v$sql,v$sqlarea,v$sqltext 和 v$sql_plan 说明

一. 先看官网对这几个视图的说明（ORACLE 11gR2）

1.1 V$SQL

V$SQL lists statistics on shared SQL areas without the GROUP BY clause and contains one row for each child of the original SQL text entered. Statistics displayed in V$SQL are normally updated at the end of query execution. However, for long running queries, they are updated every 5 seconds. This makes it easy to see the impact of long running SQL statements while they are still in progress.

Column	Datatype	Description
SQL_TEXT	VARCHAR2(1000)	First thousand characters of the SQL text for the current cursor
SQL_FULLTEXT	CLOB	Full text for the SQL statement exposed as a CLOB column. The full text of a SQL statement can be retrieved using this column instead of joining with the V$SQLTEXT dynamic performance view.
SQL_ID	VARCHAR2(13)	SQL identifier of the parent cursor in the library cache
SHARABLE_MEM	NUMBER	Amount of shared memory used by the child cursor (in bytes)
PERSISTENT_MEM	NUMBER	Fixed amount of memory used for the lifetime of the child cursor (in bytes)
RUNTIME_MEM	NUMBER	Fixed amount of memory required during the execution of the child cursor
SORTS	NUMBER	Number of sorts that were done for the child cursor
LOADED_VERSIONS	NUMBER	Indicates whether the context heap is loaded (1) or not (0)
OPEN_VERSIONS	NUMBER	Indicates whether the child cursor is locked (1) or not (0)
USERS_OPENING	NUMBER	Number of users executing the statement
FETCHES	NUMBER	Number of fetches associated with the SQL statement
EXECUTIONS	NUMBER	Number of executions that took place on this object since it was brought into the library cache
PX_SERVERS_EXECUTIONS	NUMBER	Total number of executions performed by parallel execution servers (0 when the statement has never been executed in parallel)
END_OF_FETCH_COUNT	NUMBER	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	Number of users executing the statement
LOADS	NUMBER	Number of times the object was either loaded or reloaded
FIRST_LOAD_TIME	VARCHAR2(19)	Timestamp of the parent creation time
INVALIDATIONS	NUMBER	Number of times this child cursor has been invalidated
PARSE_CALLS	NUMBER	Number of parse calls for this child cursor
DISK_READS	NUMBER	Number of disk reads for this child cursor
DIRECT_WRITES	NUMBER	Number of direct writes for this child cursor
BUFFER_GETS	NUMBER	Number of buffer gets for this child cursor
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	Total number of rows the parsed SQL statement returns
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(2000)	Optimizer environment
OPTIMIZER_ENV_HASH_VALUE	NUMBER	Hash value for the optimizer environment
PARSING_USER_ID	NUMBER	User ID of the user who originally built this child cursor
PARSING_SCHEMA_ID	NUMBER	Schema ID that was used to originally build this child cursor
PARSING_SCHEMA_NAME	VARCHAR2(30)	Schema name that was used to originally build this child cursor
KEPT_VERSIONS	NUMBER	Indicates whether this child cursor has been marked to be kept pinned in the cache using the DBMS_SHARED_POOL package
ADDRESS	RAW(4 | 8)	Address of the handle to the parent for this cursor
TYPE_CHK_HEAP	RAW(4)	Descriptor of the type check heap for this child 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	Numeric 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).
CHILD_NUMBER	NUMBER	Number of this child cursor
SERVICE	VARCHAR2(64)	Service name
SERVICE_HASH	NUMBER	Hash value for the name listed in the SERVICEcolumn
MODULE	VARCHAR2(64)	Contains the name of the module that was executing at the time that the SQL statement was first parsed, which is set by calling DBMS_APPLICATION_INFO.SET_MODULE
MODULE_HASH	NUMBER	Hash value of the module listed 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, which is set by calling DBMS_APPLICATION_INFO.SET_ACTION
ACTION_HASH	NUMBER	Hash value of the action listed in the ACTION column
SERIALIZABLE_ABORTS	NUMBER	Number of times the transaction failed to serialize, producing ORA-08177 errors, per cursor
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	CPU time (in microseconds) used by this cursor for parsing, executing, and fetching
ELAPSED_TIME	NUMBER	Elapsed time (in microseconds) used by this cursor for parsing, executing, and fetching
OUTLINE_SID	NUMBER	Outline session identifier
CHILD_ADDRESS	RAW(4 | 8)	Address of the child cursor
SQLTYPE	NUMBER	Denotes the version of the SQL language used for this statement
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 not used, then the value is 0.
LAST_LOAD_TIME	VARCHAR2(19)	Time at which the query plan was loaded into the library cache
IS_OBSOLETE	VARCHAR2(1)	Indicates whether the cursor has become obsolete (Y) or not (N). This can happen if the number of child cursors is too large.
IS_BIND_SENSITIVE	VARCHAR2(1)	Indicates whether the cursor is bind sensitive (Y) or not (N). A query is considered bind-sensitive if the optimizer peeked at one of its bind variable values when computing predicate selectivities and where a change in a bind variable value may cause the optimizer to generate a different plan.
IS_BIND_AWARE	VARCHAR2(1)	Indicates whether the cursor is bind aware (Y) or not (N). A query is considered bind-aware if it has been marked to use extended cursor sharing. The query would already have been marked as bind-sensitive.
IS_SHAREABLE	VARCHAR2(1)	Indicates whether the cursor can be shared (Y) or not (N)
CHILD_LATCH	NUMBER	Child latch number that is protecting the cursor. This column is obsolete and maintained for backward compatibility.
SQL_PROFILE	VARCHAR2(64)	SQL profile used for this statement, if any
SQL_PATCH	VARCHAR2(30)	SQL patch used for this statement, if any
SQL_PLAN_BASELINE	VARCHAR2(30)	SQL plan baseline used for this statement, if any
PROGRAM_ID	NUMBER	Program identifier
PROGRAM_LINE#	NUMBER	Program line number
EXACT_MATCHING_SIGNATURE	NUMBER	Signature calculated on the normalized SQL text. The normalization includes the removal of white space and the uppercasing of all non-literal strings.
FORCE_MATCHING_SIGNATURE	NUMBER	Signature used when the CURSOR_SHARING parameter is set to FORCE
LAST_ACTIVE_TIME	DATE	TIme at which the query plan was last active
BIND_DATA	RAW(2000)	Bind data
TYPECHECK_MEM	NUMBER	Typecheck memory
IO_CELL_OFFLOAD_ELIGIBLE_BYTES	NUMBER	Number of I/O bytes which can be filtered by the Exadata storage system See Also: Oracle Exadata Storage Server Software documentation for more information
IO_INTERCONNECT_BYTES	NUMBER	Number of I/O bytes exchanged between Oracle Database and the storage system
PHYSICAL_READ_REQUESTS	NUMBER	Number of physical read I/O requests issued by the monitored SQL
PHYSICAL_READ_BYTES	NUMBER	Number of bytes read from disks by the monitored SQL
PHYSICAL_WRITE_REQUESTS	NUMBER	Number of physical write I/O requests issued by the monitored SQL
PHYSICAL_WRITE_BYTES	NUMBER	Number of bytes written to disks by the monitored SQL
OPTIMIZED_PHY_READ_REQUESTS	NUMBER	Number of physical read I/O requests from Database Smart Flash Cache issued by the monitored SQL
LOCKED_TOTAL	NUMBER	Total number of times the child cursor has been locked
PINNED_TOTAL	NUMBER	Total number of times the child cursor has been pinned
IO_CELL_UNCOMPRESSED_BYTES	NUMBER	Number of uncompressed bytes (that is, size after decompression) that are offloaded to the Exadata cells See Also: Oracle Exadata Storage Server Software documentation for more information
IO_CELL_OFFLOAD_RETURNED_BYTES	NUMBER	Number of bytes that are returned by the Exadata cell for smart scan only (that is, not including bytes for other database I/O) See Also: Oracle Exadata Storage Server Software documentation for more information

1.2 V$SQLAREA

V$SQLAREA displays statistics on shared SQL areas and contains one row per SQL string. It provides statistics on SQL statements that are in memory, parsed, and ready for execution.

Column	Datatype	Description
SQL_TEXT	VARCHAR2(1000)	First thousand characters of the SQL text for the current cursor
SQL_FULLTEXT	CLOB	All characters of the SQL text for the current cursor
SQL_ID	VARCHAR2(13)	SQL identifier of the parent cursor in the library cache
SHARABLE_MEM	NUMBER	Amount of shared memory used by a cursor. If multiple child cursors exist, then the sum of all shared memory used by all child cursors.
PERSISTENT_MEM	NUMBER	Fixed amount of memory used for the lifetime of an open cursor. If multiple child cursors exist, then the fixed sum of memory used for the lifetime of all the child cursors.
RUNTIME_MEM	NUMBER	Fixed amount of memory required during execution of a cursor. If multiple child cursors exist, then the fixed sum of all memory required during execution of all the child cursors.
SORTS	NUMBER	Sum of the number of sorts that were done for all the child cursors
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 loaded
OPEN_VERSIONS	NUMBER	Number of child cursors that are currently open under this current parent
USERS_OPENING	NUMBER	Number of users that have any of the child cursors open
FETCHES	NUMBER	Number of fetches associated with the SQL statement
EXECUTIONS	NUMBER	Total number of executions, totalled over all the child cursors
PX_SERVERS_EXECUTIONS	NUMBER	Total number of executions performed by parallel execution servers (0 when the statement has never been executed in parallel)
END_OF_FETCH_COUNT	NUMBER	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	Total number of users executing the statement over all child cursors
LOADS	NUMBER	Number of times the object was loaded or reloaded
FIRST_LOAD_TIME	VARCHAR2(19)	Timestamp of the parent creation time
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
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	Total number of rows processed on behalf of this SQL statement
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(2000)	Optimizer environment
OPTIMIZER_ENV_HASH_VALUE	NUMBER	Hash value for the optimizer environment
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	Numeric 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 failed 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	CPU time (in microseconds) used by this cursor for parsing, executing, and fetching
ELAPSED_TIME	NUMBER	Elapsed time (in microseconds) used by this cursor for parsing, executing, and fetching
OUTLINE_SID	VARCHAR2(40)	Outline session identifier
LAST_ACTIVE_CHILD_ADDRESS	RAW(4 | 8)	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 not used, then the value is 0.
LAST_LOAD_TIME	DATE	Time at which the query plan was loaded into the library cache
IS_OBSOLETE	VARCHAR2(1)	Indicates whether the cursor has become obsolete (Y) or not (N). This can happen if the number of child cursors is too large.
IS_BIND_SENSITIVE	VARCHAR2(1)	Indicates whether the cursor is bind sensitive (Y) or not (N). A query is considered bind-sensitive if the optimizer peeked at one of its bind variable values when computing predicate selectivities and where a change in a bind variable value may cause the optimizer to generate a different plan.
IS_BIND_AWARE	VARCHAR2(1)	Indicates whether the cursor is bind aware (Y) or not (N). A query is considered bind-aware if it has been marked to use extended cursor sharing. The query would already have been marked as bind-sensitive.
CHILD_LATCH	NUMBER	Child latch number that is protecting the cursor. This column is obsolete and maintained for backward compatibility.
SQL_PROFILE	VARCHAR2(64)	SQL profile used for this statement, if any
SQL_PATCH	VARCHAR2(30)	SQL patch used for this statement, if any
SQL_PLAN_BASELINE	VARCHAR2(30)	SQL plan baseline used for this statement, if any
PROGRAM_ID	NUMBER	Program identifier
PROGRAM_LINE#	NUMBER	Program line number
EXACT_MATCHING_SIGNATURE	NUMBER	Signature used when the CURSOR_SHARING parameter is set to EXACT
FORCE_MATCHING_SIGNATURE	NUMBER	Signature used when the CURSOR_SHARING parameter is set to FORCE
LAST_ACTIVE_TIME	DATE	Time at which the query plan was last active
BIND_DATA	RAW(2000)	Bind data
TYPECHECK_MEM	NUMBER	Typecheck memory
IO_CELL_OFFLOAD_ELIGIBLE_BYTES	NUMBER	Number of I/O bytes which can be filtered by the Exadata storage system See Also: Oracle Exadata Storage Server Software documentation for more information
IO_INTERCONNECT_BYTES	NUMBER	Number of I/O bytes exchanged between Oracle Database and the storage system
PHYSICAL_READ_REQUESTS	NUMBER	Number of physical read I/O requests issued by the monitored SQL
PHYSICAL_READ_BYTES	NUMBER	Number of bytes read from disks by the monitored SQL
PHYSICAL_WRITE_REQUESTS	NUMBER	Number of physical write I/O requests issued by the monitored SQL
PHYSICAL_WRITE_BYTES	NUMBER	Number of bytes written to disks by the monitored SQL
OPTIMIZED_PHY_READ_REQUESTS	NUMBER	Number of physical read I/O requests from Database Smart Flash Cache issued by the monitored SQL
LOCKED_TOTAL	NUMBER	Total number of times the child cursor has been locked
PINNED_TOTAL	NUMBER	Total number of times the child cursor has been pinned
IO_CELL_UNCOMPRESSED_BYTES	NUMBER	Number of uncompressed bytes (that is, size after decompression) that are offloaded to the Exadata cells See Also: Oracle Exadata Storage Server Software documentation for more information
IO_CELL_OFFLOAD_RETURNED_BYTES	NUMBER	Number of bytes that are returned by the Exadata cell for smart scan only (that is, not including bytes for other database I/O) See Also: Oracle Exadata Storage Server Software documentation for more information

1.3 V$SQLTEXT

V$SQLTEXT displays the text of SQL statements belonging to shared SQL cursors in the SGA.

Column	Datatype	Description
ADDRESS	RAW(4 | 8)	Used with HASH_VALUE to uniquely identify a cached cursor
HASH_VALUE	NUMBER	Used with ADDRESS to uniquely identify a cached cursor
SQL_ID	VARCHAR2(13)	SQL identifier of a cached cursor
COMMAND_TYPE	NUMBER	Code for the type of SQL statement (SELECT, INSERT, and so on)
PIECE	NUMBER	Number used to order the pieces of SQL text
SQL_TEXT	VARCHAR2(64)	A column containing one piece of the SQL text

1.4 V$SQL_PLAN

V$SQL_PLAN contains the execution plan information for each child cursor loaded in the library cache.

Column	Datatype	Description
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. The two columns ADDRESS and HASH_VALUE can be used to join with V$SQLAREA to add the cursor-specific information.
SQL_ID	VARCHAR2(13)	SQL identifier of the parent cursor in the library cache
PLAN_HASH_VALUE	NUMBER	Numerical representation of the SQL plan for the cursor. Comparing one PLAN_HASH_VALUE to another easily identifies whether or not two plans are the same (rather than comparing the two plans line by line).
CHILD_ADDRESS	RAW(4 | 8)	Address of the child cursor
CHILD_NUMBER	NUMBER	Number of the child cursor that uses this execution plan. The columns ADDRESS, HASH_VALUE, and CHILD_NUMBER can be used to join with V$SQL to add the child cursor-specific information.
TIMESTAMP	DATE	Date and time when the execution plan was generated
OPERATION	VARCHAR2(30)	Name of the internal operation performed in this step (for example, TABLE ACCESS)
OPTIONS	VARCHAR2(30)	A variation on the operation described in the OPERATION column (for example, FULL)
OBJECT_NODE	VARCHAR2(40)	Name of the database link used to reference the object (a table name or view name). For local queries that use parallel execution, this column describes the order in which output from operations is consumed.
OBJECT#	NUMBER	Object number of the table or the index
OBJECT_OWNER	VARCHAR2(30)	Name of the user who owns the schema containing the table or index
OBJECT_NAME	VARCHAR2(30)	Name of the table or index
OBJECT_ALIAS	VARCHAR2(65)	Alias for the object
OBJECT_TYPE	VARCHAR2(20)	Type of the object
OPTIMIZER	VARCHAR2(20)	Current mode of the optimizer for the first row in the plan (statement line), for example, CHOOSE. When the operation is a database access (for example, TABLE ACCESS), this column indicates whether or not the object is analyzed.
ID	NUMBER	A number assigned to each step in the execution plan
PARENT_ID	NUMBER	ID of the next execution step that operates on the output of the current step
DEPTH	NUMBER	Depth (or level) of the operation in the tree. It is not necessary to issue a CONNECT BY statement to get the level information, which is generally used to indent the rows from the PLAN_TABLE table. The root operation (statement) is level 0.
POSITION	NUMBER	Order of processing for all operations that have the same PARENT_ID
SEARCH_COLUMNS	NUMBER	Number of index columns with start and stop keys (that is, the number of columns with matching predicates)
COST	NUMBER	Cost of the operation as estimated by the optimizer's cost-based approach. For statements that use the rule-based approach, this column is null.
CARDINALITY	NUMBER	Estimate, by the cost-based optimizer, of the number of rows produced by the operation
BYTES	NUMBER	Estimate, by the cost-based optimizer, of the number of bytes produced by the operation
OTHER_TAG	VARCHAR2(35)	Describes the contents of the OTHER column. See EXPLAIN PLAN for values.
PARTITION_START	VARCHAR2(64)	Start partition of a range of accessed partitions
PARTITION_STOP	VARCHAR2(64)	Stop partition of a range of accessed partitions
PARTITION_ID	NUMBER	Step that computes the pair of values of the PARTITION_START and PARTITION_STOP columns
OTHER	VARCHAR2(4000)	Other information specific to the execution step that users may find useful. See EXPLAIN PLAN for values.
DISTRIBUTION	VARCHAR2(20)	Stores the method used to distribute rows from producer query servers to consumer query servers
CPU_COST	NUMBER	CPU cost of the operation as estimated by the optimizer's cost-based approach. For statements that use the rule-based approach, this column is null.
IO_COST	NUMBER	I/O cost of the operation as estimated by the optimizer's cost-based approach. For statements that use the rule-based approach, this column is null.
TEMP_SPACE	NUMBER	Temporary space usage of the operation (sort or hash-join) as estimated by the optimizer's cost-based approach. For statements that use the rule-based approach, this column is null.
ACCESS_PREDICATES	VARCHAR2(4000)	Predicates used to locate rows in an access structure. For example, start or stop predicates for an index range scan.
FILTER_PREDICATES	VARCHAR2(4000)	Predicates used to filter rows before producing them
PROJECTION	VARCHAR2(4000)	Expressions produced by the operation
TIME	NUMBER	Elapsed time (in seconds) of the operation as estimated by the optimizer's cost-based approach. For statements that use the rule-based approach, this column is null.
QBLOCK_NAME	VARCHAR2(30)	Name of the query block
REMARKS	VARCHAR2(4000)	Remarks
OTHER_XML	CLOB	Provides extra information specific to an execution step of the execution plan. The content of this column is structured using XML since multiple pieces of information can be stored there. This includes: · Name of the schema against which the query was parsed · Release number of the Oracle Database that produced the explain plan · Hash value associated with the execution plan · Name (if any) of the outline or the SQL profile used to build the execution plan · Indication of whether or not dynamic sampling was used to produce the plan · The outline data, a set of optimizer hints that can be used to regenerate the same plan

二. 查看GV$ 视图的定义语句

/* Formatted on 2011/1/10 15:54:44 (QP5 v5.115.810.9015) */

SELECT view_definition

FROM v$fixed_view_definition

WHERE view_name = 'GV$SQL';

可以使用上面的语句查询视图的定义语句。 这里查询的是GV$, 因为V$视图也是根据GV$出来的。 这个可以用上面的语句查询下V$SQL 就可以验证了。

GV$SQL的定义如下：

/* Formatted on 2011/1/10 16:08:04 (QP5 v5.115.810.9015) */

SELECT inst_id,kglnaobj,kglfnobj,kglobt03,kglobhs0

+ kglobhs1

+ kglobhs2

+ kglobhs3

+ kglobhs4

+ kglobhs5

+ kglobhs6

+ kglobt16,

kglobt08 + kglobt11,

kglobt10,

kglobt01,

DECODE (kglobhs6, 0, 0, 1),

DECODE (kglhdlmd, 0, 0, 1),

kglhdlkc,kglobt04,kglobt05,kglobt48, kglobt35,kglobpc6,kglhdldc,

SUBSTR (TO_CHAR (kglnatim, 'YYYY-MM-DD/HH24:MI:SS'), 1, 19),

kglhdivc, kglobt12, kglobt13, kglobwdw,

kglobt14, kglobwap, kglobwcc, kglobwcl,

kglobwui, kglobt42, kglobt43, kglobt15,

kglobt02,

DECODE (kglobt32, 0, 'NONE', 1, 'ALL_ROWS', 2, 'FIRST_ROWS',

3, 'RULE', 4, 'CHOOSE', 'UNKNOWN'),

kglobtn0, kglobcce, kglobcceh, kglobt17,

kglobt18, kglobts4, kglhdkmk, kglhdpar,

kglobtp0, kglnahsh, kglobt46, kglobt30,

kglobt09, kglobts5, kglobt48, kglobts0,

kglobt19, kglobts1, kglobt20, kglobt21,

kglobts2, kglobt06, kglobt07,

DECODE (kglobt28, 0, TO_NUMBER (NULL), kglobt28),

kglhdadr, kglobt29, DECODE (BITAND (kglobt00, 64), 64, 'Y', 'N'),

DECODE (kglobsta, 1, 'VALID', 2, 'VALID_AUTH_ERROR',

3, 'VALID_COMPILE_ERROR', 4, 'VALID_UNAUTH',

5, 'INVALID_UNAUTH', 6, 'INVALID'),

kglobt31,

SUBSTR (TO_CHAR (kglobtt0, 'YYYY-MM-DD/HH24:MI:SS'), 1, 19),

DECODE (kglobt33, 1, 'Y', 'N'),

DECODE (BITAND (kglobacs, 1), 1, 'Y', 'N'),

DECODE (BITAND (kglobacs, 2), 2, 'Y', 'N'),

DECODE (BITAND (kglobacs, 4), 4, 'Y', 'N'),

kglhdclt, kglobts3, kglobts7, kglobts6,

kglobt44, kglobt45, kglobt47, kglobt49,

kglobcla, kglobcbca, kglobt22, kglobt52,

kglobt53, kglobt54,kglobt55, kglobt56,

kglobt57, kglobt58, kglobt23, kglobt24,

kglobt59, kglobt53 - ( (kglobt55 + kglobt57) - kglobt52)

FROM x$kglcursor_child

GV$SQLTEXT 定义如下：

SELECT inst_id,

kglhdadr,

kglnahsh,

kglnasqlid,

kgloboct,

piece,

name

FROM x$kglna

WHERE kgloboct != 0

GV$SQLAREA 定义

/* Formatted on 2011/1/10 16:05:52 (QP5 v5.115.810.9015) */

SELECT inst_id, kglnaobj, kglfnobj, kglobt03,

kglobhs0 + kglobhs1 + kglobhs2 + kglobhs3

+ kglobhs4 + kglobhs5 + kglobhs6,

kglobt08 + kglobt11, kglobt10, kglobt01,

kglobccc, kglobclc, kglhdlmd, kglhdlkc,

kglobt04, kglobt05, kglobt48, kglobt35,

kglobpc6, kglhdldc,

SUBSTR (TO_CHAR (kglnatim, 'YYYY-MM-DD/HH24:MI:SS'), 1, 19),

kglhdivc, kglobt12, kglobt13, kglobwdw,

kglobt14, kglobwap, kglobwcc, kglobwcl,

kglobwui, kglobt42, kglobt43, kglobt15,

kglobt02,

DECODE (kglobt32, 0, 'NONE', 1, 'ALL_ROWS', 2, 'FIRST_ROWS',

3, 'RULE', 4, 'CHOOSE', 'UNKNOWN'),

kglobtn0, kglobcce, kglobcceh, kglobt17,

kglobt18, kglobts4, kglhdkmk, kglhdpar,

kglna hsh, kglobt46, kglobt30, kglobts0,

kglobt19, kglobts1, kglobt20, kglobt21,

kglobts2, kglobt06, kglobt07,

DECODE (kglobt28, 0, NULL, kglobt28),kglhdadr,

DECODE (BITAND (kglobt00, 64), 64, 'Y', 'N'),

DECODE (kglobsta, 1, 'VALID', 2, 'VALID_AUTH_ERROR', 3,

'VALID_COMPILE_ERROR',4, 'VALID_UNAUTH',5,

'INVALID_UNAUTH',6, 'INVALID'), kglobt31,kglobtt0,

DECODE (kglobt33, 1, 'Y', 'N'),

DECODE (BITAND (kglobacs, 1), 1, 'Y', 'N'),

DECODE (BITAND (kglobacs, 2), 2, 'Y', 'N'),

kglhdclt,kglobts3,kglobts7,kglobts6,

kglobt44,kglobt45,kglobt47,kglobt49,

kglobcla,kglobcbca,kglobt22,kglobt52,

kglobt53,kglobt54,kglobt55,kglobt56,

kglobt57, kglobt58, kglobt23,kglobt24,

kglobt59, kglobt53 - ( (kglobt55 + kglobt57) - kglobt52)

FROM x$kglcursor_child_sqlid

WHERE kglobt02 != 0

从上面的语句可以看出，这些视图都是根据x$视图来定义的。 对于X$视图，在我以前的Blog里有说明：

Oracle 动态性能视图

http://blog.csdn.net/tianlesoftware/archive/2010/09/04/5863191.aspx

在这篇blog的1.2节中对X$介绍：1.2 V$, V_$, GV$, X$ 视图说明

X$表包含了特定实例的各方面的信息，是Oracle数据库的运行基础，如当前的配置信息，连接到实例的会话，以及丰富而有价值的性能信息。 X$表并不是驻留在数据库文件的永久表或临时表。X$表仅仅驻留在内存中，当实例启动时，由Oracle应用程序动态创建，在内存中进行实时的维护。 它们中的大多数至少需要装载或已经打开的数据库。X$表为SYS用户所拥有，并且是只读的。 不能进行DML(更新，插入，删除)。X$表对数据库来说至关重要，所以Oracle不允许SYSDBA之外的用户直接访问，显示授权不被允许。

V$SQLTEXT：存储的是完整的SQL, 但是SQL是被分割。

V$SQLAREA：存储的SQL 和一些相关的信息，比如累计的执行次数，逻辑读，物理读等统计信息。

V$SQL：存储的是具体的SQL 和执行计划相关信息，实际上，v$sqlarea 可以看做 v$sql 根据 sqltext 等 做了 group by 之后的信息。

v$sqltext中有内存中完整的sql语句，而其他两个视图都是部分sql语句；

但v$sqltext中没有该语句的统计信息，比如执行次数等。

这几个视图的小应用：

Oracle 实时查询最耗CPU资源的SQL语句

http://blog.csdn.net/tianlesoftware/archive/2009/11/30/4898607.aspx

三. v$sql, v$sql_plan 与执行计划

有关执行计划的东西，参考我的Blog：

Oracle Explain Plan

http://blog.csdn.net/tianlesoftware/archive/2010/08/20/5827245.aspx

Oracle Optimizer CBO RBO

http://blog.csdn.net/tianlesoftware/archive/2010/08/19/5824886.aspx

实际上，看起来同样的一句SQL ，往往具有不同的执行计划, 如果是不同的数据库用户，那么相应的涉及的 对象 可能都不一样，如v$sql_plan下的：

HASH_VALUE	NUMBER	Hash value of the parent statement in the library cache. The two columns ADDRESS and HASH_VALUE can be used to join with V$SQLAREA to add the cursor-specific information.
OBJECT#	NUMBER	Object number of the table or the index
OBJECT_OWNER	VARCHAR2(30)	Name of the user who owns the schema containing the table or index
OBJECT_NAME	VARCHAR2(30)	Name of the table or index
OPTIMIZER	VARCHAR2(20)	Current mode of the optimizer for the first row in the plan (statement line), for example, CHOOSE. When the operation is a database access (for example, TABLE ACCESS), this column indicates whether or not the object is analyzed.

即使是相同的数据库用户，若 session 的优化模式、session 级的参数 等不一样，执行计划也能不同。所以即使相同的sql，也可能具有不同的执行计划。

v$sql 和 v$sql_plan就代表了具体的sql的执行计划,他们通过下面3个字段做连接：

ADDRESS RAW(4)

HASH_VALUE NUMBER

CHILD_NUMBER NUMBER

而V$SQLAREA 忽略了执行计划 等差异，只是在形式上sql文本看起来一样。相当于做了个聚合，是多个不同执行计划的sql的聚合和累计信息。

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