做了索引仍走全表扫描!!!!

sainker

select tracedata0_.PROJECT_ID as col_0_0_, count(*) as col_1_0_ from TRACE_DATA tracedata0_ where 1=1 group by tracedata0_.PROJECT_ID
PROJECT_ID做索引，有人知道吗？

sainker

Plan hash value: 1035345316

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| Id  | Operation           | Name        | Rows        | Bytes | Cost (%CPU)| Time
|

--------------------------------------------------------------------------------
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|   0 | SELECT STATEMENT   |                |    60 |   240 |   196K  (1)| 00:39:15
|

|   1 |  HASH GROUP BY           |                |    60 |   240 |   196K  (1)| 00:39:15
|

|   2 |   TABLE ACCESS FULL| TRACE_DATA |    11M|    43M|   195K  (1)| 00:39:10
|

--------------------------------------------------------------------------------
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统计信息
----------------------------------------------------------
          0  recursive calls
          0  db block gets
     803674  consistent gets
     803448  physical reads
          0  redo size
       1916  bytes sent via SQL*Net to client
        564  bytes received via SQL*Net from client
          6  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         61  rows processed

renxiao2003

不太明白。弄个where 1=1干什么？

拿钱发帖死全家

你这个肯定要走全表扫描了，看你的条件

jiangxiaoyu

关键是 为什么要 count(*)  呢？