public QuerySessionWithViews(QuerySession underlyingQuerySession) {
this.underlyingQuerySession = underlyingQuerySession;
this.correspondingViews = new ArrayList<SymbolicDBView>();
for (int i = 0; i < underlyingQuerySession.numSteps(); i++) {
List<QueryFeature> step = underlyingQuerySession.getSteps().get(i);
assert (step.size() == 1);
StringBuilder viewDefinition = new StringBuilder("CREATE VIEW V" + i + " AS \nSELECT ");
List<String> viewColumns = new ArrayList<String>();
QueryFeature addedSnippet = step.get(0);
if (i == 0) {
F_TableInFrom table = (F_TableInFrom) addedSnippet;
RelationSchema tableSchema = underlyingQuerySession.getSchema().get(table.getTableName());
for (ColumnSchema col : tableSchema.getAttributes()) {
String fullColName = tableSchema.getRelationName() + "." + col;
viewDefinition.append(
fullColName + " AS " + fullColName.replace(".", "") + "_" + i + ",");
viewColumns.add(fullColName.replace(".", "") + "_" + i);
}
viewDefinition.deleteCharAt(viewDefinition.length() - 1); // remove last comma
viewDefinition.append("\nFROM " + table.getTableName() + ";");
} else if (addedSnippet instanceof F_TableInFrom) {
F_TableInFrom addedTable = (F_TableInFrom) addedSnippet;
RelationSchema tableSchema =
underlyingQuerySession.getSchema().get(addedTable.getTableName());
// columns from V_i-1
for (String oldColName : correspondingViews.get(i - 1).columnNames) {
viewDefinition.append(oldColName + " AS " + oldColNameToNewColName(oldColName, i) + ",");
viewColumns.add(oldColNameToNewColName(oldColName, i));
}
// columns from addedTable
for (ColumnSchema col : tableSchema.getAttributes()) {
String fullColName = tableSchema.getRelationName() + "." + col;
viewDefinition.append(
fullColName + " AS " + fullColName.replace(".", "") + "_" + i + ",");
viewColumns.add(fullColName.replace(".", "") + "_" + i);
}
viewDefinition.deleteCharAt(viewDefinition.length() - 1); // remove last comma
viewDefinition.append("\nFROM V" + (i - 1) + "," + addedTable.getTableName() + ";");
} else if (addedSnippet instanceof F_PredicateInWhere) {
F_PredicateInWhere addedPred = (F_PredicateInWhere) addedSnippet;
// columns from V_i-1
for (String oldColName : correspondingViews.get(i - 1).columnNames) {
viewDefinition.append(oldColName + " AS " + oldColNameToNewColName(oldColName, i) + ",");
viewColumns.add(oldColNameToNewColName(oldColName, i));
}
viewDefinition.deleteCharAt(viewDefinition.length() - 1); // remove last comma
viewDefinition.append("\nFROM V" + (i - 1));
viewDefinition.append("\nWHERE " + predicateToViewPredicate(addedPred, (i - 1)) + ";");
} else if (addedSnippet instanceof F_ColumnInGroupBy) {
F_ColumnInGroupBy addedGroupbyCol = (F_ColumnInGroupBy) addedSnippet;
viewDefinition.append(
colNameToViewColName(
addedGroupbyCol.getTableName(), addedGroupbyCol.getColumnName(), i - 1)
+ " AS "
+ colNameToViewColName(
addedGroupbyCol.getTableName(), addedGroupbyCol.getColumnName(), i));
viewDefinition.append(", count(*)");
viewDefinition.append("\nFROM V" + (i - 1));
viewDefinition.append(
"\nGROUP BY "
+ colNameToViewColName(
addedGroupbyCol.getTableName(), addedGroupbyCol.getColumnName(), i - 1));
viewColumns.add(
colNameToViewColName(
addedGroupbyCol.getTableName(), addedGroupbyCol.getColumnName(), i));
}
SymbolicDBView sv = new SymbolicDBView("V" + i, viewDefinition.toString(), viewColumns);
if (i > 0) {
sv.setBackRule(
createBackRule(
underlyingQuerySession.getSchema(),
addedSnippet,
sv,
correspondingViews.get(i - 1),
i));
} else {
sv.setBackRule(
createBackRule(underlyingQuerySession.getSchema(), addedSnippet, sv, null, i));
}
correspondingViews.add(sv);
}
}
