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 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);
}
}
@Override
public int update() {
tableFilter.startQuery(session);
tableFilter.reset();
Table table = tableFilter.getTable();
session.getUser().checkRight(table, Right.DELETE);
table.fire(session, Trigger.DELETE, true);
// 直到事务commit或rollback时才解琐，见org.h2.engine.Session.unlockAll()
table.lock(session, true, false);
RowList rows = new RowList(session);
int limitRows = -1;
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
if (v != ValueNull.INSTANCE) {
limitRows = v.getInt();
}
}
try {
setCurrentRowNumber(0);
int count = 0;
// 比如delete from DeleteTest limit 0，
// 此时limitRows为0，不删除任何行
while (limitRows != 0 && tableFilter.next()) {
setCurrentRowNumber(rows.size() + 1);
// condition.getBooleanValue(session)内部会取当前行与之比较，
// 比如，如果是ExpressionColumn，那么就由它对应的列，取得列id，
// 然后在从当前行中按列id取当前行value数组中对应元素
if (condition == null || Boolean.TRUE.equals(condition.getBooleanValue(session))) {
Row row = tableFilter.get();
boolean done = false;
if (table.fireRow()) {
done = table.fireBeforeRow(session, row, null);
}
if (!done) {
rows.add(row);
}
count++;
if (limitRows >= 0 && count >= limitRows) {
break;
}
}
}
int rowScanCount = 0;
for (rows.reset(); rows.hasNext(); ) {
if ((++rowScanCount & 127) == 0) {
checkCanceled();
}
Row row = rows.next();
table.removeRow(session, row);
session.log(table, UndoLogRecord.DELETE, row);
}
if (table.fireRow()) {
for (rows.reset(); rows.hasNext(); ) {
Row row = rows.next();
table.fireAfterRow(session, row, null, false);
}
}
table.fire(session, Trigger.DELETE, false);
return count;
} finally {
rows.close();
}
}
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);
}
}