Bug#34529: Crash on complex Falcon I_S select after ALTER .. PARTITION BY

  
When swapping out heap I_S tables to disk, this is done after plan refinement.
Thus, READ_RECORD::file will still point to the (deleted) heap handler at start
of execution. This causes segmentation fault if join buffering is used and the 
query is a star query where the result is found to be empty before accessing
some table. In this case that table has not been initialized (i.e. had its 
READ_RECORD re-initialized) before the cleanup routine tries to close the handler.
Fixed by updating READ_RECORD::file when changing handler.

mysql-test/r/information_schema.result

@@ -1422,3 +1422,13 @@ show fields from information_schema.table_names;
 ERROR 42S02: Unknown table 'table_names' in information_schema
 show keys from information_schema.table_names;
 ERROR 42S02: Unknown table 'table_names' in information_schema
+USE information_schema;
+SET max_heap_table_size = 16384;
+CREATE TABLE test.t1( a INT );
+SELECT *
+FROM tables ta
+JOIN collations co ON ( co.collation_name = ta.table_catalog )
+JOIN character_sets cs ON ( cs.character_set_name = ta.table_catalog );
+TABLE_CATALOG	TABLE_SCHEMA	TABLE_NAME	TABLE_TYPE	ENGINE	VERSION	ROW_FORMAT	TABLE_ROWS	AVG_ROW_LENGTH	DATA_LENGTH	MAX_DATA_LENGTH	INDEX_LENGTH	DATA_FREE	AUTO_INCREMENT	CREATE_TIME	UPDATE_TIME	CHECK_TIME	TABLE_COLLATION	CHECKSUM	CREATE_OPTIONS	TABLE_COMMENT	COLLATION_NAME	CHARACTER_SET_NAME	ID	IS_DEFAULT	IS_COMPILED	SORTLEN	CHARACTER_SET_NAME	DEFAULT_COLLATE_NAME	DESCRIPTION	MAXLEN
+DROP TABLE test.t1;
+SET max_heap_table_size = DEFAULT;

mysql-test/t/information_schema.test

@@ -1118,3 +1118,24 @@ show fields from information_schema.table_names;
 --error 1109
 show keys from information_schema.table_names;
 
+#
+# Bug#34529: Crash on complex Falcon I_S select after ALTER .. PARTITION BY
+#
+USE information_schema;
+SET max_heap_table_size = 16384;
+
+CREATE TABLE test.t1( a INT );
+
+# What we need to create here is a bit of a corner case:
+# We need a star query with information_schema tables, where the first
+# branch of the star join produces zero rows, so that reading of the 
+# second branch never happens. At the same time we have to make sure
+# that data for at least the last table is swapped from MEMORY/HEAP to 
+# MyISAM. This and only this triggers the bug.
+SELECT *
+FROM tables ta
+JOIN collations co ON ( co.collation_name = ta.table_catalog )
+JOIN character_sets cs ON ( cs.character_set_name = ta.table_catalog );
+
+DROP TABLE test.t1;
+SET max_heap_table_size = DEFAULT;

sql/sql_show.cc

@@ -4073,9 +4073,11 @@ bool get_schema_tables_result(JOIN *join,
       {
         result= 1;
         join->error= 1;
+        tab->read_record.file= table_list->table->file;
         table_list->schema_table_state= executed_place;
         break;
       }
+      tab->read_record.file= table_list->table->file;
       table_list->schema_table_state= executed_place;
     }
   }