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【学习笔记】Oracle 11G新特性query result cache(3)深入研究笔记

时间:2016-11-18 23:02   来源:Oracle研究中心   作者:网络   点击:

天萃荷净 Oracle研究中心学习笔记:分享一篇关于Oracle数据库11G新特性研究的笔记,详细介绍query result cache特性的使用案例。

本站文章除注明转载外,均为本站原创: 转载自love wife & love life —Roger 的Oracle技术博客
本文链接地址: 11g 新特性之–query result cache(3)

11gR2中,query cache的特别之处,详见下面的实验。

SQL> SHOW USER
USER IS "ROGER"

SQL> CREATE TABLE ht03 AS SELECT * FROM ht02 WHERE rownum <10000;

TABLE created.
Elapsed: 00:00:03.51

SQL> DESC ht03

Name                                      NULL     TYPE
----------------------------------------- -------- ----------------------------
OWNER                                              VARCHAR2(30)
OBJECT_ID                                          NUMBER
OBJECT_NAME                                        VARCHAR2(128)

SQL> CREATE TABLE ht04(
  2    OWNER VARCHAR2(30),
  3    OBJECT_ID NUMBER,
  4    OBJECT_NAME VARCHAR2(128)
  5  ) RESULT_CACHE (MODE FORCE);

TABLE created.
Elapsed: 00:00:00.14

SQL> INSERT INTO /*+append */ ht04  SELECT * FROM ht03;

9999 ROWS created.
Elapsed: 00:00:00.32

SQL> commit;
Commit complete.
Elapsed: 00:00:00.01

SQL> CREATE INDEX ht03_idx ON ht03(object_id);
INDEX created.
Elapsed: 00:00:00.32

SQL>  CREATE INDEX ht04_idx ON ht04(object_id);
INDEX created.
Elapsed: 00:00:00.10

SQL> analyze TABLE ht03 compute statistics FOR TABLE FOR ALL indexes FOR ALL indexed COLUMNS;
TABLE analyzed.
Elapsed: 00:00:00.73

SQL> analyze TABLE ht04 compute statistics FOR TABLE FOR ALL indexes FOR ALL indexed COLUMNS;
TABLE analyzed.
Elapsed: 00:00:00.18

SQL> SET autot traceonly
SQL> SET LINES 160
SQL> SELECT * FROM ht03 WHERE object_id=999;

Elapsed: 00:00:00.02
Execution Plan
----------------------------------------------------------
Plan hash VALUE: 1330547204

----------------------------------------------------------------------------------------
| Id  | Operation                   | Name     | ROWS  | Bytes | Cost (%CPU)| TIME     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |          |     1 |    36 |     2   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| HT03     |     1 |    36 |     2   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | HT03_IDX |     1 |       |     1   (0)| 00:00:01 |
----------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   2 - access("OBJECT_ID"=999)

Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo SIZE
        570  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> SELECT * FROM ht04 WHERE object_id=999;

Elapsed: 00:00:00.02

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2782040647

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    36 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | 1wsv07hr29687c877123g0cumt |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT04                       |     1 |    36 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | HT04_IDX                   |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=999)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT04); attributes=(ordered); name="select * from ht04 where object_id=999"

Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo SIZE
        566  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> SHOW parameter RESULT

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
_client_result_cache_bypass          BOOLEAN     FALSE
_result_cache_auto_execution_thresho INTEGER     1
ld
_result_cache_auto_size_threshold    INTEGER     100
_result_cache_auto_time_distance     INTEGER     300
_result_cache_auto_time_threshold    INTEGER     1000
_result_cache_block_size             INTEGER     1024
_result_cache_global                 BOOLEAN     TRUE
_result_cache_timeout                INTEGER     10
_xsolapi_sql_result_set_cache_size   INTEGER     32
client_result_cache_lag              big INTEGER 3000
client_result_cache_size             big INTEGER 0
result_cache_max_result              INTEGER     5
result_cache_max_size                big INTEGER 960K
result_cache_mode                    string      MANUAL
result_cache_remote_expiration       INTEGER     0

SQL> SELECT /*+ RESULT_CACHE */ * FROM ht03 WHERE object_id=999;

Elapsed: 00:00:00.02

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 1330547204

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    36 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | f42hd8bp1h26hbdqqs6bz47m3z |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT03                       |     1 |    36 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | HT03_IDX                   |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=999)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT03); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht03 where object_id=999"

Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo SIZE
        566  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed
从上面的实验,我们可以看出11gR2 比11gR1 多了其中一点就是这里,那就是在create table的时候,
我们可以指定是否对该表启用query cache特性,create table的语法如下:

CREATE|ALTER TABLE [<schema>.]<table> ... [RESULT_CACHE (MODE {FORCE|DEFAULT})]
当然,既然create table有了新的语法,那么必然同时也会增加alter table的语法了,请看测试。

SQL> SET autot off
SQL> ALTER TABLE ht03 RESULT_CACHE(mode force);

TABLE altered.
Elapsed: 00:00:00.33

SQL> SET autot traceonly
SQL> SELECT * FROM ht03 WHERE object_id=999;

Elapsed: 00:00:00.05

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 1330547204

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    36 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | f42hd8bp1h26hbdqqs6bz47m3z |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT03                       |     1 |    36 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | HT03_IDX                   |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=999)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT03); attributes=(ordered); name="select * from ht03 where object_id=999"

Statistics
----------------------------------------------------------
        178  recursive calls
          0  db block gets
         27  consistent gets
          0  physical reads
          0  redo SIZE
        566  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          6  sorts (memory)
          0  sorts (disk)
          1  ROWS processed


同时在11gR2中,oracle在dba_tables和all_tables中增加一个字段,RESULT_CACHE。

SQL> SELECT owner,TABLE_NAME,RESULT_CACHE FROM dba_tables WHERE owner='ROGER';

OWNER                          TABLE_NAME                     RESULT_
------------------------------ ------------------------------ -------
ROGER                          HT04                           FORCE
ROGER                          HT03                           FORCE
ROGER                          HT02                           DEFAULT
ROGER                          HT01                           DEFAULT

Elapsed: 00:00:02.75
关于字段RESULT_CACHE其中有3个属性,分别为DEFAULT,FORCE和MANUAL,大家可以参考11.2的官方文档。
这里有点需要说明的是,必然当表结构或定义发变化了,那么query cache 缓存的信息都将被清除,如下例子。

SQL> SET autot traceonly
SQL> SELECT /*+ RESULT_CACHE */ * FROM ht01 WHERE object_id=100;

Elapsed: 00:00:00.03

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | b500gqatyy0zq32az39dhnk3fb |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=100)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=100"

Statistics
----------------------------------------------------------
         44  recursive calls
          0  db block gets
         10  consistent gets
          2  physical reads
          0  redo SIZE
        560  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> DESC ht01

Name                  NULL     TYPE
--------------------- -------- ----------------------
OWNER                          VARCHAR2(30)
OBJECT_NAME                    VARCHAR2(128)
OBJECT_ID                      NUMBER

SQL> ALTER TABLE ht01 MODIFY (owner VARCHAR2(40));

TABLE altered.
Elapsed: 00:00:00.22

SQL>  SELECT /*+ RESULT_CACHE */ * FROM ht01 WHERE object_id=100;

Elapsed: 00:00:00.02

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | b500gqatyy0zq32az39dhnk3fb |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=100)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=100"

Statistics
----------------------------------------------------------
        178  recursive calls
          0  db block gets
         27  consistent gets
          0  physical reads
          0  redo SIZE
        560  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          6  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> SELECT /*+ RESULT_CACHE */ * FROM ht01 WHERE object_id=100;

Elapsed: 00:00:00.02

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | b500gqatyy0zq32az39dhnk3fb |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=100)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=100"

Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo SIZE
        560  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> SELECT /*+ RESULT_CACHE */ * FROM ht01 WHERE object_id=100;

Elapsed: 00:00:00.01

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | b500gqatyy0zq32az39dhnk3fb |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=100)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=100"

Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo SIZE
        560  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed
从上面的信息来看,我想已经完全可以说明问题了,如何有人说这还不能说明问题的话,那请看下面:

SQL> conn /AS sysdba
Connected.

SQL> ALTER SESSION SET events 'immediate trace name heapdump level 2';

SESSION altered.
Elapsed: 00:00:04.38

SQL> @ gettrc.SQL

TRACE_FILE_NAME
------------------------------------------------------------------------------------
/oracle/product/diag/rdbms/roger/roger/trace/roger_ora_4106.trc

Elapsed: 00:00:00.82

SQL> !
[oracle@roger ~]$ grep -i Result  /oracle/product/diag/rdbms/roger/roger/trace/roger_ora_4106.trc

  Chunk 24bdecac sz=    32816    freeable  "Result Cache   "  ds=0x272758b4
  Chunk 24be6cdc sz=    32816    freeable  "Result Cache   "  ds=0x272758b4
  Chunk 24beed0c sz=    32816    recreate  "Result Cache   "  latch=(nil)

[oracle@roger ~]$
SQL> oradebug setmypid
Statement processed.

SQL> oradebug dump heapdump_addr 2 656890036;
Statement processed.

SQL> oradebug tracefile_name
/oracle/product/diag/rdbms/roger/roger/trace/roger_ora_6683.trc
[root@roger ~]# grep -i ht01 /oracle/product/diag/rdbms/roger/roger/trace/roger_ora_6683.trc

24BE11A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE15A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE11A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE15A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
下面我们修改表ht01的表结构,然后再次dump 看看结果如何。

SQL> SET autot off
SQL> ALTER TABLE ht01 MODIFY (owner VARCHAR2(50));

TABLE altered.
Elapsed: 00:00:00.06

SQL> SET autot traceonly
SQL>  SELECT /*+ RESULT_CACHE */ * FROM ht01 WHERE object_id=101;

Elapsed: 00:00:00.05

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | br1m2nyfp7v9c5drfp1gn5xp92 |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=101)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=101"

Statistics
----------------------------------------------------------
        178  recursive calls
          0  db block gets
         27  consistent gets
          0  physical reads
          0  redo SIZE
        563  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          6  sorts (memory)
          0  sorts (disk)
          1  ROWS processed

SQL> /

Elapsed: 00:00:00.01

Execution Plan
----------------------------------------------------------
Plan hash VALUE: 2671155529

-----------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name                       | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                            |     1 |    24 |     2   (0)| 00:00:01 |
|   1 |  RESULT CACHE                | br1m2nyfp7v9c5drfp1gn5xp92 |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID| HT01                       |     1 |    24 |     2   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | IDX_HT01_ID                |     1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------

Predicate Information (IDENTIFIED BY operation id):
---------------------------------------------------

   3 - access("OBJECT_ID"=101)

RESULT Cache Information (IDENTIFIED BY operation id):
------------------------------------------------------

   1 - column-COUNT=3; dependencies=(ROGER.HT01); attributes=(ordered); name="select /*+ RESULT_CACHE */ * from ht01 where object_id=101"

Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo SIZE
        563  bytes sent via SQL*Net TO client
        415  bytes received via SQL*Net FROM client
          2  SQL*Net roundtrips TO/FROM client
          0  sorts (memory)
          0  sorts (disk)
          1  ROWS processed


SQL>  oradebug setmypid
Statement processed.

SQL> oradebug dump heapdump_addr 2 656890036;http://www.oracleplus.net
Statement processed.

SQL> oradebug tracefile_name
/oracle/product/diag/rdbms/roger/roger/trace/roger_ora_28227.trc
[root@roger ~]# grep -i ht01 /oracle/product/diag/rdbms/roger/roger/trace/roger_ora_28227.trc

24BE11A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE15A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE19A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]  
24BE11A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE15A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]
24BE19A0 6F726620 7468206D 77203130 65726568  [ from ht01 where]

从上面可以看出多了2条信息,24BE19A0。

从上面的实验来看,我们可以推断出oracle这里应该是这样管理的,那就是即使表结构定义发生改变了,那么原来cache的信息仍然存在query cache中,当然,当cache不够用了,也是会被清除掉的,至于说oracle这里是如何去判断如何不去选择旧的cache信息,那么我就不得而知了。

--------------------------------------ORACLE-DBA----------------------------------------

最权威、专业的Oracle案例资源汇总之【学习笔记】Oracle 11G新特性query result cache(3)深入研究笔记

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关键词:

Oracle 11G新特性详细介绍

Oracle query result cache深入研究笔记