Oracle SQL-為什么此查詢具有全表掃描？

Question

我對此查詢有疑問：

SELECT *
  FROM customer_table PARTITION (p25062014)
 WHERE (   customer_table.username NOT IN ('user1','user2','user3')
        OR customer_table.username IS NULL
       )
   AND (customer_table.ip NOT IN ('ip1','ip2','ip3') OR customer_table.ip IS NULL
       )
   AND (   customer_table."ACCOUNT DEVICE ID" NOT IN ('deviceId1','deviceId2','deviceId3')
        OR customer_table."ACCOUNT DEVICE ID" IS NULL
       )

即使我已經在這些表上為這些字段創建了索引，我在表上仍然有一個“表訪問已滿”：

CREATE INDEX customer_table_USERNAME ON customer_table
(USERNAME)

CREATE INDEX customer_table_DEVICE_ID ON customer_table
("ACCOUNT DEVICE ID")

CREATE INDEX customer_table_IP ON customer_table
(IP)

Plan
SELECT STATEMENT  ALL_ROWSCost: 2  Bytes: 965  Cardinality: 1       
    2 PARTITION RANGE SINGLE  Cost: 2  Bytes: 965  Cardinality: 1  Partition #: 1  Partitions accessed #21  
        1 TABLE ACCESS FULL TABLE customer_table Cost: 2  Bytes: 965  Cardinality: 1  Partition #: 2  Partitions accessed #21

我該如何解決？ 謝謝。

Answer 1

NOT IN where子句通常不使用索引，因為從索引中獲得的收益不多。 在此處閱讀詳細信息。 盡管該博客解釋了為什么對“非等式”比較而言索引被忽略，但對NOT IN也是有效的。