why delete will block by select? (2 replies)

hi ,all:
i am very confused about this deadlock,here is the detail info,why the delete will be blocked by select ?


*** (1) TRANSACTION:
TRANSACTION 657EBD98, ACTIVE 0 sec fetching rows
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1248, 12 row lock(s)
MySQL thread id 1563104, OS thread handle 0x4d8bb940, query id 304472500 192.168.2.169 opr updating
delete from phoenix_adspace_execution_byhour_oftime where createdTime >= str_to_date('2014-12-15 16', '%Y-%m-%d %H:%i:%s') and createdTime < str_to_date('2014-12-15 16','%Y-%m-%d %H:%i:%s') and ( adspaceId = 0 or adspaceId = 9681 or adspaceId = 9887......

*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 21133 page no 14 n bits 192 index "PRIMARY" of table "adxdb"."phoenix_adspace_execution_byhour_oftime" trx id 657EBD98 lock_mode X waiting
Record lock, heap no 84 PHYSICAL RECORD: n_fields 19; compact format; info bits 0


*** (2) TRANSACTION:
TRANSACTION 657EBD81, ACTIVE 0 sec starting index read, thread declared inside InnoDB 94
mysql tables in use 2, locked 2
8 lock struct(s), heap size 1248, 215 row lock(s)
MySQL thread id 1563101, OS thread handle 0x4e4eb940, query id 304472477 192.168.2.169 opr preparing
delete from phoenix_adspace_execution_byhour_ofregion where adspace_time_id in (select id from phoenix_adspace_execution_byhour_oftime where createdTime >= str_to_date('2014-12-15 16', '%Y-%m-%d %H:%i:%s') and createdTime < str_to_date('2014-12-15 16', '%Y-%m-%d %H:%i:%s') and ( adspaceId = 0 or adspaceId = 6841 or adspaceId = 8133
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 21133 page no 14 n bits 192 index "PRIMARY" of table "adxdb"."phoenix_adspace_execution_byhour_oftime" trx id 657EBD81 lock mode S locks rec but not gap
Record lock, heap no 84 PHYSICAL RECORD: n_fields 19; compact format; info bits 0

*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 21133 page no 14 n bits 192 index "PRIMARY" of table "adxdb"."phoenix_adspace_execution_byhour_oftime" trx id 657EBD81 lock mode S locks rec but not gap waiting
Record lock, heap no 72 PHYSICAL RECORD: n_fields 19; compact format; info bits 0