PostgreSQL: forbid unsupported numeric types (#341)

Author: vitalyisaev2

app/server/datasource/interface.go

@@ -62,7 +62,7 @@ type ColumnDescription struct {
 	Name      string // mandatory
 	Type      string // mandatory
 	Precision *uint8 // filled only for numeric columns
-	Scale     *uint8 // filled only for numeric columns
+	Scale     *int8  // filled only for numeric columns
 }
 
 type TypeMapper interface {

app/server/datasource/rdbms/clickhouse/table_metadata_query.go

@@ -6,7 +6,8 @@ import (
 )
 
 func TableMetadataQuery(request *api_service_protos.TDescribeTableRequest) (string, *rdbms_utils.QueryArgs) {
-	query := "SELECT name, type, numeric_precision, numeric_scale FROM system.columns WHERE table = ? and database = ?"
+	query := `SELECT name, type, numeric_precision, toInt64(numeric_scale) 
+			FROM system.columns WHERE table = ? and database = ?`
 
 	var args rdbms_utils.QueryArgs
 

app/server/datasource/rdbms/postgresql/type_mapping.go

@@ -115,8 +115,20 @@ func (typeMapper) maybeNumericType(columnDescription *datasource.ColumnDescripti
 		return nil, nil
 	}
 
-	if columnDescription.Precision == nil || columnDescription.Scale == nil {
-		return nil, fmt.Errorf("for numeric type both precision and scale must be filled")
+	if columnDescription.Precision == nil {
+		return nil, fmt.Errorf("unconstrained numeric types with arbitrary precision are not supported")
+	}
+
+	if *columnDescription.Precision > 35 {
+		return nil, fmt.Errorf("precision of a numeric type must be less or equal to 35")
+	}
+
+	if columnDescription.Scale == nil {
+		return nil, fmt.Errorf("scale must be specified for numeric types")
+	}
+
+	if *columnDescription.Scale < 0 {
+		return nil, fmt.Errorf("scale must be non-negative")
 	}
 
 	return common.MakeDecimalType(uint32(*columnDescription.Precision), uint32(*columnDescription.Scale)), nil

app/server/datasource/rdbms/utils/schema_provider.go

@@ -40,37 +40,37 @@ func (f *defaultSchemaProvider) GetSchema(
 
 	defer func() { common.LogCloserError(logger, rows, "close rows") }()
 
-	var cd datasource.ColumnDescription
-
 	sb := NewSchemaBuilder(f.typeMapper, request.TypeMappingSettings)
 
 	var (
 		columnName *string
 		typeName   *string
 		precision  *uint64
-		scale      *uint64
+		scale      *int64
 	)
 
 	for rows.Next() {
 		if err = rows.Scan(&columnName, &typeName, &precision, &scale); err != nil {
 			return nil, fmt.Errorf("rows scan: %w", err)
 		}
 
-		cd.Name = *columnName
-		cd.Type = *typeName
+		cd := &datasource.ColumnDescription{
+			Name: *columnName,
+			Type: *typeName,
+		}
 
 		if precision != nil {
 			cd.Precision = new(uint8)
 			*cd.Precision = uint8(*precision)
 		}
 
 		if scale != nil {
-			cd.Scale = new(uint8)
-			*cd.Scale = uint8(*scale)
+			cd.Scale = new(int8)
+			*cd.Scale = int8(*scale)
 		}
 
-		if err = sb.AddColumn(&cd); err != nil {
-			return nil, fmt.Errorf("add column to schema builder: %w", err)
+		if err = sb.AddColumn(cd); err != nil {
+			return nil, fmt.Errorf("add column `%s` to schema builder: %w", cd.Name, err)
 		}
 	}
 

scripts/debug/kqprun/script.postgresql.local.txt

@@ -6,3 +6,4 @@ SELECT col_27_numeric_int, col_28_numeric_rational FROM external_datasource.prim
 
 -- SELECT col_27_numeric_int, col_28_numeric_rational FROM external_datasource.primitives WHERE col_28_numeric_rational = Decimal("-22.22", 4, 2);
 
+