map.Entry<String, LinkedHashMap<String, ColumnInfo>> e : rslvMap
.entrySet()) {
String tab = e.getKey();
sb.append(tab + "{");
HashMap<String, ColumnInfo> f_map = e.getValue();
if (f_map != null) {
for (Map.Entry<String, ColumnInfo> entry : f_map.entrySet()) {
sb.append("(" + entry.getKey() + "," + entry.getValue().toString()
+ ")");
}
}
sb.append("} ");
}
return sb.toString();
}
public RowSchema getRowSchema() {
return rowSchema;
}
public HashMap<String, LinkedHashMap<String, ColumnInfo>> getRslvMap() {
return rslvMap;
}
public HashMap<String, String[]> getInvRslvMap() {
return invRslvMap;
}
public Map<String, ASTNode> getExpressionMap() {
return expressionMap;
}
public void setExprResolver(boolean isExprResolver) {
this.isExprResolver = isExprResolver;
}
public void setRowSchema(RowSchema rowSchema) {
this.rowSchema = rowSchema;
}
public void setRslvMap(HashMap<String, LinkedHashMap<String, ColumnInfo>> rslvMap) {
this.rslvMap = rslvMap;
}
public void setInvRslvMap(HashMap<String, String[]> invRslvMap) {
this.invRslvMap = invRslvMap;
}
public void setExpressionMap(Map<String, ASTNode> expressionMap) {
this.expressionMap = expressionMap;
}
private static class IntRef {
public int val = 0;
}
public static boolean add(RowResolver rrToAddTo, RowResolver rrToAddFrom, int numColumns)
throws SemanticException {
return add(rrToAddTo, rrToAddFrom, null, numColumns);
}
// TODO: 1) How to handle collisions? 2) Should we be cloning ColumnInfo or not?
private static boolean add(RowResolver rrToAddTo, RowResolver rrToAddFrom,
IntRef outputColPosRef, int numColumns) throws SemanticException {
boolean hasDuplicates = false;
String tabAlias;
String colAlias;
String[] qualifiedColName;
int i = 0;
int outputColPos = outputColPosRef == null ? 0 : outputColPosRef.val;
for (ColumnInfo cInfoFrmInput : rrToAddFrom.getRowSchema().getSignature()) {
if ( numColumns >= 0 && i == numColumns ) {
break;
}
ColumnInfo newCI = null;
String internalName = cInfoFrmInput.getInternalName();
qualifiedColName = rrToAddFrom.reverseLookup(internalName);
tabAlias = qualifiedColName[0];
colAlias = qualifiedColName[1];
newCI = new ColumnInfo(cInfoFrmInput);
newCI.setInternalName(SemanticAnalyzer.getColumnInternalName(outputColPos));
outputColPos++;
boolean isUnique = rrToAddTo.putWithCheck(tabAlias, colAlias, internalName, newCI);
hasDuplicates |= (!isUnique);
qualifiedColName = rrToAddFrom.getAlternateMappings(internalName);
if (qualifiedColName != null) {
tabAlias = qualifiedColName[0];
colAlias = qualifiedColName[1];
rrToAddTo.put(tabAlias, colAlias, newCI);
}
i++;
}
if (outputColPosRef != null) {
outputColPosRef.val = outputColPos;
}
return !hasDuplicates;
}
/**
* Adds column to RR, checking for duplicate columns. Needed because CBO cannot handle the Hive
* behavior of blindly overwriting old mapping in RR and still somehow working after that.
* @return True if mapping was added without duplicates.
*/
public boolean putWithCheck(String tabAlias, String colAlias,
String internalName, ColumnInfo newCI) throws SemanticException {
ColumnInfo existing = get(tabAlias, colAlias);
// Hive adds the same mapping twice... I wish we could fix stuff like that.
if (existing == null) {
put(tabAlias, colAlias, newCI);
return true;
} else if (existing.isSameColumnForRR(newCI)) {
return true;
}
LOG.warn("Found duplicate column alias in RR: "
+ existing.toMappingString(tabAlias, colAlias) + " adding "
+ newCI.toMappingString(tabAlias, colAlias));
if (internalName != null) {
existing = get(tabAlias, internalName);
if (existing == null) {
put(tabAlias, internalName, newCI);
return true;
} else if (existing.isSameColumnForRR(newCI)) {
return true;
}
LOG.warn("Failed to use internal name after finding a duplicate: "
+ existing.toMappingString(tabAlias, internalName));
}
return false;
}
private static boolean add(RowResolver rrToAddTo, RowResolver rrToAddFrom,
IntRef outputColPosRef) throws SemanticException {
return add(rrToAddTo, rrToAddFrom, outputColPosRef, -1);
}
public static boolean add(RowResolver rrToAddTo, RowResolver rrToAddFrom)
throws SemanticException {
return add(rrToAddTo, rrToAddFrom, null, -1);
}
/**
* Return a new row resolver that is combination of left RR and right RR.
* The schema will be schema of left, schema of right
*
* @param leftRR
* @param rightRR
* @return
* @throws SemanticException
*/
public static RowResolver getCombinedRR(RowResolver leftRR,
RowResolver rightRR) throws SemanticException {
RowResolver combinedRR = new RowResolver();
IntRef outputColPos = new IntRef();
if (!add(combinedRR, leftRR, outputColPos)) {
LOG.warn("Duplicates detected when adding columns to RR: see previous message");
}
if (!add(combinedRR, rightRR, outputColPos)) {
LOG.warn("Duplicates detected when adding columns to RR: see previous message");
}
return combinedRR;
}
}