研究v$sqlarea,v$sql,v$sqltext

以下内容转自http://lzfhope.blog.163.com/blog/static/63639922008101955913105

通过看这个表的结构，可以了解共享池中，SQL是如何运行的,这样可以了解不少关键的信息.

可以了解SQL全文,执行使用的内存，消耗的CPU，被装载的次数等等比较有意义的信息。

通过这个视图，可以了解最近被执行最多次数的SQL语句，被最多用户执行的SQL语句.当然共享池要足够大，设计的语句也应该尽量考虑到共享(例如一个很简单的就是多考虑变量绑定)，研究这个对于了解性能还是有一定作用的。
SQL_TEXT VARCHAR2(1000)

SQL前一千个字符 内容.

SQL_FULLTEXT CLOB

SQL全文

SQL_ID VARCHAR2(13)

SQL identifier of the parent cursor in the library cache

SHARABLE_MEM NUMBER

使用了多少共享内存(包含子游标所使用的)

PERSISTENT_MEM NUMBER

打开的游标其生命周期所消耗的固定内存(包含子有效的固定内存)

RUNTIME_MEM NUMBER

游标运行时候所需要的内容(包含子游标的)

SORTS NUMBER

所有的排序测试(包含子游标的)

VERSION_COUNT NUMBER

Number of child cursors that are present in the cache under this parent

LOADED_VERSIONS NUMBER

Number of child cursors that are present in the cache and have their context heap (KGL heap 6) loaded

OPEN_VERSIONS NUMBER

The number of child cursors that are currently open under this current parent

USERS_OPENING NUMBER

共有多少用户打开它(包含子游标)

FETCHES NUMBER Number

Numberof fetches associated with the SQL statement

EXECUTIONS NUMBER

总共执行次数(包含子游标)

PX_SERVERS_EXECUTIONS NUMBER

Total number of executions performed by Parallel eXecution Servers. The

value is 0 when the statement has never been executed in parallel.

END_OF_FETCH_COUNT NUMBER

完整执行的次数,通常小于总共执行次数.

Number of times this cursor was fully executed since the cursor was brought into the library cache. The value of this statistic is not incremented when the cursor is partially executed, either because it failed during the execution or because only the first few rows produced by this cursor are fetched before the cursor is closed or re-executed. By definition,the value of the END_OF_FETCH_COUNT column should be less or equal to the value of the EXECUTIONS column.

USERS_EXECUTING NUMBER

共多少个用户执行(..) (..)表示包含子游标,下同.

LOADS NUMBER

对象被装载或者重载的次数

FIRST_LOAD_TIME VARCHAR2(19)

第一次装载的时间.

INVALIDATIONS NUMBER

Total number of invalidations over all the child cursors

PARSE_CALLS NUMBER

Sum of all parse calls to all the child cursors under this parent 统共分析的次数(..)

DISK_READS NUMBER

Sum of the number of disk reads over all child cursors

DIRECT_WRITES NUMBER

Sum of the number of direct writes over all child cursors

BUFFER_GETS NUMBER

Sum of buffer gets over all child cursors

APPLICATION_WAIT_TIME NUMBER

Application wait time (in microseconds)

CONCURRENCY_WAIT_TIME NUMBER

Concurrency wait time (in microseconds)

CLUSTER_WAIT_TIME

NUMBER Cluster wait time (in microseconds)

USER_IO_WAIT_TIME

NUMBER User I/O Wait Time (in microseconds)

PLSQL_EXEC_TIME

NUMBER PL/SQL execution time (in microseconds)

JAVA_EXEC_TIME NUMBER

Java execution time (in microseconds)

ROWS_PROCESSED NUMBER

处理了多少条记录

COMMAND_TYPE NUMBER

Oracle command type definition

OPTIMIZER_MODE VARCHAR2(10)

Mode under which the SQL statement was executed

OPTIMIZER_COST NUMBER

Cost of this query given by the optimizer

OPTIMIZER_ENV RAW(703)

Optimizer environment

OPTIMIZER_ENV_HASH_VALUE NUMBER

Hash value for the optimizer environmen

PARSING_USER_ID NUMBER

User ID of the user that has parsed the very first cursor under this parent

PARSING_SCHEMA_ID NUMBER

Schema ID that was used to parse this child cursor

PARSING_SCHEMA_NAME VARCHAR2(30)

Schema name that was used to parse this child cursor

KEPT_VERSIONS NUMBER

Number of child cursors that have been marked to be kept using the DBMS_SHARED_POOL package

ADDRESS RAW(4 | 8)

Address of the handle to the parent for this cursor

HASH_VALUE NUMBER

Hash value of the parent statement in the library cache

OLD_HASH_VALUE NUMBER

Old SQL hash value

PLAN_HASH_VALUE NUMBER

Numerical representation of the SQL plan for this cursor. Comparing one PLAN_HASH_VALUE to another easily identifies whether or not two plans are the same (rather than comparing the two plans line by line)

MODULE VARCHAR2(64)

Contains the name of the module that was executing at the time that the SQL statement was first parsed as set by calling DBMS_APPLICATION_INFO.SET_MODULE

MODULE_HASH NUMBER

Hash value of the module that is named in the MODULE column

ACTION VARCHAR2(64)

Contains the name of the action that was executing at the time that the

SQL statement was first parsed as set by calling

DBMS_APPLICATION_INFO.SET_ACTION

ACTION_HASH NUMBER

Hash value of the action that is named in the ACTION column

SERIALIZABLE_ABORTS NUMBER

Number of times the transaction fails to serialize, producing ORA-08177 errors, totalled over all the child cursors

OUTLINE_CATEGORY VARCHAR2(64)

If an outline was applied during construction of the cursor, then this column displays the category of that outline. Otherwise the column is left

blank.



CPU_TIME NUMBER

分析,执行和提取所消耗的时间(单位为微秒)

CPU time (in microseconds) used by this cursor for parsing, executing, and fetching

ELAPSED_TIME NUMBER

客观上分析,执行和提取所消耗的时间(单位为微秒)

这个时间通常比CPU_TIME长,因为可能还包含其它时间

OUTLINE_SID VARCHAR2(40)

Outline session identifier

LAST_ACTIVE_CHILD_ADDRESS RAW(4)

Address (identifier) of the child cursor that was the last to be active in the group (that is, the child cursor on behalf of which statistics in V$SQL were updated)

REMOTE VARCHAR2(1)

Indicates whether the cursor is remote mapped (Y) or not (N)

OBJECT_STATUS VARCHAR2(19)

Status of the cursor:

■ VALID - Valid, authorized without errors

■ VALID_AUTH_ERROR - Valid, authorized with authorization errors

■ VALID_COMPILE_ERROR - Valid, authorized with compilation errors

■ VALID_UNAUTH - Valid, unauthorized

■ INVALID_UNAUTH - Invalid, unauthorized

■ INVALID - Invalid, unauthorized but keep the timestamp

LITERAL_HASH_VALUE NUMBER

Hash value of the literals which are replaced with system-generated bind variables and are to be matched, when CURSOR_SHARING is used. This is not the hash value for the SQL statement. If CURSOR_SHARING is no used, then the value is 0.

LAST_LOAD_TIME DATE

执行计划最后被此装载的时间.

Time at which the query plan (heap 6) was loaded into the library cache

IS_OBSOLETE VARCHAR2(1)

Indicates whether the cursor has become obsolete (Y) or not (N) happen if the number of child cursors is too large.

CHILD_LATCH NUMBER

Child latch number that is protecting the cursor

SQL_PROFILE VARCHAR2(64)

SQL profile

PROGRAM_ID NUMBER

Program identifier

PROGRAM_LINE# NUMBER

Program line number

EXACT_MATCHING_SIGNATURE NUMBER

The signature used when the CURSOR_SHARING parameter is set to EXACT

FORCE_MATCHING_SIGNATURE NUMBER

The signature used when the CURSOR_SHARING parameter is set to FORCE

LAST_ACTIVE_TIME DATE

最后换一次查询计划被激活的时间.

Time at which the query plan was last active

BIND_DATA RAW(2000)

Bind data

其中PROGRAM_ID,PROGRAM_LINE#可以用于定位是那个程序（通常指过程，函数或者是其它包裹等），可以用于跟踪。

SELECT T.USER_NAME ,e.SQL_FULLTEXT,E.PROGRAM_ID,E.PROGRAM_LINE#,X.OBJECT_NAME

FROM V$OPEN_CURSOR T, V$SESSION D, v$sqlarea e

JOIN ALL_OBJECTS X ON X.OBJECT_ID=E.PROGRAM_ID

WHERE T.SID = D.SID

and t.SQL_ID = e.SQL_ID

AND T.USER_NAME IN ('DM', 'WH', 'IPD', 'MK')
关于共同点：

1）都存储了sql内容

2) 记录的都是位于内存中的sql内容

3) 因为是内存，所以都不保留历史记录
不同点：

1)存储的为止不都是相同。其中v$sql和v$sqlarea存储的sql都是位于shared sql area中的sql,而v$sqltext是位于sga中的sql。但文档没有明确说明这里的sga是否还包含了psa(私有sql区域－－共享服务器模式下）。

2)存储sql的方式也不同，v$sql和v$sqlarea都是用一行来存储sql全文，而v$sqltext用一行存储sql的一行。

3)v$sql不存储包含group by 的sql语句。通常这个视图，在每个查询执行完成后更新，但对于执行很久的sql,它是每5秒更新一次，这点对于查看sql执行状态是有意义的。

4)存储的明细不同－－这是最基本的。

后顺便提一下，v$sqltext_with_newline和v$sqltext是一样，不同的是前者并把换行符和tab替换为空格 ，这样更容易阅读。V$SQLSTATS和V$SQL,v$sqlarea一样都有提供CPU的统计数据.
有关内存结构请参见 http://lzfhope.blog.163.com/blog/static/6363992200863012124663/