org.lealone.sql.query.YieldableSelectUnion Maven / Gradle / Ivy
/*
* Copyright Lealone Database Group.
* Licensed under the Server Side Public License, v 1.
* Initial Developer: zhh
*/
package org.lealone.sql.query;
import org.lealone.common.exceptions.DbException;
import org.lealone.db.async.AsyncHandler;
import org.lealone.db.async.AsyncResult;
import org.lealone.db.result.LocalResult;
import org.lealone.db.result.Result;
import org.lealone.db.result.ResultTarget;
import org.lealone.db.session.SessionStatus;
import org.lealone.db.value.Value;
import org.lealone.db.value.ValueInt;
import org.lealone.db.value.ValueNull;
import org.lealone.sql.executor.YieldableBase;
import org.lealone.sql.expression.Expression;
import org.lealone.sql.expression.ValueExpression;
class YieldableSelectUnion extends YieldableQueryBase {
private final SelectUnion selectUnion;
private final ResultTarget target;
private Expression limitExpr;
private boolean insertFromSelect;
private YieldableBase leftYieldableQuery;
private YieldableBase rightYieldableQuery;
private int columnCount;
private LocalResult result;
private Result leftRows;
private Result rightRows;
private LocalResult temp;
private int rowNumber;
private boolean done;
public YieldableSelectUnion(SelectUnion selectUnion, int maxRows, boolean scrollable,
AsyncHandler> asyncHandler, ResultTarget target) {
super(selectUnion, maxRows, scrollable, asyncHandler);
this.selectUnion = selectUnion;
this.target = target;
}
@Override
protected boolean startInternal() {
selectUnion.fireBeforeSelectTriggers();
// union doesn't always know the parameter list of the left and right queries
if (maxRows != 0) {
// maxRows is set (maxRows 0 means no limit)
int l;
if (limitExpr == null) {
l = -1;
} else {
Value v = limitExpr.getValue(session);
l = v == ValueNull.INSTANCE ? -1 : v.getInt();
}
if (l < 0) {
// for limitExpr, 0 means no rows, and -1 means no limit
l = maxRows;
} else {
l = Math.min(l, maxRows);
}
limitExpr = ValueExpression.get(ValueInt.get(l));
}
if (session.getDatabase().getSettings().optimizeInsertFromSelect) {
if (selectUnion.unionType == SelectUnion.UNION_ALL && target != null) {
if (selectUnion.sort == null && !selectUnion.distinct && maxRows == 0
&& selectUnion.offsetExpr == null && limitExpr == null) {
insertFromSelect = true;
leftYieldableQuery = selectUnion.left.createYieldableQuery(0, false, null, target);
rightYieldableQuery = selectUnion.right.createYieldableQuery(0, false, null, target);
return false;
}
}
}
columnCount = selectUnion.left.getColumnCount();
result = new LocalResult(session, selectUnion.expressionArray, columnCount);
if (selectUnion.sort != null) {
result.setSortOrder(selectUnion.sort);
}
if (selectUnion.distinct) {
selectUnion.left.setDistinct(true);
selectUnion.right.setDistinct(true);
result.setDistinct();
}
switch (selectUnion.unionType) {
case SelectUnion.UNION:
case SelectUnion.EXCEPT:
selectUnion.left.setDistinct(true);
selectUnion.right.setDistinct(true);
result.setDistinct();
break;
case SelectUnion.UNION_ALL:
break;
case SelectUnion.INTERSECT:
selectUnion.left.setDistinct(true);
selectUnion.right.setDistinct(true);
temp = new LocalResult(session, selectUnion.expressionArray, columnCount);
temp.setDistinct();
break;
default:
DbException.throwInternalError("type=" + selectUnion.unionType);
}
leftYieldableQuery = selectUnion.left.createYieldableQuery(0, false, null, null);
rightYieldableQuery = selectUnion.right.createYieldableQuery(0, false, null, null);
return false;
}
@Override
protected void stopInternal() {
}
@Override
protected void executeInternal() {
if (insertFromSelect) {
if (leftYieldableQuery != null) {
leftYieldableQuery.run();
if (leftYieldableQuery.isStopped()) {
leftYieldableQuery = null;
}
}
if (leftYieldableQuery == null && rightYieldableQuery != null) {
rightYieldableQuery.run();
if (rightYieldableQuery.isStopped()) {
rightYieldableQuery = null;
}
}
}
switch (selectUnion.unionType) {
case SelectUnion.UNION_ALL:
case SelectUnion.UNION: {
if (leftYieldableQuery != null && runLeftQuery()) {
return;
}
if (leftRows != null && addLeftRows()) {
return;
}
if (rightYieldableQuery != null && runRightQuery()) {
return;
}
if (rightRows != null && addRightRows()) {
return;
}
break;
}
case SelectUnion.EXCEPT: {
if (leftYieldableQuery != null && runLeftQuery()) {
return;
}
if (leftRows != null && addLeftRows()) {
return;
}
if (rightYieldableQuery != null && runRightQuery()) {
return;
}
if (rightRows != null) {
while (rightRows.next()) {
result.removeDistinct(convert(rightRows.currentRow(), columnCount));
if (yieldIfNeeded(++rowNumber)) {
return;
}
}
rightRows = null;
}
break;
}
case SelectUnion.INTERSECT: {
if (leftYieldableQuery != null && runLeftQuery()) {
return;
}
if (leftRows != null) {
while (leftRows.next()) {
temp.addRow(convert(leftRows.currentRow(), columnCount));
if (yieldIfNeeded(++rowNumber)) {
return;
}
}
leftRows = null;
}
if (rightYieldableQuery != null && runRightQuery()) {
return;
}
if (rightRows != null) {
while (rightRows.next()) {
Value[] values = convert(rightRows.currentRow(), columnCount);
if (temp.containsDistinct(values)) {
result.addRow(values);
}
if (yieldIfNeeded(++rowNumber)) {
return;
}
}
rightRows = null;
}
break;
}
default:
DbException.throwInternalError("type=" + selectUnion.unionType);
}
if (!done) {
if (selectUnion.offsetExpr != null) {
result.setOffset(selectUnion.offsetExpr.getValue(session).getInt());
}
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
if (v != ValueNull.INSTANCE) {
result.setLimit(v.getInt());
}
}
rowNumber = 0;
result.done();
done = true;
}
if (target == null) {
setResult(result, result.getRowCount());
} else {
while (result.next()) {
target.addRow(result.currentRow());
if (yieldIfNeeded(++rowNumber)) {
return;
}
}
result.close();
}
session.setStatus(SessionStatus.STATEMENT_COMPLETED);
}
private boolean runLeftQuery() {
if (leftRows == null) {
leftYieldableQuery.run();
if (leftYieldableQuery.isStopped()) {
rowNumber = 0;
leftRows = leftYieldableQuery.getResult();
leftYieldableQuery = null;
return false;
}
}
return true;
}
private boolean runRightQuery() {
if (rightRows == null) {
rightYieldableQuery.run();
if (rightYieldableQuery.isStopped()) {
rowNumber = 0;
rightRows = rightYieldableQuery.getResult();
rightYieldableQuery = null;
return false;
}
}
return true;
}
private boolean addLeftRows() {
while (leftRows.next()) {
result.addRow(convert(leftRows.currentRow(), columnCount));
if (yieldIfNeeded(++rowNumber)) {
return true;
}
}
leftRows = null;
return false;
}
private boolean addRightRows() {
while (rightRows.next()) {
result.addRow(convert(rightRows.currentRow(), columnCount));
if (yieldIfNeeded(++rowNumber)) {
return true;
}
}
rightRows = null;
return false;
}
private Value[] convert(Value[] values, int columnCount) {
Value[] newValues;
if (columnCount == values.length) {
// re-use the array if possible
newValues = values;
} else {
// create a new array if needed,
// for the value hash set
newValues = new Value[columnCount];
}
for (int i = 0; i < columnCount; i++) {
Expression e = selectUnion.expressions.get(i);
newValues[i] = values[i].convertTo(e.getType());
}
return newValues;
}
}
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