Fix for BUG#8371: wrong rec_per_key value for hash index on temporary table

mysql-test/r/heap_hash.result

@@ -355,3 +355,13 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	heap_idx	heap_idx	20	const	7	Using where
 1	SIMPLE	t3	ref	a	a	40	func,const	6	Using where
 drop table t1, t2, t3;
+create temporary table t1 ( a int, index (a) ) engine=memory;
+insert into t1 values (1),(2),(3),(4),(5);
+select a from t1 where a in (1,3);
+a
+1
+3
+explain select a from t1 where a in (1,3);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	a	a	5	NULL	2	Using where
+drop table t1;

mysql-test/t/heap_hash.test

@@ -251,3 +251,9 @@ explain select * from t1 ignore key(btree_idx), t3 where t1.name='matt' and t3.a
 
 drop table t1, t2, t3;
 
+# Fix for BUG#8371: wrong rec_per_key value for hash index on temporary table
+create temporary table t1 ( a int, index (a) ) engine=memory;
+insert into t1 values (1),(2),(3),(4),(5);
+select a from t1 where a in (1,3);
+explain select a from t1 where a in (1,3);
+drop table t1;

sql/ha_heap.cc

@@ -60,7 +60,6 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
   {
     /* Initialize variables for the opened table */
     set_keys_for_scanning();
-    if (table->tmp_table == NO_TMP_TABLE)
     update_key_stats();
   }
   return (file ? 0 : 1);
@@ -103,6 +102,8 @@ void ha_heap::update_key_stats()
   for (uint i= 0; i < table->keys; i++)
   {
     KEY *key=table->key_info+i;
+    if (!key->rec_per_key)
+      continue;
     if (key->algorithm != HA_KEY_ALG_BTREE)
     {
       ha_rows hash_buckets= file->s->keydef[i].hash_buckets;
@@ -122,8 +123,8 @@ int ha_heap::write_row(byte * buf)
   if (table->next_number_field && buf == table->record[0])
     update_auto_increment();
   res= heap_write(file,buf);
-  if (!res && table->tmp_table == NO_TMP_TABLE && 
-      ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > file->s->records)
+  if (!res && ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > 
+              file->s->records)
     update_key_stats();
   return res;
 }
@@ -135,8 +136,8 @@ int ha_heap::update_row(const byte * old_data, byte * new_data)
   if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_UPDATE)
     table->timestamp_field->set_time();
   res= heap_update(file,old_data,new_data);
-  if (!res && table->tmp_table == NO_TMP_TABLE && 
-      ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > file->s->records)
+  if (!res && ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > 
+              file->s->records)
     update_key_stats();
   return res;
 }

sql/sql_select.cc

@@ -5289,6 +5289,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     keyinfo->key_length=(uint16) reclength;
     keyinfo->name=(char*) "tmp";
     keyinfo->algorithm= HA_KEY_ALG_UNDEF;
+    keyinfo->rec_per_key=0;
     if (null_pack_length)
     {
       key_part_info->null_bit=0;