/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.command.dml;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import org.h2.api.Trigger;
import org.h2.command.CommandInterface;
import org.h2.constant.ErrorCode;
import org.h2.constant.SysProperties;
import org.h2.engine.Constants;
import org.h2.engine.Database;
import org.h2.engine.Session;
import org.h2.expression.Comparison;
import org.h2.expression.ConditionAndOr;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionColumn;
import org.h2.expression.ExpressionVisitor;
import org.h2.expression.Parameter;
import org.h2.expression.Wildcard;
import org.h2.index.Cursor;
import org.h2.index.Index;
import org.h2.index.IndexType;
import org.h2.message.DbException;
import org.h2.result.LocalResult;
import org.h2.result.ResultInterface;
import org.h2.result.ResultTarget;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.result.SortOrder;
import org.h2.table.Column;
import org.h2.table.ColumnResolver;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.table.TableFilter;
import org.h2.util.New;
import org.h2.util.StatementBuilder;
import org.h2.util.StringUtils;
import org.h2.util.ValueHashMap;
import org.h2.value.Value;
import org.h2.value.ValueArray;
import org.h2.value.ValueNull;
/**
* This class represents a simple SELECT statement.
*
* For each select statement,
* visibleColumnCount <= distinctColumnCount <= expressionCount.
* The expression list count could include ORDER BY and GROUP BY expressions
* that are not in the select list.
*
* The call sequence is init(), mapColumns() if it's a subquery, prepare().
*
* @author Thomas Mueller
* @author Joel Turkel (Group sorted query)
*/
public class Select extends Query {
private TableFilter topTableFilter;
private ArrayList<TableFilter> filters = New.arrayList();
private ArrayList<TableFilter> topFilters = New.arrayList();
private ArrayList<Expression> expressions;
private Expression[] expressionArray;
private Expression having;
private Expression condition;
private int visibleColumnCount, distinctColumnCount;
private ArrayList<SelectOrderBy> orderList;
private ArrayList<Expression> group;
private int[] groupIndex;
private boolean[] groupByExpression;
private HashMap<Expression, Object> currentGroup;
private int havingIndex;
private boolean isGroupQuery, isGroupSortedQuery;
private boolean isForUpdate, isForUpdateMvcc;
private double cost;
private boolean isQuickAggregateQuery, isDistinctQuery;
private boolean isPrepared, checkInit;
private boolean sortUsingIndex;
private SortOrder sort;
private int currentGroupRowId;
public Select(Session session) {
super(session);
}
/**
* Add a table to the query.
*
* @param filter the table to add
* @param isTop if the table can be the first table in the query plan
*/
public void addTableFilter(TableFilter filter, boolean isTop) {
// Oracle doesn't check on duplicate aliases
// String alias = filter.getAlias();
// if(filterNames.contains(alias)) {
// throw Message.getSQLException(
// ErrorCode.DUPLICATE_TABLE_ALIAS, alias);
// }
// filterNames.add(alias);
filters.add(filter);
if (isTop) {
topFilters.add(filter);
}
}
public ArrayList<TableFilter> getTopFilters() {
return topFilters;
}
public void setExpressions(ArrayList<Expression> expressions) {
this.expressions = expressions;
}
/**
* Called if this query contains aggregate functions.
*/
public void setGroupQuery() {
isGroupQuery = true;
}
public void setGroupBy(ArrayList<Expression> group) {
this.group = group;
}
public HashMap<Expression, Object> getCurrentGroup() {
return currentGroup;
}
public int getCurrentGroupRowId() {
return currentGroupRowId;
}
public void setOrder(ArrayList<SelectOrderBy> order) {
orderList = order;
}
/**
* Add a condition to the list of conditions.
*
* @param cond the condition to add
*/
public void addCondition(Expression cond) {
if (condition == null) {
condition = cond;
} else {
condition = new ConditionAndOr(ConditionAndOr.AND, cond, condition);
}
}
private void queryGroupSorted(int columnCount, ResultTarget result) {
int rowNumber = 0;
setCurrentRowNumber(0);
Value[] previousKeyValues = null;
while (topTableFilter.next()) {
setCurrentRowNumber(rowNumber + 1);
if (condition == null || Boolean.TRUE.equals(condition.getBooleanValue(session))) {
rowNumber++;
Value[] keyValues = new Value[groupIndex.length];
// update group
for (int i = 0; i < groupIndex.length; i++) {
int idx = groupIndex[i];
Expression expr = expressions.get(idx);
keyValues[i] = expr.getValue(session);
}
if (previousKeyValues == null) {
previousKeyValues = keyValues;
currentGroup = New.hashMap();
} else if (!Arrays.equals(previousKeyValues, keyValues)) {
addGroupSortedRow(previousKeyValues, columnCount, result);
previousKeyValues = keyValues;
currentGroup = New.hashMap();
}
currentGroupRowId++;
for (int i = 0; i < columnCount; i++) {
if (groupByExpression == null || !groupByExpression[i]) {
Expression expr = expressions.get(i);
expr.updateAggregate(session);
}
}
}
}
if (previousKeyValues != null) {
addGroupSortedRow(previousKeyValues, columnCount, result);
}
}
private void addGroupSortedRow(Value[] keyValues, int columnCount, ResultTarget result) {
Value[] row = new Value[columnCount];
for (int j = 0; groupIndex != null && j < groupIndex.length; j++) {
row[groupIndex[j]] = keyValues[j];
}
for (int j = 0; j < columnCount; j++) {
if (groupByExpression != null && groupByExpression[j]) {
continue;
}
Expression expr = expressions.get(j);
row[j] = expr.getValue(session);
}
if (isHavingNullOrFalse(row)) {
return;
}
row = keepOnlyDistinct(row, columnCount);
result.addRow(row);
}
private Value[] keepOnlyDistinct(Value[] row, int columnCount) {
if (columnCount == distinctColumnCount) {
return row;
}
// remove columns so that 'distinct' can filter duplicate rows
Value[] r2 = new Value[distinctColumnCount];
System.arraycopy(row, 0, r2, 0, distinctColumnCount);
return r2;
}
private boolean isHavingNullOrFalse(Value[] row) {
if (havingIndex >= 0) {
Value v = row[havingIndex];
if (v == ValueNull.INSTANCE) {
return true;
}
if (!Boolean.TRUE.equals(v.getBoolean())) {
return true;
}
}
return false;
}
private Index getGroupSortedIndex() {
if (groupIndex == null || groupByExpression == null) {
return null;
}
ArrayList<Index> indexes = topTableFilter.getTable().getIndexes();
if (indexes != null) {
for (int i = 0, size = indexes.size(); i < size; i++) {
Index index = indexes.get(i);
if (index.getIndexType().isScan()) {
continue;
}
if (isGroupSortedIndex(topTableFilter, index)) {
return index;
}
}
}
return null;
}
private boolean isGroupSortedIndex(TableFilter tableFilter, Index index) {
// check that all the GROUP BY expressions are part of the index
Column[] indexColumns = index.getColumns();
// also check that the first columns in the index are grouped
boolean[] grouped = new boolean[indexColumns.length];
outerLoop:
for (int i = 0, size = expressions.size(); i < size; i++) {
if (!groupByExpression[i]) {
continue;
}
Expression expr = expressions.get(i).getNonAliasExpression();
if (!(expr instanceof ExpressionColumn)) {
return false;
}
ExpressionColumn exprCol = (ExpressionColumn) expr;
for (int j = 0; j < indexColumns.length; ++j) {
if (tableFilter == exprCol.getTableFilter()) {
if (indexColumns[j].equals(exprCol.getColumn())) {
grouped[j] = true;
continue outerLoop;
}
}
}
// We didn't find a matching index column
// for one group by expression
return false;
}
// check that the first columns in the index are grouped
// good: index(a, b, c); group by b, a
// bad: index(a, b, c); group by a, c
for (int i = 1; i < grouped.length; i++) {
if (!grouped[i - 1] && grouped[i]) {
return false;
}
}
return true;
}
private int getGroupByExpressionCount() {
if (groupByExpression == null) {
return 0;
}
int count = 0;
for (boolean b : groupByExpression) {
if (b) {
++count;
}
}
return count;
}
private void queryGroup(int columnCount, LocalResult result) {
ValueHashMap<HashMap<Expression, Object>> groups = ValueHashMap.newInstance();
int rowNumber = 0;
setCurrentRowNumber(0);
ValueArray defaultGroup = ValueArray.get(new Value[0]);
while (topTableFilter.next()) {
setCurrentRowNumber(rowNumber + 1);
if (condition == null || Boolean.TRUE.equals(condition.getBooleanValue(session))) {
Value key;
rowNumber++;
if (groupIndex == null) {
key = defaultGroup;
} else {
Value[] keyValues = new Value[groupIndex.length];
// update group
for (int i = 0; i < groupIndex.length; i++) {
int idx = groupIndex[i];
Expression expr = expressions.get(idx);
keyValues[i] = expr.getValue(session);
}
key = ValueArray.get(keyValues);
}
HashMap<Expression, Object> values = groups.get(key);
if (values == null) {
values = new HashMap<Expression, Object>();
groups.put(key, values);
}
currentGroup = values;
currentGroupRowId++;
int len = columnCount;
for (int i = 0; i < len; i++) {
if (groupByExpression == null || !groupByExpression[i]) {
Expression expr = expressions.get(i);
expr.updateAggregate(session);
}
}
if (sampleSize > 0 && rowNumber >= sampleSize) {
break;
}
}
}
if (groupIndex == null && groups.size() == 0) {
groups.put(defaultGroup, new HashMap<Expression, Object>());
}
ArrayList<Value> keys = groups.keys();
for (Value v : keys) {
ValueArray key = (ValueArray) v;
currentGroup = groups.get(key);
Value[] keyValues = key.getList();
Value[] row = new Value[columnCount];
for (int j = 0; groupIndex != null && j < groupIndex.length; j++) {
row[groupIndex[j]] = keyValues[j];
}
for (int j = 0; j < columnCount; j++) {
if (groupByExpression != null && groupByExpression[j]) {
continue;
}
Expression expr = expressions.get(j);
row[j] = expr.getValue(session);
}
if (isHavingNullOrFalse(row)) {
continue;
}
row = keepOnlyDistinct(row, columnCount);
result.addRow(row);
}
}
/**
* Get the index that matches the ORDER BY list, if one exists. This is to
* avoid running a separate ORDER BY if an index can be used. This is
* specially important for large result sets, if only the first few rows are
* important (LIMIT is used)
*
* @return the index if one is found
*/
private Index getSortIndex() {
if (sort == null) {
return null;
}
ArrayList<Column> sortColumns = New.arrayList();
for (int idx : sort.getIndexes()) {
if (idx < 0 || idx >= expressions.size()) {
throw DbException.getInvalidValueException("ORDER BY", idx + 1);
}
Expression expr = expressions.get(idx);
expr = expr.getNonAliasExpression();
if (expr.isConstant()) {
continue;
}
if (!(expr instanceof ExpressionColumn)) {
return null;
}
ExpressionColumn exprCol = (ExpressionColumn) expr;
if (exprCol.getTableFilter() != topTableFilter) {
return null;
}
sortColumns.add(exprCol.getColumn());
}
Column[] sortCols = sortColumns.toArray(new Column[sortColumns.size()]);
int[] sortTypes = sort.getSortTypes();
if (sortCols.length == 0) {
// sort just on constants - can use scan index
return topTableFilter.getTable().getScanIndex(session);
}
ArrayList<Index> list = topTableFilter.getTable().getIndexes();
if (list != null) {
for (int i = 0, size = list.size(); i < size; i++) {
Index index = list.get(i);
if (index.getCreateSQL() == null) {
// can't use the scan index
continue;
}
if (index.getIndexType().isHash()) {
continue;
}
IndexColumn[] indexCols = index.getIndexColumns();
if (indexCols.length < sortCols.length) {
continue;
}
boolean ok = true;
for (int j = 0; j < sortCols.length; j++) {
// the index and the sort order must start
// with the exact same columns
IndexColumn idxCol = indexCols[j];
Column sortCol = sortCols[j];
if (idxCol.column != sortCol) {
ok = false;
break;
}
if (idxCol.sortType != sortTypes[j]) {
// NULL FIRST for ascending and NULLS LAST
// for descending would actually match the default
ok = false;
break;
}
}
if (ok) {
return index;
}
}
}
if (sortCols.length == 1 && sortCols[0].getColumnId() == -1) {
// special case: order by _ROWID_
Index index = topTableFilter.getTable().getScanIndex(session);
if (index.isRowIdIndex()) {
return index;
}
}
return null;
}
private void queryDistinct(ResultTarget result, long limitRows) {
// limitRows must be long, otherwise we get an int overflow
// if limitRows is at or near Integer.MAX_VALUE
// limitRows is never 0 here
if (limitRows > 0 && offsetExpr != null) {
int offset = offsetExpr.getValue(session).getInt();
if (offset > 0) {
limitRows += offset;
}
}
int rowNumber = 0;
setCurrentRowNumber(0);
Index index = topTableFilter.getIndex();
SearchRow first = null;
int columnIndex = index.getColumns()[0].getColumnId();
while (true) {
setCurrentRowNumber(rowNumber + 1);
Cursor cursor = index.findNext(session, first, null);
if (!cursor.next()) {
break;
}
SearchRow found = cursor.getSearchRow();
Value value = found.getValue(columnIndex);
if (first == null) {
first = topTableFilter.getTable().getTemplateSimpleRow(true);
}
first.setValue(columnIndex, value);
Value[] row = { value };
result.addRow(row);
rowNumber++;
if ((sort == null || sortUsingIndex) && limitRows > 0 && rowNumber >= limitRows) {
break;
}
if (sampleSize > 0 && rowNumber >= sampleSize) {
break;
}
}
}
private void queryFlat(int columnCount, ResultTarget result, long limitRows) {
// limitRows must be long, otherwise we get an int overflow
// if limitRows is at or near Integer.MAX_VALUE
// limitRows is never 0 here
if (limitRows > 0 && offsetExpr != null) {
int offset = offsetExpr.getValue(session).getInt();
if (offset > 0) {
limitRows += offset;
}
}
int rowNumber = 0;
setCurrentRowNumber(0);
ArrayList<Row> forUpdateRows = null;
if (isForUpdateMvcc) {
forUpdateRows = New.arrayList();
}
while (topTableFilter.next()) {
setCurrentRowNumber(rowNumber + 1);
if (condition == null || Boolean.TRUE.equals(condition.getBooleanValue(session))) {
Value[] row = new Value[columnCount];
for (int i = 0; i < columnCount; i++) {
Expression expr = expressions.get(i);
row[i] = expr.getValue(session);
}
if (isForUpdateMvcc) {
topTableFilter.lockRowAdd(forUpdateRows);
}
result.addRow(row);
rowNumber++;
if ((sort == null || sortUsingIndex) && limitRows > 0 && result.getRowCount() >= limitRows) {
break;
}
if (sampleSize > 0 && rowNumber >= sampleSize) {
break;
}
}
}
if (isForUpdateMvcc) {
topTableFilter.lockRows(forUpdateRows);
}
}
private void queryQuick(int columnCount, ResultTarget result) {
Value[] row = new Value[columnCount];
for (int i = 0; i < columnCount; i++) {
Expression expr = expressions.get(i);
row[i] = expr.getValue(session);
}
result.addRow(row);
}
public ResultInterface queryMeta() {
LocalResult result = new LocalResult(session, expressionArray, visibleColumnCount);
result.done();
return result;
}
protected LocalResult queryWithoutCache(int maxRows, ResultTarget target) {
int limitRows = maxRows == 0 ? -1 : maxRows;
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
int l = v == ValueNull.INSTANCE ? -1 : v.getInt();
if (limitRows < 0) {
limitRows = l;
} else if (l >= 0) {
limitRows = Math.min(l, limitRows);
}
}
int columnCount = expressions.size();
LocalResult result = null;
if (target == null || !session.getDatabase().getSettings().optimizeInsertFromSelect) {
result = createLocalResult(result);
}
if (sort != null && (!sortUsingIndex || distinct)) {
result = createLocalResult(result);
result.setSortOrder(sort);
}
if (distinct && !isDistinctQuery) {
result = createLocalResult(result);
result.setDistinct();
}
if (randomAccessResult) {
result = createLocalResult(result);
result.setRandomAccess();
}
if (isGroupQuery && !isGroupSortedQuery) {
result = createLocalResult(result);
}
if (limitRows >= 0 || offsetExpr != null) {
result = createLocalResult(result);
}
topTableFilter.startQuery(session);
topTableFilter.reset();
boolean exclusive = isForUpdate && !isForUpdateMvcc;
if (isForUpdateMvcc) {
if (isGroupQuery) {
throw DbException.getUnsupportedException("FOR UPDATE && GROUP");
} else if (distinct) {
throw DbException.getUnsupportedException("FOR UPDATE && DISTINCT");
} else if (isQuickAggregateQuery) {
throw DbException.getUnsupportedException("FOR UPDATE && AGGREGATE");
} else if (topTableFilter.getJoin() != null) {
throw DbException.getUnsupportedException("FOR UPDATE && JOIN");
} else if (topTableFilter.getJoin() != null) {
throw DbException.getUnsupportedException("FOR UPDATE && JOIN");
}
}
topTableFilter.lock(session, exclusive, exclusive);
ResultTarget to = result != null ? result : target;
if (limitRows != 0) {
if (isQuickAggregateQuery) {
queryQuick(columnCount, to);
} else if (isGroupQuery) {
if (isGroupSortedQuery) {
queryGroupSorted(columnCount, to);
} else {
queryGroup(columnCount, result);
}
} else if (isDistinctQuery) {
queryDistinct(to, limitRows);
} else {
queryFlat(columnCount, to, limitRows);
}
}
if (offsetExpr != null) {
result.setOffset(offsetExpr.getValue(session).getInt());
}
if (limitRows >= 0) {
result.setLimit(limitRows);
}
if (result != null) {
result.done();
if (target != null) {
while (result.next()) {
target.addRow(result.currentRow());
}
result.close();
return null;
}
return result;
}
return null;
}
private LocalResult createLocalResult(LocalResult old) {
return old != null ? old : new LocalResult(session, expressionArray, visibleColumnCount);
}
private void expandColumnList() {
Database db = session.getDatabase();
// the expressions may change within the loop
for (int i = 0; i < expressions.size(); i++) {
Expression expr = expressions.get(i);
if (!expr.isWildcard()) {
continue;
}
String schemaName = expr.getSchemaName();
String tableAlias = expr.getTableAlias();
if (tableAlias == null) {
int temp = i;
expressions.remove(i);
for (TableFilter filter : filters) {
Wildcard c2 = new Wildcard(filter.getTable().getSchema().getName(), filter.getTableAlias());
expressions.add(i++, c2);
}
i = temp - 1;
} else {
TableFilter filter = null;
for (TableFilter f : filters) {
if (db.equalsIdentifiers(tableAlias, f.getTableAlias())) {
if (schemaName == null || db.equalsIdentifiers(schemaName, f.getSchemaName())) {
filter = f;
break;
}
}
}
if (filter == null) {
throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, tableAlias);
}
Table t = filter.getTable();
String alias = filter.getTableAlias();
expressions.remove(i);
Column[] columns = t.getColumns();
for (Column c : columns) {
if (filter.isNaturalJoinColumn(c)) {
continue;
}
ExpressionColumn ec = new ExpressionColumn(session.getDatabase(), null, alias, c.getName());
expressions.add(i++, ec);
}
i--;
}
}
}
public void init() {
if (SysProperties.CHECK && checkInit) {
DbException.throwInternalError();
}
expandColumnList();
visibleColumnCount = expressions.size();
ArrayList<String> expressionSQL;
if (orderList != null || group != null) {
expressionSQL = New.arrayList();
for (int i = 0; i < visibleColumnCount; i++) {
Expression expr = expressions.get(i);
expr = expr.getNonAliasExpression();
String sql = expr.getSQL();
expressionSQL.add(sql);
}
} else {
expressionSQL = null;
}
if (orderList != null) {
initOrder(session, expressions, expressionSQL, orderList, visibleColumnCount, distinct, filters);
}
distinctColumnCount = expressions.size();
if (having != null) {
expressions.add(having);
havingIndex = expressions.size() - 1;
having = null;
} else {
havingIndex = -1;
}
Database db = session.getDatabase();
// first the select list (visible columns),
// then 'ORDER BY' expressions,
// then 'HAVING' expressions,
// and 'GROUP BY' expressions at the end
if (group != null) {
int size = group.size();
int expSize = expressionSQL.size();
groupIndex = new int[size];
for (int i = 0; i < size; i++) {
Expression expr = group.get(i);
String sql = expr.getSQL();
int found = -1;
for (int j = 0; j < expSize; j++) {
String s2 = expressionSQL.get(j);
if (db.equalsIdentifiers(s2, sql)) {
found = j;
break;
}
}
if (found < 0) {
// special case: GROUP BY a column alias
for (int j = 0; j < expSize; j++) {
Expression e = expressions.get(j);
if (db.equalsIdentifiers(sql, e.getAlias())) {
found = j;
break;
}
}
}
if (found < 0) {
int index = expressions.size();
groupIndex[i] = index;
expressions.add(expr);
} else {
groupIndex[i] = found;
}
}
groupByExpression = new boolean[expressions.size()];
for (int gi : groupIndex) {
groupByExpression[gi] = true;
}
group = null;
}
// map columns in select list and condition
for (TableFilter f : filters) {
for (Expression expr : expressions) {
expr.mapColumns(f, 0);
}
if (condition != null) {
condition.mapColumns(f, 0);
}
}
if (havingIndex >= 0) {
Expression expr = expressions.get(havingIndex);
SelectListColumnResolver res = new SelectListColumnResolver(this);
expr.mapColumns(res, 0);
}
checkInit = true;
}
public void prepare() {
if (isPrepared) {
// sometimes a subquery is prepared twice (CREATE TABLE AS SELECT)
return;
}
if (SysProperties.CHECK && !checkInit) {
DbException.throwInternalError("not initialized");
}
if (orderList != null) {
sort = prepareOrder(orderList, expressions.size());
orderList = null;
}
for (int i = 0; i < expressions.size(); i++) {
Expression e = expressions.get(i);
expressions.set(i, e.optimize(session));
}
if (condition != null) {
condition = condition.optimize(session);
for (TableFilter f : filters) {
// outer joins: must not add index conditions such as
// "c is null" - example:
// create table parent(p int primary key) as select 1;
// create table child(c int primary key, pc int);
// insert into child values(2, 1);
// select p, c from parent
// left outer join child on p = pc where c is null;
if (!f.isJoinOuter() && !f.isJoinOuterIndirect()) {
condition.createIndexConditions(session, f);
}
}
}
if (isGroupQuery && groupIndex == null && havingIndex < 0 && filters.size() == 1) {
if (condition == null) {
Table t = filters.get(0).getTable();
ExpressionVisitor optimizable = ExpressionVisitor.getOptimizableVisitor(t);
isQuickAggregateQuery = isEverything(optimizable);
}
}
cost = preparePlan();
if (distinct && session.getDatabase().getSettings().optimizeDistinct &&
!isGroupQuery && filters.size() == 1 &&
expressions.size() == 1 && condition == null) {
Expression expr = expressions.get(0);
expr = expr.getNonAliasExpression();
if (expr instanceof ExpressionColumn) {
Column column = ((ExpressionColumn) expr).getColumn();
int selectivity = column.getSelectivity();
Index columnIndex = topTableFilter.getTable().getIndexForColumn(column, true);
if (columnIndex != null && selectivity != Constants.SELECTIVITY_DEFAULT && selectivity < 20) {
// the first column must be ascending
boolean ascending = columnIndex.getIndexColumns()[0].sortType == SortOrder.ASCENDING;
Index current = topTableFilter.getIndex();
// if another index is faster
if (columnIndex.canFindNext() && ascending &&
(current == null || current.getIndexType().isScan() || columnIndex == current)) {
IndexType type = columnIndex.getIndexType();
// hash indexes don't work, and unique single column indexes don't work
if (!type.isHash() && (!type.isUnique() || columnIndex.getColumns().length > 1)) {
topTableFilter.setIndex(columnIndex);
isDistinctQuery = true;
}
}
}
}
}
if (sort != null && !isQuickAggregateQuery && !isGroupQuery) {
Index index = getSortIndex();
if (index != null) {
Index current = topTableFilter.getIndex();
if (current.getIndexType().isScan() || current == index) {
topTableFilter.setIndex(index);
if (!topTableFilter.hasInComparisons()) {
// in(select ...) and in(1,2,3) my return the key in another order
sortUsingIndex = true;
}
} else if (index.getIndexColumns().length >= current.getIndexColumns().length) {
IndexColumn[] sortColumns = index.getIndexColumns();
IndexColumn[] currentColumns = current.getIndexColumns();
boolean swapIndex = false;
for (int i = 0; i < currentColumns.length; i++) {
if (sortColumns[i].column != currentColumns[i].column) {
swapIndex = false;
break;
}
if (sortColumns[i].sortType != currentColumns[i].sortType) {
swapIndex = true;
}
}
if (swapIndex) {
topTableFilter.setIndex(index);
sortUsingIndex = true;
}
}
}
}
if (!isQuickAggregateQuery && isGroupQuery && getGroupByExpressionCount() > 0) {
Index index = getGroupSortedIndex();
Index current = topTableFilter.getIndex();
if (index != null && (current.getIndexType().isScan() || current == index)) {
topTableFilter.setIndex(index);
isGroupSortedQuery = true;
}
}
expressionArray = new Expression[expressions.size()];
expressions.toArray(expressionArray);
isPrepared = true;
}
public double getCost() {
return cost;
}
public HashSet<Table> getTables() {
HashSet<Table> set = New.hashSet();
for (TableFilter filter : filters) {
set.add(filter.getTable());
}
return set;
}
public void fireBeforeSelectTriggers() {
for (int i = 0, size = filters.size(); i < size; i++) {
TableFilter filter = filters.get(i);
filter.getTable().fire(session, Trigger.SELECT, true);
}
}
private double preparePlan() {
TableFilter[] topArray = topFilters.toArray(new TableFilter[topFilters.size()]);
for (TableFilter t : topArray) {
t.setFullCondition(condition);
}
Optimizer optimizer = new Optimizer(topArray, condition, session);
optimizer.optimize();
topTableFilter = optimizer.getTopFilter();
double planCost = optimizer.getCost();
setEvaluatableRecursive(topTableFilter);
topTableFilter.prepare();
return planCost;
}
private void setEvaluatableRecursive(TableFilter f) {
for (; f != null; f = f.getJoin()) {
f.setEvaluatable(f, true);
if (condition != null) {
condition.setEvaluatable(f, true);
}
TableFilter n = f.getNestedJoin();
if (n != null) {
setEvaluatableRecursive(n);
}
Expression on = f.getJoinCondition();
if (on != null) {
if (!on.isEverything(ExpressionVisitor.EVALUATABLE_VISITOR)) {
if (session.getDatabase().getSettings().nestedJoins) {
// need to check that all added are bound to a table
on = on.optimize(session);
if (!f.isJoinOuter() && !f.isJoinOuterIndirect()) {
f.removeJoinCondition();
addCondition(on);
}
} else {
if (f.isJoinOuter()) {
// this will check if all columns exist - it may or may not throw an exception
on = on.optimize(session);
// it is not supported even if the columns exist
throw DbException.get(ErrorCode.UNSUPPORTED_OUTER_JOIN_CONDITION_1, on.getSQL());
}
f.removeJoinCondition();
// need to check that all added are bound to a table
on = on.optimize(session);
addCondition(on);
}
}
}
on = f.getFilterCondition();
if (on != null) {
if (!on.isEverything(ExpressionVisitor.EVALUATABLE_VISITOR)) {
f.removeFilterCondition();
addCondition(on);
}
}
// this is only important for subqueries, so they know
// the result columns are evaluatable
for (Expression e : expressions) {
e.setEvaluatable(f, true);
}
}
}
public String getPlanSQL() {
// can not use the field sqlStatement because the parameter
// indexes may be incorrect: ? may be in fact ?2 for a subquery
// but indexes may be set manually as well
Expression[] exprList = expressions.toArray(new Expression[expressions.size()]);
StatementBuilder buff = new StatementBuilder("SELECT");
if (distinct) {
buff.append(" DISTINCT");
}
for (int i = 0; i < visibleColumnCount; i++) {
buff.appendExceptFirst(",");
buff.append('\n');
buff.append(StringUtils.indent(exprList[i].getSQL(), 4, false));
}
buff.append("\nFROM ");
TableFilter filter = topTableFilter;
if (filter != null) {
buff.resetCount();
int i = 0;
do {
buff.appendExceptFirst("\n");
buff.append(filter.getPlanSQL(i++ > 0));
filter = filter.getJoin();
} while (filter != null);
} else {
buff.resetCount();
int i = 0;
for (TableFilter f : topFilters) {
do {
buff.appendExceptFirst("\n");
buff.append(f.getPlanSQL(i++ > 0));
f = f.getJoin();
} while (f != null);
}
}
if (condition != null) {
buff.append("\nWHERE ").append(StringUtils.unEnclose(condition.getSQL()));
}
if (groupIndex != null) {
buff.append("\nGROUP BY ");
buff.resetCount();
for (int gi : groupIndex) {
Expression g = exprList[gi];
g = g.getNonAliasExpression();
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(g.getSQL()));
}
}
if (group != null) {
buff.append("\nGROUP BY ");
buff.resetCount();
for (Expression g : group) {
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(g.getSQL()));
}
}
if (having != null) {
// could be set in addGlobalCondition
// in this case the query is not run directly, just getPlanSQL is
// called
Expression h = having;
buff.append("\nHAVING ").append(StringUtils.unEnclose(h.getSQL()));
} else if (havingIndex >= 0) {
Expression h = exprList[havingIndex];
buff.append("\nHAVING ").append(StringUtils.unEnclose(h.getSQL()));
}
if (sort != null) {
buff.append("\nORDER BY ").append(sort.getSQL(exprList, visibleColumnCount));
}
if (orderList != null) {
buff.append("\nORDER BY ");
buff.resetCount();
for (SelectOrderBy o : orderList) {
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(o.getSQL()));
}
}
if (limitExpr != null) {
buff.append("\nLIMIT ").append(StringUtils.unEnclose(limitExpr.getSQL()));
if (offsetExpr != null) {
buff.append(" OFFSET ").append(StringUtils.unEnclose(offsetExpr.getSQL()));
}
}
if (sampleSize != 0) {
buff.append("\nSAMPLE_SIZE ").append(sampleSize);
}
if (isForUpdate) {
buff.append("\nFOR UPDATE");
}
if (isQuickAggregateQuery) {
buff.append("\n/* direct lookup */");
}
if (isDistinctQuery) {
buff.append("\n/* distinct */");
}
if (sortUsingIndex) {
buff.append("\n/* index sorted */");
}
if (isGroupQuery) {
if (isGroupSortedQuery) {
buff.append("\n/* group sorted */");
}
}
// buff.append("\n/* cost: " + cost + " */");
return buff.toString();
}
public void setHaving(Expression having) {
this.having = having;
}
public int getColumnCount() {
return visibleColumnCount;
}
public TableFilter getTopTableFilter() {
return topTableFilter;
}
public ArrayList<Expression> getExpressions() {
return expressions;
}
public void setForUpdate(boolean b) {
this.isForUpdate = b;
if (session.getDatabase().getSettings().selectForUpdateMvcc && session.getDatabase().isMultiVersion()) {
isForUpdateMvcc = b;
}
}
public void mapColumns(ColumnResolver resolver, int level) {
for (Expression e : expressions) {
e.mapColumns(resolver, level);
}
if (condition != null) {
condition.mapColumns(resolver, level);
}
}
public void setEvaluatable(TableFilter tableFilter, boolean b) {
for (Expression e : expressions) {
e.setEvaluatable(tableFilter, b);
}
if (condition != null) {
condition.setEvaluatable(tableFilter, b);
}
}
/**
* Check if this is an aggregate query with direct lookup, for example a
* query of the type SELECT COUNT(*) FROM TEST or
* SELECT MAX(ID) FROM TEST.
*
* @return true if a direct lookup is possible
*/
public boolean isQuickAggregateQuery() {
return isQuickAggregateQuery;
}
public void addGlobalCondition(Parameter param, int columnId, int comparisonType) {
addParameter(param);
Expression comp;
Expression col = expressions.get(columnId);
col = col.getNonAliasExpression();
if (col.isEverything(ExpressionVisitor.QUERY_COMPARABLE_VISITOR)) {
comp = new Comparison(session, comparisonType, col, param);
} else {
// this condition will always evaluate to true, but need to
// add the parameter, so it can be set later
comp = new Comparison(session, Comparison.EQUAL_NULL_SAFE, param, param);
}
comp = comp.optimize(session);
boolean addToCondition = true;
if (isGroupQuery) {
addToCondition = false;
for (int i = 0; groupIndex != null && i < groupIndex.length; i++) {
if (groupIndex[i] == columnId) {
addToCondition = true;
break;
}
}
if (!addToCondition) {
if (havingIndex >= 0) {
having = expressions.get(havingIndex);
}
if (having == null) {
having = comp;
} else {
having = new ConditionAndOr(ConditionAndOr.AND, having, comp);
}
}
}
if (addToCondition) {
if (condition == null) {
condition = comp;
} else {
condition = new ConditionAndOr(ConditionAndOr.AND, condition, comp);
}
}
}
public void updateAggregate(Session s) {
for (Expression e : expressions) {
e.updateAggregate(s);
}
if (condition != null) {
condition.updateAggregate(s);
}
if (having != null) {
having.updateAggregate(s);
}
}
public boolean isEverything(ExpressionVisitor visitor) {
switch(visitor.getType()) {
case ExpressionVisitor.DETERMINISTIC: {
if (isForUpdate) {
return false;
}
for (int i = 0, size = filters.size(); i < size; i++) {
TableFilter f = filters.get(i);
if (!f.getTable().isDeterministic()) {
return false;
}
}
break;
}
case ExpressionVisitor.SET_MAX_DATA_MODIFICATION_ID: {
for (int i = 0, size = filters.size(); i < size; i++) {
TableFilter f = filters.get(i);
long m = f.getTable().getMaxDataModificationId();
visitor.addDataModificationId(m);
}
break;
}
case ExpressionVisitor.EVALUATABLE: {
if (!session.getDatabase().getSettings().optimizeEvaluatableSubqueries) {
return false;
}
break;
}
case ExpressionVisitor.GET_DEPENDENCIES: {
for (int i = 0, size = filters.size(); i < size; i++) {
TableFilter f = filters.get(i);
Table table = f.getTable();
visitor.addDependency(table);
table.addDependencies(visitor.getDependencies());
}
break;
}
default:
}
ExpressionVisitor v2 = visitor.incrementQueryLevel(1);
boolean result = true;
for (int i = 0, size = expressions.size(); i < size; i++) {
Expression e = expressions.get(i);
if (!e.isEverything(v2)) {
result = false;
break;
}
}
if (result && condition != null && !condition.isEverything(v2)) {
result = false;
}
if (result && having != null && !having.isEverything(v2)) {
result = false;
}
return result;
}
public boolean isReadOnly() {
return isEverything(ExpressionVisitor.READONLY_VISITOR);
}
public boolean isCacheable() {
return !isForUpdate;
}
public int getType() {
return CommandInterface.SELECT;
}
public boolean allowGlobalConditions() {
if (offsetExpr == null && (limitExpr == null || sort == null)) {
return true;
}
return false;
}
}