@Override
public Cursor find(Session session, SearchRow first, SearchRow last) {
long min, max;
if (first == null || mainIndexColumn < 0) {
min = Long.MIN_VALUE;
} else {
Value v = first.getValue(mainIndexColumn);
if (v == null) {
min = 0;
} else {
min = v.getLong();
}
}
if (last == null || mainIndexColumn < 0) {
max = Long.MAX_VALUE;
} else {
Value v = last.getValue(mainIndexColumn);
if (v == null) {
max = Long.MAX_VALUE;
} else {
max = v.getLong();
}
}
TransactionMap<Value, Value> map = getMap(session);
return new MVStoreCursor(session, map.keyIterator(ValueLong.get(min)), max);
}
@Override
public Cursor find(Session session, SearchRow first, SearchRow last) {
ValueLong min, max;
if (first == null) {
min = MIN;
} else if (mainIndexColumn < 0) {
min = ValueLong.get(first.getKey());
} else {
ValueLong v = (ValueLong) first.getValue(mainIndexColumn);
if (v == null) {
min = ValueLong.get(first.getKey());
} else {
min = v;
}
}
if (last == null) {
max = MAX;
} else if (mainIndexColumn < 0) {
max = ValueLong.get(last.getKey());
} else {
ValueLong v = (ValueLong) last.getValue(mainIndexColumn);
if (v == null) {
max = ValueLong.get(last.getKey());
} else {
max = v;
}
}
TransactionMap<Value, Value> map = getMap(session);
return new MVStoreCursor(session, map.entryIterator(min), max);
}
/**
* Check if one of the columns is NULL and multiple rows with NULL are allowed using the current
* compatibility mode for unique indexes. Note: NULL behavior is complicated in SQL.
*
* @param newRow the row to check
* @return true if one of the columns is null and multiple nulls in unique indexes are allowed
*/
protected boolean containsNullAndAllowMultipleNull(SearchRow newRow) {
Mode mode = database.getMode();
// 1. 对于唯一索引，必须完全唯一，适用于Derby/HSQLDB/MSSQLServer
if (mode.uniqueIndexSingleNull) {
// 不允许出现:
// (x, null)
// (x, null)
// 也不允许出现:
// (null, null)
// (null, null)
return false;
} else if (mode.uniqueIndexSingleNullExceptAllColumnsAreNull) {
// 2. 对于唯一索引，索引记录可以全为null，适用于Oracle
// 不允许出现:
// (x, null)
// (x, null)
// 但是允许出现:
// (null, null)
// (null, null)
for (int index : columnIds) {
Value v = newRow.getValue(index);
if (v != ValueNull.INSTANCE) {
return false;
}
}
return true;
}
// 3. 对于唯一索引，只要一个为null，就是合法的，适用于REGULAR(即H2)/DB2/MySQL/PostgreSQL
// 即允许出现:
// (x, null)
// (x, null)
// 也允许出现:
// (null, null)
// (null, null)
// 也就是说，只要相同的两条索引记录包含null即可
for (int index : columnIds) {
Value v = newRow.getValue(index);
if (v == ValueNull.INSTANCE) {
return true;
}
}
// 4. 对于唯一索引，没有null时是不允许出现两条相同的索引记录的
return false;
}
/** {@inheritDoc} */
@Override
public int compareRows(SearchRow rowData, SearchRow compare) {
if (rowData == compare) return 0;
for (int i = 0, len = indexColumns.length; i < len; i++) {
int index = columnIds[i];
Value v1 = rowData.getValue(index);
Value v2 = compare.getValue(index);
if (v1 == null || v2 == null) return 0;
int c = compareValues(v1, v2, indexColumns[i].sortType);
if (c != 0) return c;
}
return 0;
}
@Override
public int compareRows(SearchRow rowData, SearchRow compare) { // 只比较索引字段，并不一定是所有字段
if (rowData == compare) {
return 0;
}
for (int i = 0, len = indexColumns.length; i < len; i++) {
int index = columnIds[i];
Value v = compare.getValue(index);
if (v == null) { // 只要compare中有null值就认为无法比较，直接认为rowData和compare相等(通常在查询时在where中再比较)
// can't compare further
return 0;
}
int c = compareValues(rowData.getValue(index), v, indexColumns[i].sortType);
if (c != 0) {
return c;
}
}
return 0;
}
@Override
public Cursor findFirstOrLast(Session session, boolean first) {
if (closed) {
throw DbException.throwInternalError();
}
if (first) {
// TODO optimization: this loops through NULL
Cursor cursor = find(session, null, null);
while (cursor.next()) {
SearchRow row = cursor.getSearchRow();
Value v = row.getValue(columnIds[0]);
if (v != ValueNull.INSTANCE) {
return cursor;
}
}
return cursor;
}
TreeNode x = root, n;
while (x != null) {
n = x.right;
if (n == null) {
break;
}
x = n;
}
TreeCursor cursor = new TreeCursor(this, x, null, null);
if (x == null) {
return cursor;
}
// TODO optimization: this loops through NULL elements
do {
SearchRow row = cursor.getSearchRow();
if (row == null) {
break;
}
Value v = row.getValue(columnIds[0]);
if (v != ValueNull.INSTANCE) {
return cursor;
}
} while (cursor.previous());
return cursor;
}
/**
* Get the key from the row.
*
* @param row the row
* @param ifEmpty the value to use if the row is empty
* @param ifNull the value to use if the column is NULL
* @return the key
*/
long getKey(SearchRow row, long ifEmpty, long ifNull) {
if (row == null) {
return ifEmpty;
}
Value v = row.getValue(mainIndexColumn);
if (v == null) {
throw DbException.throwInternalError(row.toString());
} else if (v == ValueNull.INSTANCE) {
return ifNull;
}
return v.getLong();
}
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;
}
}
}
public Cursor find(Session session, SearchRow first, SearchRow last) {
if (recursive) {
if (view.getRecursiveResult() != null) {
ResultInterface r = view.getRecursiveResult();
r.reset();
return new ViewCursor(table, r);
}
if (query == null) {
query = (Query) createSession.prepare(querySQL, true);
planSQL = query.getPlanSQL();
}
if (!(query instanceof SelectUnion)) {
throw DbException.get(ErrorCode.SYNTAX_ERROR_2, "recursive queries without UNION ALL");
}
SelectUnion union = (SelectUnion) query;
if (union.getUnionType() != SelectUnion.UNION_ALL) {
throw DbException.get(ErrorCode.SYNTAX_ERROR_2, "recursive queries without UNION ALL");
}
Query left = union.getLeft();
ResultInterface r = left.query(0);
LocalResult result = union.getEmptyResult();
while (r.next()) {
result.addRow(r.currentRow());
}
Query right = union.getRight();
r.reset();
view.setRecursiveResult(r);
while (true) {
r = right.query(0);
if (r.getRowCount() == 0) {
break;
}
while (r.next()) {
result.addRow(r.currentRow());
}
r.reset();
view.setRecursiveResult(r);
}
return new ViewCursor(table, result);
}
ArrayList<Parameter> paramList = query.getParameters();
for (int i = 0; originalParameters != null && i < originalParameters.size(); i++) {
Parameter orig = originalParameters.get(i);
int idx = orig.getIndex();
Value value = orig.getValue(session);
setParameter(paramList, idx, value);
}
int len;
if (first != null) {
len = first.getColumnCount();
} else if (last != null) {
len = last.getColumnCount();
} else {
len = 0;
}
int idx = originalParameters == null ? 0 : originalParameters.size();
idx += view.getParameterOffset();
for (int i = 0; i < len; i++) {
if (first != null) {
Value v = first.getValue(i);
if (v != null) {
int x = idx++;
setParameter(paramList, x, v);
}
}
// for equality, only one parameter is used (first == last)
if (last != null && indexMasks[i] != IndexCondition.EQUALITY) {
Value v = last.getValue(i);
if (v != null) {
int x = idx++;
setParameter(paramList, x, v);
}
}
}
ResultInterface result = query.query(0);
return new ViewCursor(table, result);
}