fix(router): pass SET ... FROM CURRENT through to the server

pgdog/src/frontend/router/parser/query/set.rs

@@ -16,8 +16,8 @@ impl QueryParser {
     ) -> Result<Command, Error> {
         if stmt.kind == VAR_RESET_ALL {
             Ok(Command::ResetAll)
-        } else if stmt.kind == VAR_SET_MULTI {
-            // SET TRANSACTION
+        } else if stmt.kind == VAR_SET_MULTI || stmt.kind == VAR_SET_CURRENT {
+            // SET TRANSACTION, or SET ... FROM CURRENT which doesn't change the value.
             Ok(Command::Query(
                 Route::write(context.shards_calculator.shard().clone())
                     .with_read(context.read_only),

pgdog/src/frontend/router/parser/query/test/test_set.rs

@@ -312,3 +312,19 @@ fn test_single_shard_set() {
         _ => panic!("not a set"),
     }
 }
+
+#[test]
+fn test_set_from_current_passthrough() {
+    let mut test = QueryParserTest::new();
+
+    let command = test.execute(vec![Query::new("SET work_mem FROM CURRENT").into()]);
+    assert!(
+        matches!(command, Command::Query(_)),
+        "expected Command::Query, got {command:#?}",
+    );
+
+    let command = test.execute(vec![
+        Query::new("SET statement_timeout TO 1; SET work_mem FROM CURRENT").into(),
+    ]);
+    assert!(matches!(command, Command::Split(queries) if queries.len() == 2));
+}