private static String predicateToViewPredicate(F_PredicateInWhere pred, int viewIndex) {
String newName1 = pred.getTable1() + pred.getCol1() + "_" + viewIndex;
String newName2 = pred.getTable2() + pred.getCol2() + "_" + viewIndex;
if (pred.lhsIsConst()) {
newName1 = "'" + pred.getCol1() + "'";
} else if (pred.rhsIsConst()) {
newName2 = "'" + pred.getCol2() + "'";
}
return newName1 + pred.getOp() + newName2;
}
private static String createBackRule(
DBSchema baseSchema,
QueryFeature addedSnippet,
SymbolicDBView newView,
SymbolicDBView underlyingView,
int newViewIndex) {
StringBuilder backrule =
new StringBuilder(
"CREATE RULE R_"
+ newView.getViewName()
+ " AS \n"
+ "ON INSERT TO "
+ newView.getViewName()
+ " DO INSTEAD \n");
if (newViewIndex == 0) {
F_TableInFrom addedTable = (F_TableInFrom) addedSnippet;
backrule.append("INSERT INTO " + addedTable.getTableName() + " VALUES (");
// cols from newly added table
RelationSchema tableSchema = baseSchema.get(addedTable.getTableName());
for (ColumnSchema col : tableSchema.getAttributes()) {
backrule.append("NEW." + addedTable.getTableName() + col + "_" + newViewIndex + ",");
}
backrule.deleteCharAt(backrule.length() - 1); // remove last comma
backrule.append(");");
} else if (addedSnippet instanceof F_TableInFrom) {
F_TableInFrom addedTable = (F_TableInFrom) addedSnippet;
backrule.append("(INSERT INTO " + underlyingView.getViewName() + " VALUES (");
// cols from underlying view
for (String col : underlyingView.getColumnNames()) {
backrule.append("NEW." + oldColNameToNewColName(col, newViewIndex) + ",");
}
backrule.deleteCharAt(backrule.length() - 1); // remove last comma
backrule.append("); \nINSERT INTO " + addedTable.getTableName() + " VALUES(");
// cols from newly added table
RelationSchema tableSchema = baseSchema.get(addedTable.getTableName());
for (ColumnSchema col : tableSchema.getAttributes()) {
backrule.append("NEW." + addedTable.getTableName() + col + "_" + newViewIndex + ",");
}
backrule.deleteCharAt(backrule.length() - 1); // remove last comma
backrule.append("));");
} else if (addedSnippet instanceof F_PredicateInWhere) {
F_PredicateInWhere addedPred = (F_PredicateInWhere) addedSnippet;
backrule.append("(INSERT INTO " + underlyingView.getViewName() + " VALUES (");
// cols from underlying view
for (String col : newView.getColumnNames()) {
backrule.append("NEW." + col + ",");
}
backrule.deleteCharAt(backrule.length() - 1); // remove last comma
backrule.append(");");
// add constraint
if (addedPred.rhsIsConst()) {
backrule.append("\nINSERT INTO Constraints VALUES(");
backrule.append(
"NEW."
+ addedPred.getTable1()
+ addedPred.getCol1()
+ "_"
+ newViewIndex
+ ",'"
+ addedPred.getOp()
+ addedPred.getCol2()
+ "')");
} else if (addedPred.lhsIsConst()) {
backrule.append("\nINSERT INTO Constraints VALUES(");
backrule.append(
"NEW."
+ addedPred.getTable2()
+ addedPred.getCol2()
+ "_"
+ newViewIndex
+ ",'"
+ "reverse("
+ addedPred.getOp()
+ ")"
+ addedPred.getCol1()
+ "')");
} else {
backrule.append("\nINSERT INTO VarConstraints VALUES(");
backrule.append(
"NEW."
+ addedPred.getTable1()
+ addedPred.getCol1()
+ "_"
+ newViewIndex
+ ","
+ "NEW."
+ addedPred.getTable2()
+ addedPred.getCol2()
+ "_"
+ newViewIndex
+ ",'"
+ addedPred.getOp()
+ "')");
}
backrule.append("); ");
} else if (addedSnippet instanceof F_ColumnInSelect) {
// direct backrule. since we ignore projects.
backrule.append("INSERT INTO " + underlyingView.getViewName() + " VALUES (");
// cols from underlying view
for (String col : underlyingView.getColumnNames()) {
backrule.append("NEW." + oldColNameToNewColName(col, newViewIndex) + ",");
}
backrule.deleteCharAt(backrule.length() - 1); // remove last comma
backrule.append(");");
}
// problem: grouped by col1 [v1], and then we add col2 to the grouping[v2].
// v2 can not be computed from v1.
return backrule.toString();
}