Revert "remove unnecessary function"

This reverts commit d710427.

Author: rayakame

internal/codegen/golang/postgresql_type.go

@@ -1,14 +1,39 @@
 package golang
 
 import (
+	"fmt"
 	"log"
+	"strings"
 
 	"github.com/sqlc-dev/sqlc/internal/codegen/golang/opts"
 	"github.com/sqlc-dev/sqlc/internal/codegen/sdk"
 	"github.com/sqlc-dev/sqlc/internal/debug"
 	"github.com/sqlc-dev/sqlc/internal/plugin"
 )
 
+func parseIdentifierString(name string) (*plugin.Identifier, error) {
+	parts := strings.Split(name, ".")
+	switch len(parts) {
+	case 1:
+		return &plugin.Identifier{
+			Name: parts[0],
+		}, nil
+	case 2:
+		return &plugin.Identifier{
+			Schema: parts[0],
+			Name:   parts[1],
+		}, nil
+	case 3:
+		return &plugin.Identifier{
+			Catalog: parts[0],
+			Schema:  parts[1],
+			Name:    parts[2],
+		}, nil
+	default:
+		return nil, fmt.Errorf("invalid name: %s", name)
+	}
+}
+
 func postgresType(req *plugin.GenerateRequest, options *opts.Options, col *plugin.Column) string {
 	columnType := sdk.DataType(col.Type)
 	notNull := col.NotNull || col.IsArray
@@ -530,7 +555,11 @@ func postgresType(req *plugin.GenerateRequest, options *opts.Options, col *plugi
 		return "interface{}"
 
 	default:
-		rel := col.Type
+		rel, err := parseIdentifierString(columnType)
+		if err != nil {
+			// TODO: Should this actually return an error here?
+			return "interface{}"
+		}
 		if rel.Schema == "" {
 			rel.Schema = req.Catalog.DefaultSchema
 		}