fix reading of unneded column in case of multistage prewhere

src/Storages/MergeTree/MergeTreeBlockReadUtils.cpp

@@ -340,8 +340,10 @@ MergeTreeReadTaskColumns getReadTaskColumns(
             if (!columns_from_previous_steps.contains(name))
                 step_column_names.push_back(name);
 
-        injectRequiredColumns(
-            data_part_info_for_reader, storage_snapshot, with_subcolumns, step_column_names);
+        if (!step_column_names.empty())
+            injectRequiredColumns(
+                data_part_info_for_reader, storage_snapshot,
+                with_subcolumns, step_column_names);
 
         /// More columns could have been added, filter them as well by the list of columns from previous steps.
         Names columns_to_read_in_step;

tests/queries/0_stateless/02833_multiprewhere_extra_column.reference

@@ -0,0 +1,2 @@
+10496500
+4

tests/queries/0_stateless/02833_multiprewhere_extra_column.sql

@@ -0,0 +1,25 @@
+-- Tags: no-parallel, no-random-settings, no-random-merge-tree-settings
+
+drop table if exists t_multi_prewhere;
+drop row policy if exists policy_02834 on t_multi_prewhere;
+
+create table t_multi_prewhere (a UInt64, b UInt64, c UInt8)
+engine = MergeTree order by tuple()
+settings min_bytes_for_wide_part = 0;
+
+create row policy policy_02834 on t_multi_prewhere using a > 2000 as permissive to all;
+insert into t_multi_prewhere select number, number, number from numbers(10000);
+
+system drop mark cache;
+select sum(b) from t_multi_prewhere prewhere a < 5000;
+
+system flush logs;
+
+select ProfileEvents['FileOpen'] from system.query_log
+where
+    type = 'QueryFinish'
+    and current_database = currentDatabase()
+    and query ilike '%select sum(b) from t_multi_prewhere prewhere a < 5000%';
+
+drop table if exists t_multi_prewhere;
+drop row policy if exists policy_02834 on t_multi_prewhere;