Oracle 物化视图 详细错误描述 查看方法

 

Oracle的物化视图提供了强大的功能，可以用于预先计算并保存表连接或聚集等耗时较多的操作的结果，这样，在执行查询时，就可以避免进行这些耗时的操作，而从快速的得到结果。关于物化视图相关的说明参考：

 

Oracle 物化视图

http://blog.csdn.net/tianlesoftware/article/details/4713553

 

Oracle 物化视图 快速刷新 限制 说明

http://blog.csdn.net/tianlesoftware/article/details/7719679

 

            在我们创建物化视图失败时，Oracle给的错误信息过于简单，不能帮助我们定位具体的问题，Oracle 为此提供了dbms_mview.explain_mview过程帮助我们快速定位问题的原因。

 

一.EXPLAIN_MVIEW 说明

使用explain_mview过程先要建立mv_capabilities_table表，建表的脚步是$oracle_home/rdbms/admin/utlxmv.sql。（explain_mview过程是两个过程的重载，一个输出到mv_capabilities_table表，另一个以pl/sql的varray格式输出）。

 

SQL>@?/rdbms/admin/utlxmv.sql

Table created.

 

            查看utlxmv.sql 脚本，可以看到mv_capabilities_tables 表的定义：

 

CREATETABLEMV_CAPABILITIES_TABLE

  (STATEMENT_ID         VARCHAR(30), --Client-supplied unique statement identifier

   MVOWNER              VARCHAR(30), -- NULLfor SELECT based EXPLAIN_MVIEW

   MVNAME               VARCHAR(30), -- NULLfor SELECT based EXPLAIN_MVIEW

   CAPABILITY_NAME      VARCHAR(30),  -- A descriptivename of the particular

                                     --capability:

                                     --REWRITE

                                     --   Can do at least full text match

                                     --   rewrite

                                     --REWRITE_PARTIAL_TEXT_MATCH

                                      --   Can do at leat full and partial

                                     --   text match rewrite

                                     --REWRITE_GENERAL

                                     --   Can do all forms of rewrite

                                      -- REFRESH

                                     --   Can do at least complete refresh

                                     --REFRESH_FROM_LOG_AFTER_INSERT

                                     --   Can do fast refresh from an mv log

                                     --   or change capture table at least

                                     --   when update operations are

                                     --   restricted to INSERT

                                     --REFRESH_FROM_LOG_AFTER_ANY

                                     --   can do fast refresh from an mv log

                                     --   or change capture table after any

                                      --  combination of updates

                                     -- PCT

                                     --   Can do Enhanced Update Tracking on

                                     --   the table named in the RELATED_NAME

                                      --  column.  EUT is needed for fast

                                     --   refresh after partitioned

                                     --   maintenance operations on the table

                                     --   named in the RELATED_NAME column

                                     --   and to do non-stale tolerated

                                     --   rewrite when the mv is partially

                                     --   stale with respect to the table

                                     --   named in the RELATED_NAME column.

                                     --   EUT can also sometimes enable fast

                                     --   refresh of updates to the table

                                      --  named in the RELATED_NAME column

                                     --   when fast refresh from an mv log

                                     --   or change capture table is not

                                     --   possilbe.

  POSSIBLE             CHARACTER(1), -- T = capabilityis possible

                                     -- F =capability is not possible

   RELATED_TEXT         VARCHAR(2000),-- Owner.table.column, alias name,etc.

                                     -- related to this message.  The

                                     --specific meaning of this column

                                     --depends on the MSGNO column.  See

                                     -- thedocumentation for

                                     --DBMS_MVIEW.EXPLAIN_MVIEW() for details

   RELATED_NUM          NUMBER,       -- When there is a numeric value

                                     --associated with a row, it goes here.

                                      -- The specific meaning of thiscolumn

                                     --depends on the MSGNO column.  See

                                     -- thedocumentation for

                                     --DBMS_MVIEW.EXPLAIN_MVIEW() for details

   MSGNO                INTEGER,      -- When available, QSM message #

                                     --explaining why not possible or more

                                     --details when enabled.

   MSGTXT               VARCHAR(2000),-- Text associated with MSGNO.

   SEQ                  NUMBER);     

              -- Useful in ORDERBY clause when

                                     --selecting from this table.

 

 

二．Explain_mview 使用示例

 

dbms_mview.explain_mview能分析三种不同的物化视图代码，分别是：

            1.定义的查询

2.一个create materialized view的语句

3.一个存在的物化视图

 

因为物化视图在语法有一定的限制，所以在创建物化视图之前我们可以先使用explain_mview 过程来验证一下语法上的问题。如：

 

SQL> execdbms_mview.explain_mview('select * from dave');

PL/SQL proceduresuccessfully completed.

 

            --然后查看mv_capabilities_table 表：

 

SQL> desc mv_capabilities_table

 Name

 ---------------------------------

 STATEMENT_ID

 MVOWNER

 MVNAME

 CAPABILITY_NAME

 POSSIBLE

 RELATED_TEXT

 RELATED_NUM

 MSGNO

 MSGTXT

 SEQ

 

SQL> selectcapability_name,possible,msgtxt from mv_capabilities_table;

 

CAPABILITY_NAME                P MSGTXT

------------------------------ ------------------------------------------------------------------------------------

PCT                            N

REFRESH_COMPLETE               N no primary key constraint inthe master table

--这里提示我们主表没有主键，

REFRESH_FAST                   N

REWRITE                        N

PCT_TABLE                      N Oracle error: seeRELATED_NUM and RELATED_TEXT for details

REFRESH_FAST_AFTER_INSERT      N the detail table does not have amaterialized view log

REFRESH_FAST_AFTER_ONETAB_DML  N see the reason why REFRESH_FAST_AFTER_INSERTis disabled

REFRESH_FAST_AFTER_ANY_DML     N see the reason whyREFRESH_FAST_AFTER_ONETAB_DML is disabled

REFRESH_FAST_PCT               N PCT is not possible on any ofthe detail tables in the materialized view

REWRITE_FULL_TEXT_MATCH        NOracle error: see RELATED_NUM and RELATED_TEXT for details

REWRITE_PARTIAL_TEXT_MATCH     N materialized view cannot support anytype of query rewrite

REWRITE_GENERAL                N materialized view cannotsupport any type of query rewrite

REWRITE_PCT                    N general rewrite is notpossible or PCT is not possible on any of the detail tables

PCT_TABLE_REWRITE              N Oracle error: see RELATED_NUMand RELATED_TEXT for details

--这里会显示所有不符合的地方。

 

 

SQL> create materialized view mv_daverefresh fast on demand as select * from dave;

create materialized view mv_dave refreshfast on demand as select * from dave

                                                                        *

ERROR at line 1:

ORA-12014: 表 'DAVE' 不包含主键约束条件

--如果我们直接使用上面的语句，就会出现没有主键的错误。

 

 

我们创建一个新的物化视图，然后使用explain_mview 来验证：

SQL> create table anqing as select *from all_users;

Table created.

 

 

SQL> create materialized view mv_daverefresh force on demand as select * from anqing;

Materialized view created.

 

SQL> exec dbms_mview.explain_mview('mv_dave');

PL/SQL procedure successfully completed.

 

SQL> selectcapability_name,possible,msgtxt from mv_capabilities_table wheremvname='MV_DAVE';

 

CAPABILITY_NAME                P MSGTXT

------------------------------ -----------------------------------------------------------------------------------

PCT                            N

REFRESH_COMPLETE               Y

REFRESH_FAST                   N

REWRITE                        N

PCT_TABLE                      N Oracle error: seeRELATED_NUM and RELATED_TEXT for details

REFRESH_FAST_AFTER_INSERT      N does not meet the requirements of aprimary key mv

REFRESH_FAST_AFTER_ONETAB_DML  N see the reason whyREFRESH_FAST_AFTER_INSERT is disabled

REFRESH_FAST_AFTER_ANY_DML     N see the reason whyREFRESH_FAST_AFTER_ONETAB_DML is disabled

REFRESH_FAST_PCT               N PCT is not possible on any ofthe detail tables in the materialized view

REWRITE_FULL_TEXT_MATCH        N Oracle error: see RELATED_NUM andRELATED_TEXT for details

REWRITE_FULL_TEXT_MATCH        N query rewrite is disabled on thematerialized view

REWRITE_PARTIAL_TEXT_MATCH     N materialized view cannot support anytype of query rewrite

REWRITE_PARTIAL_TEXT_MATCH     N query rewrite is disabled on thematerialized view

REWRITE_GENERAL                N materialized view cannotsupport any type of query rewrite

REWRITE_GENERAL                N query rewrite is disabled onthe materialized view

REWRITE_PCT                    N general rewrite is not possible or PCT isnot possible on any of the detail tables

PCT_TABLE_REWRITE              N Oracle error: see RELATED_NUMand RELATED_TEXT for details

 

17 rows selected.

 

--这里就ok了。

 

 

 

 

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