NHibernate +流畅的 NHibernate +甲骨文索引

发布于 2024-08-15 12:38:28 字数 753 浏览 7 评论 0原文

我有一个包含超过 10 000 000 行的表。在 TOAD 中，此查询运行得很好：

select /*+ INDEX(x IDX_CASHFLOW_COMPLEX)*/ * 
from MYPR.CASHFLOW x 
where fk_debet in (21856, 21854, 21855)

IDX_CASHFLOW_COMPLEX 是由以下脚本创建的 5 列索引：

CREATE INDEX MYPR.IDX_CASHFLOW_COMPLEX ON MYPR.CASHFLOW
(FK_DEBIT, FK_CREDIT, FK_DOCUMENT, PAYMENTDATE, FK_PAYMENTCODE)
LOGGING
TABLESPACE INDX
PCTFREE    10
INITRANS   2
MAXTRANS   255
STORAGE    (
            INITIAL          64K
            MINEXTENTS       1
            MAXEXTENTS       UNLIMITED
            PCTINCREASE      0
            BUFFER_POOL      DEFAULT
           )
NOPARALLEL;

类似的查询，但没有 Oracle 提示语法，运行速度明显慢！

您能否建议是否可以告诉 NHibernate 在查询中添加 Oracle 提示？

谢谢！

原文

I have a table with more than 10 000 000 rows.
In TOAD this query works very well on it:

select /*+ INDEX(x IDX_CASHFLOW_COMPLEX)*/ * 
from MYPR.CASHFLOW x 
where fk_debet in (21856, 21854, 21855)

IDX_CASHFLOW_COMPLEX is index on 5 columns created by following script:

CREATE INDEX MYPR.IDX_CASHFLOW_COMPLEX ON MYPR.CASHFLOW
(FK_DEBIT, FK_CREDIT, FK_DOCUMENT, PAYMENTDATE, FK_PAYMENTCODE)
LOGGING
TABLESPACE INDX
PCTFREE    10
INITRANS   2
MAXTRANS   255
STORAGE    (
            INITIAL          64K
            MINEXTENTS       1
            MAXEXTENTS       UNLIMITED
            PCTINCREASE      0
            BUFFER_POOL      DEFAULT
           )
NOPARALLEL;

Similar query but without Oracle hint syntax works significantly slower!

Would you please suggest is it possible to tell NHibernate to add Oracle hint in the query?

Thanks!

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温柔戏命师 2024-08-22 12:38:28

您的优化器统计信息是最新的吗？如果没有，您可能会发现一旦生成它们，您根本不需要提示。

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撑一把青伞 2024-08-22 12:38:28

据推测，没有提示的查询没有使用索引。

在任何 sql 工具中尝试此操作：

explain plan for
select /*+ INDEX(x IDX_CASHFLOW_COMPLEX)*/ * 
from MYPR.CASHFLOW x 
where fk_debet in (21856, 21854, 21855)
/

select * from table(dbms_xplan.display)
/

...并发布最后一个命令的输出。我们可以用它来查看 Oracle 对结果集的预期基数做出的估计。

Presumably the query without the hint is not using the index.

Try this in any sql tool:

explain plan for
select /*+ INDEX(x IDX_CASHFLOW_COMPLEX)*/ * 
from MYPR.CASHFLOW x 
where fk_debet in (21856, 21854, 21855)
/

select * from table(dbms_xplan.display)
/

... and post the output of the last command. We can use that to see what estimations oracle is making of the expected cardinality of the result set.

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财迷小姐 2024-08-22 12:38:28

有提示 /* +INDEX(...) */ :

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 238 | 26 |
| 1 | INLIST ITERATOR | | | | |
| 2 | TABLE ACCESS BY INDEX ROWID| CASHFLOW | 1 | 238 | 26 |
|* 3 | INDEX RANGE SCAN | IDX_CASHFLOW_COMPLEX | 1 | | 2 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - access("X"."FK_DEBIT"=21854 OR "X"."FK_DEBIT"=21855 OR "X"."FK_DEBIT"=21856)
Note: cpu costing is off

无提示 /* +INDEX(...) */ :

-------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
--------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 238 | 2 |
|* 1 | TABLE ACCESS FULL | CASHFLOW | 1 | 238 | 2 |
--------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("X"."FK_DEBIT"=21854 OR "X"."FK_DEBIT"=21855 OR "X"
."FK_DEBIT"=21856)
Note: cpu costing is off

With hint /* +INDEX(...) */ :

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 238 | 26 |
| 1 | INLIST ITERATOR | | | | |
| 2 | TABLE ACCESS BY INDEX ROWID| CASHFLOW | 1 | 238 | 26 |
|* 3 | INDEX RANGE SCAN | IDX_CASHFLOW_COMPLEX | 1 | | 2 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - access("X"."FK_DEBIT"=21854 OR "X"."FK_DEBIT"=21855 OR "X"."FK_DEBIT"=21856)
Note: cpu costing is off

Without hint /* +INDEX(...) */ :

-------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
--------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 238 | 2 |
|* 1 | TABLE ACCESS FULL | CASHFLOW | 1 | 238 | 2 |
--------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("X"."FK_DEBIT"=21854 OR "X"."FK_DEBIT"=21855 OR "X"
."FK_DEBIT"=21856)
Note: cpu costing is off

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