Support check constraint backend (GoogleCloudPlatform#962)

* Check constraint backend (#9)

Backend Support for Check Constraint

* update api

* fix PR comment

* remove api call to while validating constraints

* Fixed db collation regex to remove collation name from the results

* renamed function name to formatCheckConstraints and added check if constraint name is empty

* fixed PR comments

* added test case for the empty check constraint name

* fix: added regular exprression to match the exact column

* fix: added regular expression to replace table name

* Added test case for the column rename for check constraint

* 1. Refactored GetConstraint function
2. Fixed inforschema unit tests

* added comment at handling case for check constraints

* reverted white spaces

* reverted white spaces

* nit: doesCheckConstraintNameExist

* added comments for doesCheckConstraintNameExist

* PR and UT fixes

* fix UT

* UT fix

* Removed isCheckConstraintsTablePresent function

* moved regex globally

* Fix UT

* fixed UT

* fixed handling of the constraints

* removed unused function

* added unit tests for incompatable name

* Combined unit tests

* added test case for the renaming column having substring of other column

* added the query changes which return distinct value

---------

Co-authored-by: taherkl <taher.lakdawala@ollion.com>
Co-authored-by: Akash Thawait <aakash@ollion.com>
Co-authored-by: Vivek Yadav <vivek.yadav@ollion.com>

sources/common/toddl.go

@@ -294,7 +294,6 @@ func (ss *SchemaToSpannerImpl) SchemaToSpannerDDLHelper(conv *internal.Conv, tod
 		Comment:          comment,
 		Id:               srcTable.Id,
 	}
-
 	return nil
 }
 
@@ -360,9 +359,10 @@ func cvtCheckConstraint(conv *internal.Conv, srcKeys []schema.CheckConstraint) [
 
 	for _, cc := range srcKeys {
 		spcc = append(spcc, ddl.CheckConstraint{
-			Id:   cc.Id,
-			Name: internal.ToSpannerCheckConstraintName(conv, cc.Name),
-			Expr: cc.Expr,
+			Id:     cc.Id,
+			Name:   internal.ToSpannerCheckConstraintName(conv, cc.Name),
+			Expr:   cc.Expr,
+			ExprId: cc.ExprId,
 		})
 	}
 	return spcc

sources/common/toddl_test.go

@@ -434,14 +434,22 @@ func Test_cvtCheckContraint(t *testing.T) {
 	conv := internal.MakeConv()
 	srcSchema := []schema.CheckConstraint{
 		{
-			Id:   "cc1",
-			Name: "check_1",
-			Expr: "age > 0",
+			Id:     "cc1",
+			Name:   "check_1",
+			Expr:   "age > 0",
+			ExprId: "expr1",
 		},
 		{
-			Id:   "cc2",
-			Name: "check_2",
-			Expr: "age < 99",
+			Id:     "cc2",
+			Name:   "check_2",
+			Expr:   "age < 99",
+			ExprId: "expr2",
+		},
+		{
+			Id:     "cc3",
+			Name:   "@invalid_name", // incompatabile name
+			Expr:   "age != 0",
+			ExprId: "expr3",
 		},
 		{
 			Id:   "cc3",
@@ -451,14 +459,22 @@ func Test_cvtCheckContraint(t *testing.T) {
 	}
 	spSchema := []ddl.CheckConstraint{
 		{
-			Id:   "cc1",
-			Name: "check_1",
-			Expr: "age > 0",
+			Id:     "cc1",
+			Name:   "check_1",
+			Expr:   "age > 0",
+			ExprId: "expr1",
+		},
+		{
+			Id:     "cc2",
+			Name:   "check_2",
+			Expr:   "age < 99",
+			ExprId: "expr2",
 		},
 		{
-			Id:   "cc2",
-			Name: "check_2",
-			Expr: "age < 99",
+			Id:     "cc3",
+			Name:   "Ainvalid_name",
+			Expr:   "age != 0",
+			ExprId: "expr3",
 		},
 		{
 			Id:   "cc3",

sources/mysql/infoschema.go

@@ -337,7 +337,7 @@ func (isi InfoSchemaImpl) processRow(
 	// Case added to handle check constraints
 	case "CHECK":
 		checkClause = collationRegex.ReplaceAllString(checkClause, "")
-		*checkKeys = append(*checkKeys, schema.CheckConstraint{Name: constraintName, Expr: checkClause, Id: internal.GenerateCheckConstrainstId()})
+		*checkKeys = append(*checkKeys, schema.CheckConstraint{Name: constraintName, Expr: checkClause, ExprId: internal.GenerateCheckConstrainstExprId(), Id: internal.GenerateCheckConstrainstId()})
 	default:
 		m[col] = append(m[col], constraintType)
 	}

webv2/api/schema.go

@@ -531,6 +531,7 @@ func UpdateCheckConstraint(w http.ResponseWriter, r *http.Request) {
 	json.NewEncoder(w).Encode(convm)
 }
 
+// findColId based on constraint condition it will return colId.
 func findColId(colDefs map[string]ddl.ColumnDef, condition string) string {
 	for _, colDef := range colDefs {
 		if strings.Contains(condition, colDef.Name) {