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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.Collation;
import org.hsqldb.types.Type;
/*
* Implementation of ORDER BY and LIMIT properties of query expressions.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.3.0
* @since 1.9.0
*/
public final class SortAndSlice {
static final SortAndSlice noSort = new SortAndSlice();
static final int[] defaultLimits = new int[] {
0, Integer.MAX_VALUE, Integer.MAX_VALUE
};
//
public int[] sortOrder;
public boolean[] sortDescending;
public boolean[] sortNullsLast;
public Collation[] collations;
boolean sortUnion;
HsqlArrayList exprList = new HsqlArrayList();
ExpressionOp limitCondition;
int columnCount;
boolean hasNullsLast;
boolean strictLimit;
boolean zeroLimit;
boolean usingIndex;
boolean allDescending;
public boolean skipSort = false; // true when result can be used as is
public boolean skipFullResult = false; // true when result can be sliced as is
public Index index;
public Table primaryTable;
public Index primaryTableIndex;
public int[] colIndexes;
public boolean isGenerated;
public SortAndSlice() {}
public HsqlArrayList getExpressionList() {
return exprList;
}
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(ExpressionOp expression) {
limitCondition = expression;
}
public void setStrictLimit() {
strictLimit = true;
}
public void setZeroLimit() {
zeroLimit = true;
}
public void setUsingIndex() {
usingIndex = true;
}
public void prepareSingleColumn(int colIndex) {
sortOrder = new int[1];
sortDescending = new boolean[1];
sortNullsLast = new boolean[1];
sortOrder[0] = colIndex;
}
public void prepareMultiColumn(int count) {
sortOrder = new int[count];
sortDescending = new boolean[count];
sortNullsLast = new boolean[count];
for (int i = 0; i < count; i++) {
sortOrder[i] = i;
}
}
public void prepare(int degree) {
columnCount = exprList.size();
if (columnCount == 0) {
return;
}
sortOrder = new int[columnCount + degree];
sortDescending = new boolean[columnCount + degree];
sortNullsLast = new boolean[columnCount + degree];
ArrayUtil.fillSequence(sortOrder);
for (int i = 0; i < columnCount; i++) {
ExpressionOrderBy sort = (ExpressionOrderBy) exprList.get(i);
sortDescending[i] = sort.isDescending();
sortNullsLast[i] = sort.isNullsLast();
hasNullsLast |= sortNullsLast[i];
}
}
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 (sort.collation != null) {
if (collations == null) {
collations = new Collation[columnCount];
}
collations[i] = sort.collation;
}
}
}
void setSortIndex(QuerySpecification select) {
if (this == noSort) {
return;
}
if (isGenerated) {
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 (select == null) {
return;
}
if (select.isDistinctSelect || select.isGrouped
|| select.isAggregated) {
if (!select.isSimpleDistinct) {
return;
}
}
if (columnCount == 0) {
if (limitCondition == null) {
return;
}
skipFullResult = true;
return;
}
if (collations != null) {
return;
}
colIndexes = new int[columnCount];
boolean isNullable = false;
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;
if (e.getColumn().getNullability()
!= SchemaObject.Nullability.NO_NULLS) {
isNullable = true;
}
}
if (hasNullsLast && isNullable) {
return;
}
int count = ArrayUtil.countTrueElements(sortDescending);
allDescending = count == columnCount;
if (!allDescending && count > 0) {
return;
}
primaryTable = select.rangeVariables[0].getTable();
primaryTableIndex = primaryTable.getFullIndexForColumns(colIndexes);
}
void setSortRange(QuerySpecification select) {
if (this == noSort) {
return;
}
if (primaryTableIndex == null) {
if (select.isSimpleDistinct) {
setSortIndex(select);
}
if (primaryTableIndex == null) {
return;
}
}
Index rangeIndex = select.rangeVariables[0].getSortIndex();
if (rangeIndex == null) {
// multi-index
return;
}
if (primaryTable != select.rangeVariables[0].rangeTable) {
return;
}
if (rangeIndex == primaryTableIndex) {
if (allDescending) {
boolean reversed = select.rangeVariables[0].reverseOrder();
if (!reversed) {
return;
}
}
skipSort = true;
skipFullResult = true;
} else if (!select.rangeVariables[0].joinConditions[0]
.hasIndexCondition()) {
if (select.rangeVariables[0].setSortIndex(primaryTableIndex,
allDescending)) {
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;
}
if (select.rangeVariables[0].hasSingleIndexCondition()) {
int[] colIndexes = rangeIndex.getColumns();
if (colIndexes[0] != ((ExpressionColumn) e).getColumnIndex()) {
return false;
}
if (opType == OpTypes.MAX) {
select.rangeVariables[0].reverseOrder();
}
} else if (select.rangeVariables[0].hasAnyIndexCondition()) {
return false;
} else {
Table table = select.rangeVariables[0].getTable();
Index index = table.getIndexForColumn(
session, ((ExpressionColumn) e).getColumnIndex());
if (index == null) {
return false;
}
Expression[] conditions = new Expression[]{
ExpressionLogical.newNotNullCondition(e) };
select.rangeVariables[0].joinConditions[0].addIndexCondition(
conditions, index, 1);
if (opType == OpTypes.MAX) {
select.rangeVariables[0].reverseOrder();
}
}
columnCount = 1;
sortOrder = new int[columnCount];
sortDescending = new boolean[columnCount];
sortNullsLast = new boolean[columnCount];
skipSort = true;
skipFullResult = true;
return true;
}
int[] getLimits(Session session, QueryExpression qe, int maxRows) {
if (this == noSort && maxRows == 0) {
return defaultLimits;
}
int skipRows = 0;
int limitRows = Integer.MAX_VALUE;
int limitFetch = Integer.MAX_VALUE;
boolean hasLimits = false;
if (hasLimit()) {
Integer value =
(Integer) limitCondition.getLeftNode().getValue(session);
if (value == null || value.intValue() < 0) {
throw Error.error(ErrorCode.X_2201X);
}
skipRows = value.intValue();
hasLimits = skipRows != 0;
if (limitCondition.getRightNode() != null) {
value =
(Integer) limitCondition.getRightNode().getValue(session);
if (value == null || value.intValue() < 0
|| (strictLimit && value.intValue() == 0)) {
throw Error.error(ErrorCode.X_2201W);
}
if (value.intValue() == 0 && !zeroLimit) {
limitRows = Integer.MAX_VALUE;
} else {
limitRows = value.intValue();
hasLimits = true;
}
}
}
if (maxRows != 0) {
if (maxRows < limitRows) {
limitRows = maxRows;
}
hasLimits = true;
}
boolean simpleLimit = false;
if (qe instanceof QuerySpecification) {
QuerySpecification select = (QuerySpecification) qe;
if (!select.isDistinctSelect && !select.isGrouped) {
simpleLimit = true;
}
if (select.isSimpleDistinct) {
simpleLimit = true;
}
}
if (hasLimits) {
if (simpleLimit && (!hasOrder() || skipSort)
&& (!hasLimit() || skipFullResult)) {
if (limitFetch - skipRows > limitRows) {
limitFetch = skipRows + limitRows;
}
}
return new int[] {
skipRows, limitRows, limitFetch
};
}
return defaultLimits;
}
public void setIndex(Session session, TableBase table) {
index = getNewIndex(session, table);
}
public Index getNewIndex(Session session, TableBase table) {
if (hasOrder()) {
Index orderIndex = table.createAndAddIndexStructure(session, null,
sortOrder, sortDescending, sortNullsLast, false, false, false);
if (collations != null) {
for (int i = 0; i < columnCount; i++) {
if (collations[i] != null) {
Type type = orderIndex.getColumnTypes()[i];
type = Type.getType(type.typeCode,
type.getCharacterSet(),
collations[i], type.precision,
type.scale);
orderIndex.getColumnTypes()[i] = type;
}
}
}
return orderIndex;
}
return null;
}
}