Allow RENAME of index columns.

src/Storages/MergeTree/MergeTreeData.cpp

@@ -3047,8 +3047,7 @@ void MergeTreeData::checkAlterIsPossible(const AlterCommands & commands, Context
                                 backQuoteIfNeed(command.column_name));
             }
 
-            /// Don't check columns in indices here. If required columns of indices get renamed, it
-            /// will be checked later in AlterCommands::apply.
+            /// Don't check columns in indices here. RENAME works fine with index columns.
 
             if (auto it = columns_in_projections.find(command.column_name); it != columns_in_projections.end())
             {

tests/queries/0_stateless/01213_alter_rename_primary_key_zookeeper_long.sql

@@ -52,6 +52,4 @@ ALTER TABLE table_for_rename_with_primary_key RENAME COLUMN key2 TO renamed_key2
 
 ALTER TABLE table_for_rename_with_primary_key RENAME COLUMN key3 TO renamed_key3; --{serverError 524}
 
-ALTER TABLE table_for_rename_with_primary_key RENAME COLUMN value1 TO renamed_value1; --{serverError 524}
-
 DROP TABLE IF EXISTS table_for_rename_with_primary_key;

tests/queries/0_stateless/02920_rename_column_of_skip_indices.sql

@@ -0,0 +1,31 @@
+DROP TABLE IF EXISTS t;
+
+CREATE TABLE t
+(
+  key1 UInt64,
+  value1 String,
+  value2 String,
+  INDEX idx (value1) TYPE set(10) GRANULARITY 1
+)
+ENGINE MergeTree ORDER BY key1 SETTINGS index_granularity = 1;
+
+INSERT INTO t SELECT toDate('2019-10-01') + number % 3, toString(number), toString(number) from numbers(9);
+
+SYSTEM STOP MERGES t;
+
+SET alter_sync = 0;
+
+ALTER TABLE t RENAME COLUMN value1 TO value11;
+
+-- Index works without mutation applied.
+SELECT * FROM t WHERE value11 = '000' SETTINGS max_rows_to_read = 0;
+
+SYSTEM START MERGES t;
+
+-- Another ALTER to wait for.
+ALTER TABLE t RENAME COLUMN value11 TO value12 SETTINGS mutations_sync = 2;
+
+-- Index works with mutation applied.
+SELECT * FROM t WHERE value12 = '000' SETTINGS max_rows_to_read = 0;
+
+DROP TABLE t;