private boolean columnMatched(TableColumn c1, TableColumn c2) {
Utils.checkTrue(!c1.getFullName().equals(c2.getFullName()));
if (matchingName) {
return c1.getColumnName().equals(c2.getColumnName());
}
return true;
}
public SQLSkeleton inferSQLSkeleton() {
SQLSkeleton skeleton = new SQLSkeleton(this.inputTables, this.outputTable);
// first get all tables
List<TableInstance> tables = new LinkedList<TableInstance>();
List<TableColumn> outputColumns = outputTable.getColumns();
// FIXME no consider repetitive columns
// for(TableColumn column : outputColumns) {
// TableInstance t = TableUtils.findFirstTableWithMatchedColumn(column.getColumnName(),
// this.inputTables);
// if(t != null && !tables.contains(t)) {
// tables.add(t);
// }
// }
tables.addAll(this.inputTables);
skeleton.addTables(tables);
Utils.checkTrue(skeleton.getTables().size() >= this.inputTables.size());
// all possible joining conditions
// join with keys
List<Pair<TableColumn, TableColumn>> p1list = this.getKeyPairs(tables);
// join by columns, with name
List<Pair<TableColumn, TableColumn>> p2list = this.getNameMatchedPairs(tables);
// FIXME whether we should add columns with different names
// but the same type? controlled by the flag of matchingNames.
if (p1list != null && !p1list.isEmpty()) {
for (Pair<TableColumn, TableColumn> p1 : p1list) {
skeleton.addJoinColumns(p1);
}
}
if (p2list != null && !p2list.isEmpty()) {
for (Pair<TableColumn, TableColumn> p2 : p2list) {
skeleton.addJoinColumns(p2);
}
}
// all projection columns
int index = 0;
for (TableColumn column : outputColumns) {
// the first column with the same name
TableColumn c = TableUtils.findFirstMatchedColumn(column.getColumnName(), this.inputTables);
if (c != null) {
skeleton.setProjectColumn(index, c);
}
index++;
}
return skeleton;
}