/*
* Copyright 2014-2015 the original author or authors
*
* Licensed 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 com.wplatform.ddal.command.expression;
import java.util.List;
import com.wplatform.ddal.command.dml.Query;
import com.wplatform.ddal.dbobject.index.IndexCondition;
import com.wplatform.ddal.dbobject.table.ColumnResolver;
import com.wplatform.ddal.dbobject.table.TableFilter;
import com.wplatform.ddal.engine.Database;
import com.wplatform.ddal.engine.Session;
import com.wplatform.ddal.message.DbException;
import com.wplatform.ddal.message.ErrorCode;
import com.wplatform.ddal.result.LocalResult;
import com.wplatform.ddal.util.StatementBuilder;
import com.wplatform.ddal.util.StringUtils;
import com.wplatform.ddal.value.Value;
import com.wplatform.ddal.value.ValueBoolean;
import com.wplatform.ddal.value.ValueNull;
/**
* An 'in' condition with a subquery, as in WHERE ID IN(SELECT ...)
*/
public class ConditionInSelect extends Condition {
private final Database database;
private final Query query;
private final boolean all;
private final int compareType;
private Expression left;
private int queryLevel;
private LocalResult cachedResult;
public ConditionInSelect(Database database, Expression left, Query query,
boolean all, int compareType) {
this.database = database;
this.left = left;
this.query = query;
this.all = all;
this.compareType = compareType;
}
@Override
public Value getValue(Session session) {
LocalResult rows = query(session);
try {
Value l = left.getValue(session);
if (rows.getRowCount() == 0) {
return ValueBoolean.get(all);
} else if (l == ValueNull.INSTANCE) {
return l;
}
if (!session.getDatabase().getSettings().optimizeInSelect) {
return getValueSlow(rows, l);
}
if (all || (compareType != Comparison.EQUAL &&
compareType != Comparison.EQUAL_NULL_SAFE)) {
return getValueSlow(rows, l);
}
int dataType = rows.getColumnType(0);
if (dataType == Value.NULL) {
return ValueBoolean.get(false);
}
l = l.convertTo(dataType);
if (rows.containsDistinct(new Value[]{l})) {
return ValueBoolean.get(true);
}
if (rows.containsDistinct(new Value[]{ValueNull.INSTANCE})) {
return ValueNull.INSTANCE;
}
return ValueBoolean.get(false);
} finally {
rows.close();
}
}
private Value getValueSlow(LocalResult rows, Value l) {
// this only returns the correct result if the result has at least one
// row, and if l is not null
boolean hasNull = false;
boolean result = all;
while (rows.next()) {
boolean value;
Value r = rows.currentRow()[0];
if (r == ValueNull.INSTANCE) {
value = false;
hasNull = true;
} else {
value = Comparison.compareNotNull(database, l, r, compareType);
}
if (!value && all) {
result = false;
break;
} else if (value && !all) {
result = true;
break;
}
}
if (!result && hasNull) {
return ValueNull.INSTANCE;
}
return ValueBoolean.get(result);
}
@Override
public void mapColumns(ColumnResolver resolver, int level) {
left.mapColumns(resolver, level);
query.mapColumns(resolver, level + 1);
this.queryLevel = Math.max(level, this.queryLevel);
}
@Override
public Expression optimize(Session session) {
left = left.optimize(session);
query.setRandomAccessResult(true);
query.prepare();
if (query.getColumnCount() != 1) {
throw DbException.get(ErrorCode.SUBQUERY_IS_NOT_SINGLE_COLUMN);
}
// Can not optimize: the data may change
return this;
}
@Override
public void setEvaluatable(TableFilter tableFilter, boolean b) {
left.setEvaluatable(tableFilter, b);
query.setEvaluatable(tableFilter, b);
}
@Override
public String getSQL() {
StringBuilder buff = new StringBuilder();
buff.append('(').append(left.getSQL()).append(' ');
if (all) {
buff.append(Comparison.getCompareOperator(compareType)).
append(" ALL");
} else {
if (compareType == Comparison.EQUAL) {
buff.append("IN");
} else {
buff.append(Comparison.getCompareOperator(compareType)).
append(" ANY");
}
}
buff.append("(\n").append(StringUtils.indent(query.getPlanSQL(), 4, false)).
append("))");
return buff.toString();
}
@Override
public void updateAggregate(Session session) {
left.updateAggregate(session);
query.updateAggregate(session);
}
@Override
public boolean isEverything(ExpressionVisitor visitor) {
return left.isEverything(visitor) && query.isEverything(visitor);
}
@Override
public int getCost() {
return left.getCost() + query.getCostAsExpression();
}
@Override
public void createIndexConditions(Session session, TableFilter filter) {
if (!session.getDatabase().getSettings().optimizeInList) {
return;
}
if (!(left instanceof ExpressionColumn)) {
return;
}
ExpressionColumn l = (ExpressionColumn) left;
if (filter != l.getTableFilter()) {
return;
}
ExpressionVisitor visitor = ExpressionVisitor.getNotFromResolverVisitor(filter);
if (!query.isEverything(visitor)) {
return;
}
filter.addIndexCondition(IndexCondition.getInQuery(l, query));
}
@Override
public String exportParameters(TableFilter filter, List<Value> container) {
Session session = filter.getSession();
LocalResult rows = query(session);
if (rows.getRowCount() > 0) {
StatementBuilder buff = new StatementBuilder();
buff.append('(').append(left.exportParameters(filter, container)).append(' ');
if (all) {
//由于all代表全部，所以<all表示小于子查询中返回全部值中的最小值；
//>all表示大于子查询中返回全部值中的最大值。
buff.append(Comparison.getCompareOperator(compareType)).
append(" ALL");
} else {
if (compareType == Comparison.EQUAL) {
buff.append("IN");
} else {
//<any可以理解为小于子查询中返回的任意一个值，因此只要小于最大值即可
//>any可以理解为大于子查询中返回的任意一个值，因此只要大于最小值即可
buff.append(Comparison.getCompareOperator(compareType)).
append(" ANY");
}
}
buff.append("(");
while (rows.next()) {
buff.appendExceptFirst(",");
buff.append("?");
Value r = rows.currentRow()[0];
container.add(r);
}
buff.append("))");
return buff.toString();
} else {
return "1 = 0";
}
}
private LocalResult query(Session session) {
if (cachedResult == null) {
query.setSession(session);
query.setDistinct(true);
cachedResult = query.query(0);
} else {
cachedResult.reset();
}
return cachedResult;
}
}