Find SQL that performs inefficiently in Oracle

Find SQL that performs inefficiently in Oracle

kt431128 posted 9 month ago, total 0 reviews

V$sqltext: The stored full sql,sql is split

V$sqlarea: Stored SQL and some related information, such as the cumulative number of executions, logical reading, physical reading and other statistical information (statistics)

V$sql: A SQL statement that has been resolved in a memory-shared SQL zone. Instant

SelectOpname, Target, To_char (Start_time,'YYYY-MM-DD Hh24:mi:ss') start_time, elapsed_seconds elapsed, executions execs, buffer_gets/Decode (executions,0,1, executions) bufgets, module, Sql_text fromv$session_longops SL, v$sqlarea sawhereSl.sql_hash_value=Sa.hash_value and Upper(Substr (module,1,4))<> 'RMAN' andSUBSTR (Opname,1,4)<> 'RMAN' andSl.start_time>trunc (sysdate)Order  byStart_time;

To find the full SQL statement based on the SID:

Select  from where = (Select fromwhere='&sid'    ) Order  by ASC

SelectA.cpu_time,--CPU time one out of 10,000 (microseconds)A.optimizer_mode,--Optimization MethodA.executions,--Number of executionsA.disk_reads,--read the number of diskA.sharable_mem,--How much memory is occupied by the shared poolA.buffer_gets,--number of Read buffersA.command_type,--Command Type (3:select,2:insert;6:update;7delete;47:pl/sql program unit)A.sql_text,--SQL statementsA.sharable_mem, A.persistent_mem, A.runtime_mem, A.parse_calls, A.disk_reads, A.D Irect_writes, A.concurrency_wait_time, A.user_io_wait_time fromSYS. V_$sqlarea aWHEREParsing_schema_name= 'Chea_fill'--Table Space Order  byA.cpu_timedesc

Reference: http://jenniferok.iteye.com/blog/700985

Querying the most resource-intensive queries from V$sqlarea

 select   B.username username,a.disk_reads Reads, a.executions  exec , A.disk_reads/  Decode (A.executions,0 , 1  ,a.executions) rds_exec_ratio, A.sql_text Statement  from   V$sqlarea a,dba_users b  where  a.parsing_user_id=  b.user_id  and  a.disk_reads   100000  order  by  a.disk_reads desc ; 

Replacing the Disk_reads column with the buffer_gets column gives you information about the SQL statement that consumes the most memory. V$sql: A SQL statement that has been resolved in a memory-shared SQL zone. Instant
List the 5 most frequently used queries:

Select from (select  sql_text,executions,    over     (  orderbydesc) exec_rank    fromwhere  <=5;

The SQL TOP5 that consumes the most disk reads:

Select from (select  sql_text,disk_reads,    over      (  orderbydesc) disk_reads_rank     from  where <= 5;

Find queries that require a lot of buffered read (logical read) operations:

Select from (select  sql_text,buffer_gets,    over      (  orderbydesc) buffer_gets_rank     from  where buffer_gets_rank<=5;

V$sqlarea Field Definition: http://happyhou.blog.sohu.com/60494432.html

SQL_TEXT	VARCHAR2(1000)	First thousand 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, 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, the fixed sum of all memory required during execution of all the child cursors.
SORTS	NUMBER	Sum of the number of sorts that were do for all the child cursors
VERSION_COUNT	NUMBER	Number of child cursors that is present in the cache under this parent
LOADED_VERSIONS	NUMBER	Number of child cursors that is present in the cache and has their context heap (KGL heap 6) loaded
OPEN_VERSIONS	NUMBER	The number of child cursors that is currently open under this current parent
USERS_OPENING	NUMBER	Number of users that has any of the cursors open
FETCHES	NUMBER	Number of fetches associated with the SQL statement
EXECUTIONS	NUMBER	Total number of executions, totalled through all the cursors
END_OF_FETCH_COUNT	NUMBER	Number of times this cursor is fully executed since the cursor is brought into the library cache. The value of this statistic isn't 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 be fetched before the cursor is closed or re-execute D. By definition, the value of the END_OF_FETCH_COUNT column should is less or equal to the value of the EXECUTIONS column.
USERS_EXECUTING	NUMBER	Total number of users executing the statement to 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 in 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
CONCURRENCY_WAIT_TIME	NUMBER	Concurrency Wait Time
CLUSTER_WAIT_TIME	NUMBER	Cluster Wait Time
USER_IO_WAIT_TIME	NUMBER	User I/O Wait time
PLSQL_EXEC_TIME	NUMBER	PL/SQL Execution time
JAVA_EXEC_TIME	NUMBER	Java Execution Time
ROWS_PROCESSED	NUMBER	Total number of rows processed in behalf of this SQL statement
COMMAND_TYPE	NUMBER	Oracle command Type definition
OPTIMIZER_MODE	VARCHAR2(25)	Mode under which the SQL statement was executed
PARSING_USER_ID	NUMBER	User ID of the user that have parsed the very first cursor under this parent
PARSING_SCHEMA_ID	NUMBER	Schema ID that is used to parse this child cursor
KEPT_VERSIONS	NUMBER	Number of child cursors that has been marked to being kept using the package DBMS_SHARED_POOL
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
MODULE	VARCHAR2(64)	Contains the name of the module is executing at the time that the SQL statement is first parsed as set by calling c6/>.SET_MODULE
MODULE_HASH	NUMBER	Hash value of the module is named in the MODULE column
ACTION	VARCHAR2(64)	Contains the name of the action is executing at the time that the SQL statement is first parsed as set by calling c2/>.SET_ACTION
ACTION_HASH	NUMBER	Hash value of the action that's named in the ACTION column
SERIALIZABLE_ABORTS	NUMBER	Number of times the transaction fails to serialize, producing ORA-08177 errors, totalled through all the child cursors
CPU_TIME	NUMBER	CPU time (in microseconds) used by the cursor for parsing/executing/fetching
ELAPSED_TIME	NUMBER	Elapsed time (in microseconds) used by the cursor for parsing/executing/fetching
IS_OBSOLETE	VARCHAR2(1)	Indicates whether the cursor has a become obsolete ( Y ) or not ( N ). This can happen if the number of child cursors is too large.
CHILD_LATCH	NUMBER	Child latch number which is protecting the cursor
PROGRAM_ID	NUMBER	Program Identifie

Find SQL that performs inefficiently in Oracle