final FromItem fromItem = query.getFromClause().getItem(0);
final Table table = fromItem.getTable();
if (table != null) {
// check for approximate SELECT COUNT(*) queries
if (selectItems.size() == 1) {
final SelectItem selectItem = query.getSelectClause().getItem(0);
if (SelectItem.isCountAllItem(selectItem)) {
final boolean functionApproximationAllowed = selectItem.isFunctionApproximationAllowed();
if (isMainSchemaTable(table)) {
logger.debug("Query is a COUNT query with {} where items. Trying executeCountQuery(...)",
whereItems.size());
final Number count = executeCountQuery(table, whereItems, functionApproximationAllowed);
if (count == null) {
logger.debug("DataContext did not return any count query results. Proceeding with manual counting.");
} else {
List<Row> data = new ArrayList<Row>(1);
final DataSetHeader header = new SimpleDataSetHeader(new SelectItem[] { selectItem });
data.add(new DefaultRow(header, new Object[] { count }));
return new InMemoryDataSet(header, data);
}
}
}
}
// check for lookup query by primary key
if (whereItems.size() == 1) {
final FilterItem whereItem = whereItems.get(0);
final SelectItem selectItem = whereItem.getSelectItem();
if (!whereItem.isCompoundFilter() && selectItem != null && selectItem.getColumn() != null) {
final Column column = selectItem.getColumn();
if (column.isPrimaryKey() && whereItem.getOperator() == OperatorType.EQUALS_TO) {
logger.debug("Query is a primary key lookup query. Trying executePrimaryKeyLookupQuery(...)");
if (table != null) {
if (isMainSchemaTable(table)) {
final Object operand = whereItem.getOperand();