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package org.hsqldb;
import org.hsqldb.error.Error;
import org.hsqldb.error.ErrorCode;
import org.hsqldb.index.Index;
import org.hsqldb.lib.ArrayUtil;
import org.hsqldb.lib.HsqlArrayList;
import org.hsqldb.types.Type;
/*
* Implementation of ORDER BY and LIMIT properties of query expressions.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.0.0
* @since 1.9.0
*/
public final class SortAndSlice {
final static SortAndSlice noSort = new SortAndSlice();
//
public int[] sortOrder;
public boolean[] sortDescending;
public boolean[] sortNullsLast;
boolean sortUnion;
HsqlArrayList exprList = new HsqlArrayList();
Expression limitCondition;
int columnCount;
boolean hasNullsLast;
public boolean skipSort = false; // true when result can be used as is
public boolean skipFullResult = false; // true when result can be sliced as is
int[] columnIndexes;
public Index index;
public boolean isGenerated;
SortAndSlice() {}
public boolean hasOrder() {
return exprList.size() != 0;
}
public boolean hasLimit() {
return limitCondition != null;
}
public int getOrderLength() {
return exprList.size();
}
public void addOrderExpression(Expression e) {
exprList.add(e);
}
public void addLimitCondition(Expression expression) {
limitCondition = expression;
}
public void prepare(QuerySpecification select) {
columnCount = exprList.size();
if (columnCount == 0) {
return;
}
sortOrder = new int[columnCount];
sortDescending = new boolean[columnCount];
sortNullsLast = new boolean[columnCount];
for (int i = 0; i < columnCount; i++) {
ExpressionOrderBy sort = (ExpressionOrderBy) exprList.get(i);
if (sort.getLeftNode().queryTableColumnIndex == -1) {
sortOrder[i] = select.indexStartOrderBy + i;
} else {
sortOrder[i] = sort.getLeftNode().queryTableColumnIndex;
}
sortDescending[i] = sort.isDescending();
sortNullsLast[i] = sort.isNullsLast();
hasNullsLast |= sortNullsLast[i];
}
if (select == null || hasNullsLast) {
return;
}
if (select.isDistinctSelect || select.isGrouped
|| select.isAggregated) {
return;
}
int[] colIndexes = new int[columnCount];
for (int i = 0; i < columnCount; i++) {
Expression e = ((Expression) exprList.get(i)).getLeftNode();
if (e.getType() != OpTypes.COLUMN) {
return;
}
if (((ExpressionColumn) e).getRangeVariable()
!= select.rangeVariables[0]) {
return;
}
colIndexes[i] = e.columnIndex;
}
this.columnIndexes = colIndexes;
}
void setSortRange(QuerySpecification select) {
if (isGenerated) {
return;
}
if (columnCount == 0) {
if (limitCondition == null) {
return;
}
if (select.isDistinctSelect || select.isGrouped
|| select.isAggregated) {
return;
}
skipFullResult = true;
return;
}
for (int i = 0; i < columnCount; i++) {
ExpressionOrderBy sort = (ExpressionOrderBy) exprList.get(i);
Type dataType = sort.getLeftNode().getDataType();
if (dataType.isArrayType() || dataType.isLobType()) {
throw Error.error(ErrorCode.X_42534);
}
}
if (columnIndexes == null) {
return;
}
int[] colIndexes;
Index rangeIndex = select.rangeVariables[0].getSortIndex();
if (rangeIndex == null) {
return;
}
colIndexes = rangeIndex.getColumns();
int count = ArrayUtil.countTrueElements(sortDescending);
boolean allDescending = count == columnCount;
if (!allDescending && count > 0) {
return;
}
if (!select.rangeVariables[0].hasIndexCondition()) {
Table table = select.rangeVariables[0].getTable();
Index index = table.getFullIndexForColumns(columnIndexes);
if (index != null) {
if (select.rangeVariables[0].setSortIndex(index,
allDescending)) {
skipSort = true;
skipFullResult = true;
}
}
} else if (ArrayUtil.haveEqualArrays(columnIndexes, colIndexes,
columnIndexes.length)) {
if (allDescending) {
boolean reversed = select.rangeVariables[0].reverseOrder();
if (!reversed) {
return;
}
}
skipSort = true;
skipFullResult = true;
}
}
public boolean prepareSpecial(Session session, QuerySpecification select) {
Expression e = select.exprColumns[select.indexStartAggregates];
int opType = e.getType();
e = e.getLeftNode();
if (e.getType() != OpTypes.COLUMN) {
return false;
}
if (((ExpressionColumn) e).getRangeVariable()
!= select.rangeVariables[0]) {
return false;
}
Index rangeIndex = select.rangeVariables[0].getSortIndex();
if (rangeIndex == null) {
return false;
}
int[] colIndexes = rangeIndex.getColumns();
if (select.rangeVariables[0].hasIndexCondition()) {
if (colIndexes[0] != ((ExpressionColumn) e).getColumnIndex()) {
return false;
}
if (opType == OpTypes.MAX) {
select.rangeVariables[0].reverseOrder();
}
} else {
Table table = select.rangeVariables[0].getTable();
Index index = table.getIndexForColumn(
session, ((ExpressionColumn) e).getColumnIndex());
if (index == null) {
return false;
}
if (!select.rangeVariables[0].setSortIndex(index,
opType == OpTypes.MAX)) {
return false;
}
}
columnCount = 1;
sortOrder = new int[columnCount];
sortDescending = new boolean[columnCount];
sortNullsLast = new boolean[columnCount];
columnIndexes = new int[columnCount];
columnIndexes[0] = e.columnIndex;
skipSort = true;
skipFullResult = true;
return true;
}
public int getLimitStart(Session session) {
if (limitCondition != null) {
Integer limit =
(Integer) limitCondition.getLeftNode().getValue(session);
if (limit != null) {
return limit.intValue();
}
}
return 0;
}
public int getLimitCount(Session session, int rowCount) {
int limitCount = 0;
if (limitCondition != null) {
Integer limit =
(Integer) limitCondition.getRightNode().getValue(session);
if (limit != null) {
limitCount = limit.intValue();
}
}
if (rowCount != 0 && (limitCount == 0 || rowCount < limitCount)) {
limitCount = rowCount;
}
return limitCount;
}
public void setIndex(Session session, TableBase table) {
try {
index = table.createAndAddIndexStructure(session, null, sortOrder,
sortDescending, sortNullsLast, false, false, false);
} catch (Throwable t) {
throw Error.runtimeError(ErrorCode.U_S0500, "SortAndSlice");
}
}
}