Include columns in show output

core/dbt/events/core_types.proto

@@ -1532,6 +1532,7 @@ message ShowNode {
     bool is_inline = 3;
     string output_format = 4;
     string unique_id = 5;
+    repeated string columns = 6;
 }
 
 message ShowNodeMsg {

core/dbt/events/types.py

@@ -1520,10 +1520,17 @@ class ShowNode(InfoLevel):
     def message(self) -> str:
         if self.output_format == "json":
             if self.is_inline:
-                return json.dumps({"show": json.loads(self.preview)}, indent=2)
+                return json.dumps(
+                    {"columns": list(self.columns), "show": json.loads(self.preview)}, indent=2
+                )
             else:
                 return json.dumps(
-                    {"node": self.node_name, "show": json.loads(self.preview)}, indent=2
+                    {
+                        "node": self.node_name,
+                        "columns": list(self.columns),
+                        "show": json.loads(self.preview),
+                    },
+                    indent=2,
                 )
         else:
             if self.is_inline:

core/dbt/task/show.py

@@ -101,6 +101,7 @@ class ShowTask(CompileTask):
             fire_event(
                 ShowNode(
                     node_name=node_name,
+                    columns=[col.name for col in table.columns],
                     preview=output.getvalue(),
                     is_inline=is_inline,
                     output_format=self.args.output,