[FEAT MERGE] Solidify session vars for functional index

src/sql/engine/expr/ob_expr_field.cpp

@@ -200,5 +200,12 @@ int ObExprField::eval_field(const ObExpr &expr, ObEvalCtx &ctx, ObDatum &expr_da
   return ret;
 }
 
+DEF_SET_LOCAL_SESSION_VARS(ObExprField, raw_expr) {
+  int ret = OB_SUCCESS;
+  SET_LOCAL_SYSVAR_CAPACITY(1);
+  EXPR_ADD_LOCAL_SYSVAR(share::SYS_VAR_COLLATION_CONNECTION);
+  return ret;
+}
+
 } // namespace sql
 } // namespace oceanbase