informix 表中目录尽然无效，强制索引也无效
set explain file to 'lf.out';
SELECT { +index (rc_sim.ind_sim_code) }
a.prod_inst_id PROD_INST_ATTR_ID ,
F_INF_IOM_CDMA_FLAG(a.order_item_id,a.prod_inst_id,0) ACTION_TYPE,
'C_IMSI' ATTR_CD,
'C_IMSI' ATTR_ID,
decode(b.imsi_id,null,'',to_char(b.imsi_id)) ATTR_VALUE_NEW,
F_INF_IOM_CDMA_OLD_INFO(a.order_item_id,a.prod_inst_id,0) ATTR_VALUE_OLD ,
a.comp_inst_id PARENT_PROD_INST_ATTR_ID
FROM (
select c.prod_inst_id,a.order_item_id,c.comp_inst_id ,c.col1
from order_item a,access_prod_inst c
WHERE a.order_item_id = 231204161205823
and a.order_item_obj_id = c.comp_inst_id
and c.prod_inst_id = 60135727306
) a left outer join rc_sim b
on a.col1 =b.resource_instance_code;
---几毫秒
select c.prod_inst_id,a.order_item_id,c.comp_inst_id ,c.col1
from order_item a,access_prod_inst c
WHERE a.order_item_id = 231204161205823
and a.order_item_obj_id = c.comp_inst_id
and c.prod_inst_id = 60135727306
--关联rc_sim（700万） 查询1分多钟
left outer join rc_sim
resource_instance_code 字段建有索引
请大侠指点！！！
------解决思路----------------------
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