BUG#30583 - Partition on DOUBLE key + INNODB + count(*) == crash

Issuing SELECT COUNT(*) against partitioned InnoDB table may cause
server crash.

Fixed that not all required fields were included into read_set.

mysql-test/r/partition_innodb.result

@@ -129,3 +129,10 @@ insert into t1 (time, first_name, last_name) values ('2007-02-07', 'Q', 'Robert'
 SELECT * FROM t1 WHERE first_name='Andy' OR last_name='Jake';
 id	time	first_name	last_name
 drop table t1;
+CREATE TABLE t1 (a DOUBLE NOT NULL, KEY(a)) ENGINE=InnoDB
+PARTITION BY KEY(a) PARTITIONS 10;
+INSERT INTO t1 VALUES(1),(2);
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+2
+DROP TABLE t1;

mysql-test/t/partition_innodb.test

@@ -134,3 +134,11 @@ SELECT * FROM t1 WHERE first_name='Andy' OR last_name='Jake';
 
 drop table t1;
 
+#
+# BUG#30583 - Partition on DOUBLE key + INNODB + count(*) == crash
+#
+CREATE TABLE t1 (a DOUBLE NOT NULL, KEY(a)) ENGINE=InnoDB
+PARTITION BY KEY(a) PARTITIONS 10;
+INSERT INTO t1 VALUES(1),(2);
+SELECT COUNT(*) FROM t1;
+DROP TABLE t1;

sql/ha_partition.cc

@@ -3324,6 +3324,22 @@ int ha_partition::index_init(uint inx, bool sorted)
   */
   if (m_lock_type == F_WRLCK)
     bitmap_union(table->read_set, &m_part_info->full_part_field_set);
+  else if (sorted && m_table_flags & HA_PARTIAL_COLUMN_READ)
+  {
+    /*
+      An ordered scan is requested and necessary fields aren't in read_set.
+      This may happen e.g. with SELECT COUNT(*) FROM t1. We must ensure
+      that all fields of current key are included into read_set, as
+      partitioning requires them for sorting
+      (see ha_partition::handle_ordered_index_scan).
+
+      TODO: handle COUNT(*) queries via unordered scan.
+    */
+    uint i;
+    for (i= 0; i < m_curr_key_info->key_parts; i++)
+      bitmap_set_bit(table->read_set,
+                     m_curr_key_info->key_part[i].field->field_index);
+  }
   file= m_file;
   do
   {