/** Returns a new query context. */
public static QueryContext allocate() {
QueryContext queryContext = _freeList.allocate();
if (queryContext == null) queryContext = new QueryContext();
queryContext.clearParameters();
queryContext._limit = -1;
queryContext._isNonLocking = false;
return queryContext;
}
/** Executes the query. */
public boolean exists(QueryContext context, DbTransaction xa) throws SQLException {
SelectResult result = SelectResult.create(_nullExprs, null);
try {
TableIterator[] rows = result.initRows(getFromItems());
context.init(xa, rows, isReadOnly());
return execute(result, rows, context, xa);
} catch (IOException e) {
throw new SQLExceptionWrapper(e);
} finally {
context.unlock();
result.close();
}
}
/** validate the constraint. */
@Override
public void validate(TableIterator[] sourceRows, QueryContext context, Transaction xa)
throws SQLException {
try {
TableIterator sourceRow = sourceRows[0];
byte[] sourceBuffer = sourceRow.getBuffer();
int sourceOffset = sourceRow.getRowOffset();
byte[] buffer = context.getBuffer();
int length = _column.getLength();
if (length <= 0) return;
BTree index = _column.getIndex();
long value = index.lookup(buffer, 0, length);
if (value != 0) {
Table table = sourceRow.getTable();
long blockId = sourceRow.getBlockId();
throw new SQLException(
L.l(
"`{0}' in {1}.{2} fails uniqueness constraint.",
_column.getString(blockId, sourceBuffer, sourceOffset),
table.getName(),
_column.getName()));
}
} catch (IOException e) {
throw new SQLExceptionWrapper(e);
}
}
/** Executes the query. */
public void execute(QueryContext queryContext, Transaction xa) throws SQLException {
try {
_factory.create();
} catch (java.io.IOException e) {
throw new SQLExceptionWrapper(e);
}
queryContext.setRowUpdateCount(0);
}
private java.sql.ResultSet executeQuery(Query query, QueryContext queryContext)
throws SQLException {
DbTransaction xa = getConnectionImpl().getTransaction();
queryContext.setNonLocking();
SelectCursor result = query.executeCursor(queryContext, xa);
return new CursorResultSetImpl(this, queryContext, result);
}
/**
* Evaluates aggregate functions during the group phase.
*
* @param context the current database tuple
*/
public void evalGroup(QueryContext context) throws SQLException {
if (_expr.isNull(context)) return;
switch (_type) {
default:
{
String value = _expr.evalString(context);
context.setGroupString(_index, value);
}
break;
}
}
public void init(QueryContext queryContext) throws SQLException {
init(queryContext.getTransaction());
_queryContext = queryContext;
}
public String evalString(QueryContext context) {
return context.getGroupString(_index);
}
