Backport #17249 to 20.12: Fix const column in set index.

src/Interpreters/Set.cpp

@@ -205,7 +205,7 @@ bool Set::insertFromBlock(const Block & block)
     {
         for (size_t i = 0; i < keys_size; ++i)
         {
-            auto filtered_column = block.getByPosition(i).column->filter(filter->getData(), rows);
+            auto filtered_column = key_columns[i]->filter(filter->getData(), rows);
             if (set_elements[i]->empty())
                 set_elements[i] = filtered_column;
             else

tests/queries/0_stateless/01583_const_column_in_set_index.reference

+3	5

tests/queries/0_stateless/01583_const_column_in_set_index.sql

+drop table if exists insub;
+
+create table insub (i int, j int) engine MergeTree order by i settings index_granularity = 1;
+insert into insub select number a, a + 2 from numbers(10);
+
+SET max_rows_to_read = 2;
+select * from insub where i in (select toInt32(3) from numbers(10));
+
+drop table if exists insub;