Oracle性能诊断艺术-读书笔记
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create table test0605 as select * from dba_objects;
select t1.owner,t1.object_name,t1.object_id from test0605 t1 where t1.object_id=3344;
select t1.SQL_ID,t1.HASH_VALUE,t1.SQL_TEXT,t1.SQL_FULLTEXT,to_char(t1.LAST_ACTIVE_TIME,‘yyyy-mm-dd hh24:mi:ss‘) LAST_ACTIVE_TIME ,to_char(t1.LAST_LOAD_TIME,‘yyyy-mm-dd hh24:mi:ss‘) LAST_LOAD_TIME from v$sqlarea t1 where t1.SQL_FULLTEXT like ‘%test0605 t1 where t1.object_id=3344%‘
order by LAST_ACTIVE_TIME desc,LAST_LOAD_TIME desc;
/*select * from v$sql_plan t1 where t1.;
select * from v$sql_plan_statistics;
select * from v$sql_workarea;*/
select * from v$sql_plan_statistics_all t1 where t1.SQL_ID=‘f21sgfyqvkz9m‘;
select * from table(dbms_xplan.display_cursor(‘f21sgfyqvkz9m‘,0,‘advanced‘));
select * from table(dbms_xplan.display_awr(‘f21sgfyqvkz9m‘));
--1008
关于一定时期内显著的执行计划变动、资源消耗变动 ，oracle提供了awrsqrpt.sql 、spresql.sql两个脚本
--1021
1030
包含执行计划的表中的字段
基本字段
字段 描述
id 每一个操作的标识符。如果数字前面带有星号，意味着该行有谓词信息
operation 该行的操作，也叫 row source
name 操作的对象
查询优化器评估类
rows(e-rows) 评估中操作返回的记录总数
bytes(e-bytes) 评估中操作返回的字节数
tempspc 评估中操作使用的临时空间大小
cost(%cpu) 评估中操作的开销。括号中是开销的百分比。注意该值是通过执行计划计算过来的。即：父操作的开销包含子操作的开销
time 评估中执行操作需要的时间
分区类
pstart 访问的第一个分区。如果解析时不知道是哪个分区就设为key、key(i) 、key(mc)、 key(or)、 key(sq)
pstop 访问的最后一个分区。如果解析时不知道是哪个分区就设为key、key(i) 、key(mc)、 key(or)、 key(sq)
运行时统计
starts 指定操作执行的次数
a-rows 指定操作返回的真实记录数
a-time 指定操作执行的真实时间
io统计类
buffers 操作期间进行的逻辑读数量
reads 操作期间进行的物理读数量
writes 操作期间进行的物理写数量
内存使用统计类
0mem 最优执行所需内存的评估值
1mem 一次性通过(one-pass)执行所需内存的评估值
used-mem 最后一次操作时使用的内存量
user-tmp 最后一次操作时使用的临时空间大小
--1439 display函数
/*
format参数可用的基本值
basic 仅显示最少的信息。基本上之报错操作和操作的对象
typical 显示大部分相关内容，基本上包含除了别名，提纲和字段投影外的所有信息
serial 和typical类似，只是没有并行的相关信息
all 显示除了提纲外的所有信息
advanced 显示所有信息
alias 空值包含查询块名和对象别名那一部分的显示
bytes 控制执行计划表中字段bytes的显示
cost 控制执行计划表中字段cost的显示
note 控制包含注意信息note那一部分的显示
outline 控制包含提纲outline那一部分的显示
parallel 空值并行处理信息的显示，尤其是，执行计划表中字段TQ、IN-OUT、PQ distrib的显示
partition 控制分区信息的显示，尤其是pstart和pstop的显示
peek_binds 控制包含被窥测的绑定变量那一部分的显示。
predicate 控制包含谓词filter和access那一部分的显示
projection 控制包含字段投影信息那一部分的显示
remote 控制远程执行的sql语句的显示
rows 控制执行计划表中字段rows的显示
*/
--1055
--case 1
SQL> CREATE TABLE t AS SELECT * FROM o;
SQL> execute dbms_stats.gather_table_stats(user, ‘t‘)
SQL> EXPLAIN PLAN FOR CREATE TABLE t AS SELECT * FROM o;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1827057699
-------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------
| 0 | CREATE TABLE STATEMENT | | 1000 | 84000 | 5 (0)| 00:00:01 |
| 1 | LOAD AS SELECT | T | | | | |
| 2 | TABLE ACCESS FULL | O | 1000 | 84000 | 3 (0)| 00:00:01 |
-------------------------------------------------------------------------------
--case2
SQL> CREATE INDEX i ON t (object_id);
SQL>
SQL> EXPLAIN PLAN FOR ALTER INDEX i REBUILD;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1634214326
-------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------
| 0 | ALTER INDEX STATEMENT | | 1000 | 4000 | 2 (0)| 00:00:01 |
| 1 | INDEX BUILD NON UNIQUE| I | | | | |
| 2 | SORT CREATE INDEX | | 1000 | 4000 | | |
| 3 | INDEX FAST FULL SCAN| I | 1000 | 4000 | 2 (0)| 00:00:01 |
-------------------------------------------------------------------------------
--case3
SQL> EXPLAIN PLAN FOR SELECT * FROM t;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1000 | 84000 | 3 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| T | 1000 | 84000 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------
--case4
SQL> EXPLAIN PLAN FOR INSERT INTO t SELECT * FROM o WHERE rownum = 1;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1110922135
---------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | 1 | 84 | 3 (0)| 00:00:01 |
| 1 | LOAD TABLE CONVENTIONAL | T | | | | |
|* 2 | COUNT STOPKEY | | | | | |
| 3 | TABLE ACCESS FULL | O | 1000 | 84000 | 3 (0)| 00:00:01 |
---------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter(ROWNUM=1)
--case5
SQL> EXPLAIN PLAN FOR UPDATE t SET subobject_name = object_name;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 931696821
---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | 1000 | 33000 | 3 (0)| 00:00:01 |
| 1 | UPDATE | T | | | | |
| 2 | TABLE ACCESS FULL| T | 1000 | 33000 | 3 (0)| 00:00:01 |
---------------------------------------------------------------------------
--case6
SQL> EXPLAIN PLAN FOR MERGE INTO t
2 USING (SELECT * FROM o) o
3 ON (t.object_id = o.object_id)
4 WHEN MATCHED THEN UPDATE SET t.subobject_name = o.subobject_name
5 WHEN NOT MATCHED THEN INSERT (owner, object_name, object_id, created, last_ddl_time)
6 VALUES (o.owner, o.object_name, o.object_id, o.created, o.last_ddl_time);
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 4087175684
-----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------
| 0 | MERGE STATEMENT | | 1000 | 162K| 7 (15)| 00:00:01 |
| 1 | MERGE | T | | | | |
| 2 | VIEW | | | | | |
|* 3 | HASH JOIN OUTER | | 1000 | 164K| 7 (15)| 00:00:01 |
| 4 | TABLE ACCESS FULL| O | 1000 | 84000 | 3 (0)| 00:00:01 |
| 5 | TABLE ACCESS FULL| T | 1000 | 84000 | 3 (0)| 00:00:01 |
-----------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - access("T"."OBJECT_ID"(+)="O"."OBJECT_ID")
--case7
SQL> EXPLAIN PLAN FOR DELETE FROM t;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------
Plan hash value: 3335594643
---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | DELETE STATEMENT | | 1000 | 4000 | 3 (0)| 00:00:01 |
| 1 | DELETE | T | | | | |
| 2 | TABLE ACCESS FULL| T | 1000 | 4000 | 3 (0)| 00:00:01 |
---------------------------------------------------------------------------
--1519
dbms_xplan.display_cursor
/*
format可用的修饰符
allstats* 是iostats memstats的快捷方式
iostat* 控制I/0统计的显示
last* 默认，显示所有执行计划过的统计。如果指定此值，只显示最后一次执行的统计信息
memstats* 控制pga相关统计的显示
runstats_last 和iostats last 相同，适用于 oracle10g r1
runstats_tot 和iostats相同。适用于 oracle10g r1
以上附带*表示从oracle10g r2 起可以使用
*/
case1
SQL> UPDATE t
2 SET val = (SELECT /*+ index(t) */ max(val) FROM t WHERE id BETWEEN 6 AND 19),
3 pad = (SELECT pad FROM t WHERE id = 6)
4 WHERE id IN (SELECT id FROM t WHERE id BETWEEN 6 AND 19);
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(NULL,NULL,‘basic‘));
PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------------------------------------------------------------
EXPLAINED SQL STATEMENT:
------------------------
UPDATE t SET val = (SELECT /*+ index(t) */ max(val) FROM t WHERE id
BETWEEN 6 AND 19), pad = (SELECT pad FROM t WHERE id = 6) WHERE id
IN (SELECT id FROM t WHERE id BETWEEN 6 AND 19)
Plan hash value: 2674170182
----------------------------------------------
| Id | Operation | Name |
----------------------------------------------
| 0 | UPDATE STATEMENT | |
| 1 | UPDATE | T |
| 2 | NESTED LOOPS | |
| 3 | TABLE ACCESS FULL | T |
| 4 | INDEX UNIQUE SCAN | T_PK |
| 5 | SORT AGGREGATE | |
| 6 | TABLE ACCESS BY INDEX ROWID| T |
| 7 | INDEX FULL SCAN | I |
| 8 | TABLE ACCESS BY INDEX ROWID | T |
| 9 | INDEX UNIQUE SCAN | T_PK |
----------------------------------------------
--case2
SQL> SELECT deptno, count(*)
2 FROM emp
3 WHERE job = ‘CLERK‘ AND sal < 1200
4 GROUP BY deptno;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------
SQL_ID 5k3rhmx9hprh7, child number 0
-------------------------------------
SELECT deptno, count(*) FROM emp WHERE job = ‘CLERK‘ AND sal < 1200
GROUP BY deptno
Plan hash value: 4067220884
--------------------------------------------
| Id | Operation | Name | E-Rows |
--------------------------------------------
| 0 | SELECT STATEMENT | | |
| 1 | HASH GROUP BY | | 1 |
|* 2 | TABLE ACCESS FULL| EMP | 1 |
--------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter(("JOB"=‘CLERK‘ AND "SAL"<1200))
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case3
SQL> SELECT *
2 FROM emp
3 WHERE rownum <= 10;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------------------------------------
SQL_ID ajp501ttxv1vn, child number 0
-------------------------------------
SELECT * FROM emp WHERE rownum <= 10
Plan hash value: 1973284518
--------------------------------------------
| Id | Operation | Name | E-Rows |
--------------------------------------------
| 0 | SELECT STATEMENT | | |
|* 1 | COUNT STOPKEY | | |
| 2 | TABLE ACCESS FULL| EMP | 1 |
--------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=10)
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case4
SQL> SELECT *
2 FROM (
3 SELECT *
4 FROM emp
5 ORDER BY sal DESC
6 )
7 WHERE rownum <= 10;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------------------------------
SQL_ID 7jpchs5c5bstu, child number 0
-------------------------------------
SELECT * FROM ( SELECT * FROM emp ORDER BY sal DESC ) WHERE
rownum <= 10
Plan hash value: 1744961472
-------------------------------------------------
| Id | Operation | Name | E-Rows |
-------------------------------------------------
| 0 | SELECT STATEMENT | | |
|* 1 | COUNT STOPKEY | | |
| 2 | VIEW | | 1 |
|* 3 | SORT ORDER BY STOPKEY| | 1 |
| 4 | TABLE ACCESS FULL | EMP | 1 |
-------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=10)
3 - filter(ROWNUM<=10)
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case5
SQL> SELECT *
2 FROM emp
3 WHERE job = ‘CLERK‘
4 AND 1=2;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------
SQL_ID 7vajq952vnrbk, child number 0
-------------------------------------
SELECT * FROM emp WHERE job = ‘CLERK‘ AND 1=2
Plan hash value: 3896240783
--------------------------------------------
| Id | Operation | Name | E-Rows |
--------------------------------------------
| 0 | SELECT STATEMENT | | |
|* 1 | FILTER | | |
|* 2 | TABLE ACCESS FULL| EMP | 1 |
--------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(NULL IS NOT NULL)
2 - filter("JOB"=‘CLERK‘)
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case 6
SQL> SELECT ename FROM emp
2 UNION ALL
3 SELECT dname FROM dept
4 UNION ALL
5 SELECT ‘%‘ FROM dual;
ENAME
----------
ACCOUNTING
RESEARCH
SALES
OPERATIONS
%
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------------
SQL_ID 781xq971h0y2p, child number 0
-------------------------------------
SELECT ename FROM emp UNION ALL SELECT dname FROM dept UNION ALL SELECT
‘%‘ FROM dual
Plan hash value: 4181933179
--------------------------------------------
| Id | Operation | Name | E-Rows |
--------------------------------------------
| 0 | SELECT STATEMENT | | |
| 1 | UNION-ALL | | |
| 2 | TABLE ACCESS FULL| EMP | 1 |
| 3 | TABLE ACCESS FULL| DEPT | 4 |
| 4 | FAST DUAL | | 1 |
--------------------------------------------
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case7
SQL> SELECT /*+ ordered use_nl(dept) index(dept) */ *
2 FROM emp, dept
3 WHERE emp.deptno = dept.deptno
4 AND emp.comm IS NULL
5 AND dept.dname != ‘SALES‘;
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------------------
SQL_ID 3ux4g340c933p, child number 0
-------------------------------------
SELECT /*+ ordered use_nl(dept) index(dept) */ * FROM emp, dept WHERE
emp.deptno = dept.deptno AND emp.comm IS NULL AND dept.dname != ‘SALES‘
Plan hash value: 2694310824
---------------------------------------------------------
| Id | Operation | Name | E-Rows |
---------------------------------------------------------
| 0 | SELECT STATEMENT | | |
| 1 | NESTED LOOPS | | |
| 2 | NESTED LOOPS | | 1 |
|* 3 | TABLE ACCESS FULL | EMP | 1 |
|* 4 | INDEX UNIQUE SCAN | DEPT_PK | 1 |
|* 5 | TABLE ACCESS BY INDEX ROWID| DEPT | 1 |
---------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter("EMP"."COMM" IS NULL)
4 - access("EMP"."DEPTNO"="DEPT"."DEPTNO")
5 - filter("DEPT"."DNAME"<>‘SALES‘)
Note
-----
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--case 8
SQL> SELECT *
2 FROM emp
3 WHERE NOT EXISTS (SELECT /*+ no_unnest */ 0
4 FROM dept
5 WHERE dept.dname = ‘SALES‘ AND dept.deptno = emp.deptno)
6 AND NOT EXISTS (SELECT /*+ no_unnest */ 0
7 FROM bonus
8 WHERE bonus.ename = emp.ename);
FROM bonus
*
第 7 行出现错误:
ORA-00942: ？？？？？？？
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘));
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------------------
SQL_ID 2tty67sw0nz6c, child number 1
-------------------------------------
SELECT * FROM table(dbms_xplan.display_cursor(null,null,‘iostats last‘))
Plan hash value: 3713220770
---------------------------------------------------------------------
| Id | Operation | Name | E-Rows |
---------------------------------------------------------------------
| 0 | SELECT STATEMENT | | |
| 1 | COLLECTION ITERATOR PICKLER FETCH| DISPLAY_CURSOR | 52 |
---------------------------------------------------------------------
Note
-----
- cardinality feedback used for this statement
- Warning: basic plan statistics not available. These are only collected when:
* hint ‘gather_plan_statistics‘ is used for the statement or
* parameter ‘statistics_level‘ is set to ‘ALL‘, at session or system level
--1555
SQL> CREATE TABLE t
2 PARTITION BY HASH (id)
3 PARTITIONS 2
4 AS
5 SELECT rownum AS id, rownum AS n, lpad(‘*‘,1000,‘*‘) AS pad
6 FROM dual
7 CONNECT BY level <= 1000;
SQL>
SQL> PAUSE
SQL>
SQL> REM Display information about partitioning (columns Pstart and Pstop) and
SQL> REM temporary space (column TempSpc)
SQL>
SQL> SELECT /*+ gather_plan_statistics */ count(pad)
2 FROM (SELECT /* parallel(t,2) */ rownum AS rn, pad
3 FROM t
4 ORDER BY n)
5 WHERE rn = 1;
COUNT(PAD)
----------
1
SQL> /
COUNT(PAD)
----------
1
SQL> /
COUNT(PAD)
----------
1
SQL> /
COUNT(PAD)
----------
1
SQL>
SQL> SELECT * FROM table(dbms_xplan.display_cursor);
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------------------------------------
SQL_ID 6rwckvk4d8xjb, child number 0
-------------------------------------
SELECT /*+ gather_plan_statistics */ count(pad) FROM (SELECT /*
parallel(t,2) */ rownum AS rn, pad FROM t ORDER BY n) WHERE
rn = 1
Plan hash value: 2056542717
-------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Pstart| Pstop |
-------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | | 171 (100)| | | |
| 1 | SORT AGGREGATE | | 1 | 515 | | | | | |
|* 2 | VIEW | | 1177 | 591K| | 171 (2)| 00:00:02 | | |
| 3 | SORT ORDER BY | | 1177 | 591K| 640K| 171 (2)| 00:00:02 | | |
| 4 | COUNT | | | | | | | | |
| 5 | PARTITION HASH ALL| | 1177 | 591K| | 19 (0)| 00:00:01 | 1 | 2 |
| 6 | TABLE ACCESS FULL| T | 1177 | 591K| | 19 (0)| 00:00:01 | 1 | 2 |
-------------------------------------------------------------------------------------------------------
--1744
SQL> alter session set statistics_level=all;
Session altered.
执行这步之后，执行计划中才会显示 starts
select /*+ gather_plan_statistics */ * from data_skew;
select * from table(dbms_xplan.display_cursor(null,null,‘advanced‘));
select * from data_skew where rownum < 101;
--- 4dy2ffhhyud3c 569193580 0 select * from data_skew where rownum <100 1 2017/6/6 14:21:36 2017/6/6 14:21:35
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘iostats last‘));
--case 2 advanced
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘advanced‘));
--case 3 typical
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘typical‘));
--case 4 all
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘all‘));
--case 5 memstats last
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘memstats last‘));
SELECT * FROM table(dbms_xplan.display_cursor(‘6rwckvk4d8xjb‘,0,‘iostats last‘));
SELECT /*+ gather_plan_statistics */ count(pad)
FROM (SELECT /* parallel(t,2) */ rownum AS rn, pad
FROM t
ORDER BY n)
WHERE rn = 1;
grant execute on dbms_hpof to owner
dbms_profiler.
alter procedure sys.dbms_profiler.perfect_triangles compile debug;
grant all on dbms_profiler to public;
dbms_output.put_line
select t1.object_name,t1.object_id,t1.object_type,t1.owner from dba_objects t1 where t1.object_name=‘PERFECT_TRIANGLES‘;
SELECT s.line,
round(ratio_to_report(p.total_time) OVER ()*100,1) AS time,
total_occur,
s.text
FROM all_source s,
(SELECT u.unit_owner, u.unit_name, u.unit_type,
d.line#, d.total_time, d.total_occur
FROM plsql_profiler_units u, plsql_profiler_data d
WHERE u.runid = &runid
AND d.runid = u.runid
AND d.unit_number = u.unit_number) p
WHERE s.owner = p.unit_owner (+)
AND s.name = p.unit_name (+)
AND s.type = p.unit_type (+)
AND s.line = p.line# (+)
AND s.owner = user
AND s.name = ‘SLEEP‘
ORDER BY s.line;
dbms_sql.
explain plan for select * from data_skew where rownum <2000;
exec dbms_stats.gather_table_stats(user,‘DATA_SKEW‘)；
select sys_context(‘userenv‘,‘sid‘) from dual;
select * from v$sql_plan_statistics ;
select /*+ gather_plan_statistics*/ * from t where n2=19;
select sps.LAST_OUTPUT_ROWS,
sps.LAST_CR_BUFFER_GETS,
sps.LAST_CU_BUFFER_GETS
from v$session s, v$sql_plan_statistics sps
where s.prev_sql_id = sps.sql_id
and s.PREV_CHILD_NUMBER = sps.CHILD_NUMBER
and s.sid = sys_context(‘userenv‘, ‘sid‘)
and sps.OPERATION_ID = 1;
dbms_stats.ObjectTab
select * from test0605;
alter table test0605 add (tmp_obj as (substr(object_name,1,3)));
SELECT partition_name, partition_position, num_rows
FROM user_tab_partitions
WHERE table_name = ‘T‘
ORDER BY partition_position;
select p.partition_position,p.partition_name,s.subpartition_position,s.subpartition_name
from user_tab_partitions p, user_tab_subpartitions s
where p.table_name=‘T‘ and s.table_name=p.table_name and
s.partition_name=p.partition_name
order by p.partition_position,s.subpartition_position;
select * from test0605;
exec dbms_stats.gather_table_stats(user,‘TEST0605‘);
exec dbms_stats.gather_index_stats(user,‘IDX_OBJECT_ID‘);
select /*+ index(test0605 IDX_OBJECT_ID) */ object_name from test0605 where object_id =3389;
explain plan for select /*+ index_ffs(test0605 IDX_OBJECT_ID) */ object_name from test0605 where object_id is not null;
select extract(hg from sql_id) from v$sql_cs_statistics;
select owner,object_id,extract(‘SYS‘ from O) from test;
select * /*,extract(YEAR FROM CREATED)*/ from test;
select * from dba_enabled_traces;
select * from v$diag_info where name=‘‘;
select * from tvd$xtat ;
select t1.pname,t1.pval1,t1.pval2 from sys.aux_stats$ t1
where t1.sname=‘SYSSTATS_MAIN‘;
select sum(t1.SINGLEBLKRDS) as count,sum(t1.SINGLEBLKRDTIM) time_ms from v$filestat t1;
create table t as
select rownum as id,
round(dbms_random.normal*1000) as val1,
100+round(ln(rownum/3.25+2 )) as val2,
100+round(ln(rownum/3.25+2 )) as val3,
dbms_random.string(‘p‘,250) as pad
from all_objects
where rownum<=1000
order by dbms_random.value;
update t set val1=null where val1<0;
alter table t add constraints t_pk primary key(id);
create index t_val1_i on t(val1);
create index t_val2_i on t(val2);
begin
dbms_stats.gather_table_stats(
ownname=>user,
tabname=>‘T‘,
estimate_percent=>100,
method_opt =>‘for all columns size skewonly‘,
cascade=>true);
end;
select t1.NUM_ROWS,t1.BLOCKS,t1.EMPTY_BLOCKS,t1.AVG_SPACE,t1.CHAIN_CNT,t1.AVG_ROW_LEN
from user_tab_statistics t1
where t1.TABLE_NAME=‘T‘;
NUM_ROWS BLOCKS EMPTY_BLOCKS AVG_SPACE CHAIN_CNT AVG_ROW_LEN
---------- ---------- ------------ ---------- ---------- -----------
1000 44 0 0 0 266
/*
NUM_ROWS 表中数据的行数
BLOCKS 高水位线以下的数据块个数
EMPTY_BLOCKS 高水位线以上的数据块个数
AVG_SPACE 表中数据块的平均空闲空间（单位：字节）
CHAIN_CNT 涉及行迁移、行链接的总行数
AVG_ROW_LEN 表中平均每个记录的长度（单位：字节）
*/
select t1.column_name name,t1.num_distinct "#dst",t1.low_value,t1.high_value,
t1.density dens,t1.num_nulls "#null",t1.avg_col_len avglen,t1.HISTOGRAM,t1.num_buckets "#bkt"
from user_tab_col_statistics t1
where t1.table_name=‘T‘;
NAME #dst LOW_VALUE HIGH_VALUE DENS #null AVGLEN HISTOGRAM #bkt
------------------------------ ---------- ---------------------------------------------------------------- ---------------------------------------------------------------- ---------- ---------- ---------- --------------- ----------
ID 1000 C102 C20B .001 0 4 NONE 1
VAL1 457 C105 C22160 .002353264 481 3 HEIGHT BALANCED 254
VAL2 6 C20202 C20207 .0005 0 4 FREQUENCY 6
VAL3 6 C20202 C20207 .0005 0 4 FREQUENCY 6
PAD 1000 203F2C5D523371586E695D456775533C565A522A4F3128234F43502F77353026 7E7E7438735D7A464E77205B7B79454D517E384069784521344735457E2F2120 .001 0 251 HEIGHT BALANCED 254
select utl_raw.cast_to_number(low_value) as low_value,
utl_raw.cast_to_number(high_value) as high_value
from user_tab_col_statistics
where table_name=‘T‘
and column_name=‘VAL1‘;
/*
LOW_VALUE HIGH_VALUE
---------- ----------
4 3295
*/
begin
dbms_stats.gather_index_stats(ownname =>user, indname =>‘T_VAL1_I‘,estimate_percent=>100);
end;
select t1.INDEX_NAME,t1.blevel,t1.LEAF_BLOCKS,t1.DISTINCT_KEYS,
t1.NUM_ROWS,t1.CLUSTERING_FACTOR,t1.AVG_LEAF_BLOCKS_PER_KEY,t1.AVG_DATA_BLOCKS_PER_KEY
from user_ind_statistics t1
where t1.TABLE_NAME=‘T‘;
/*
INDEX_NAME BLEVEL LEAF_BLOCKS DISTINCT_KEYS NUM_ROWS CLUSTERING_FACTOR AVG_LEAF_BLOCKS_PER_KEY AVG_DATA_BLOCKS_PER_KEY
------------------------------ ---------- ----------- ------------- ---------- ----------------- ----------------------- -----------------------
T_PK 1 2 1000 1000 972 1 1
T_VAL1_I 1 2 457 519 508 1 1
T_VAL2_I 1 3 6 1000 174 1 29
BLEVEL 访问叶子快而需要读取的分支块的数量，包括根块
LEAF_BLOCKS 索引中的叶子块数量
DISTINCT_KEYS 索引中唯一键值总数
NUM_ROWS 索引中的键值数，对于主键来说 等同于 DISTINCT_KEYS
CLUSTERING_FACTOR 表明有多少临近的索引条目知道不同的数据块。
如果表中数据和索引的排序是相似的，那么 聚簇因子就小。最小值是表中非空数据的数据块总数
如果表中数据和索引的排序迥异，聚簇因子就非常大。最大值是索引中的键值数
*/
select i.index_name,i.clustering_factor,clustering_factor(user,i.table_name,ic.COLUMN_NAME) as my_clstf
from user_indexes i,user_ind_columns ic
where i.table_name=‘T‘ and i.index_name=ic.INDEX_NAME;
select * from v$fixed_table;
select * from user_tab_pending_stats;
20170531
0907
select dbms_stats.get_stats_history_retention() from dual;
select extract(hg from sql_id) from v$sql_cs_statistics;
select owner,object_id,extract(‘SYS‘ from O) from test;
select * /*,extract(YEAR FROM CREATED)*/ from test;
select * from dba_enabled_traces;
select * from v$diag_info where name=‘‘;
select * from tvd$xtat ;
select t1.pname,t1.pval1,t1.pval2 from sys.aux_stats$ t1
where t1.sname=‘SYSSTATS_MAIN‘;
select sum(t1.SINGLEBLKRDS) as count,sum(t1.SINGLEBLKRDTIM) time_ms from v$filestat t1;
create table t as
select rownum as id,
round(dbms_random.normal*1000) as val1,
100+round(ln(rownum/3.25+2 )) as val2,
100+round(ln(rownum/3.25+2 )) as val3,
dbms_random.string(‘p‘,250) as pad
from all_objects
where rownum<=1000
order by dbms_random.value;
update t set val1=null where val1<0;
alter table t add constraints t_pk primary key(id);
create index t_val1_i on t(val1);
create index t_val2_i on t(val2);
begin
dbms_stats.gather_table_stats(
ownname=>user,
tabname=>‘T‘,
estimate_percent=>100,
method_opt =>‘for all columns size skewonly‘,
cascade=>true);
end;
select t1.NUM_ROWS,t1.BLOCKS,t1.EMPTY_BLOCKS,t1.AVG_SPACE,t1.CHAIN_CNT,t1.AVG_ROW_LEN
from user_tab_statistics t1
where t1.TABLE_NAME=‘T‘;
NUM_ROWS BLOCKS EMPTY_BLOCKS AVG_SPACE CHAIN_CNT AVG_ROW_LEN
---------- ---------- ------------ ---------- ---------- -----------
1000 44 0 0 0 266
/*
NUM_ROWS 表中数据的行数
BLOCKS 高水位线以下的数据块个数
EMPTY_BLOCKS 高水位线以上的数据块个数
AVG_SPACE 表中数据块的平均空闲空间（单位：字节）
CHAIN_CNT 涉及行迁移、行链接的总行数
AVG_ROW_LEN 表中平均每个记录的长度（单位：字节）
*/
select t1.column_name name,t1.num_distinct "#dst",t1.low_value,t1.high_value,
t1.density dens,t1.num_nulls "#null",t1.avg_col_len avglen,t1.HISTOGRAM,t1.num_buckets "#bkt"
from user_tab_col_statistics t1
where t1.table_name=‘T‘;
NAME #dst LOW_VALUE HIGH_VALUE DENS #null AVGLEN HISTOGRAM #bkt
------------------------------ ---------- ---------------------------------------------------------------- ---------------------------------------------------------------- ---------- ---------- ---------- --------------- ----------
ID 1000 C102 C20B .001 0 4 NONE 1
VAL1 457 C105 C22160 .002353264 481 3 HEIGHT BALANCED 254
VAL2 6 C20202 C20207 .0005 0 4 FREQUENCY 6
VAL3 6 C20202 C20207 .0005 0 4 FREQUENCY 6
PAD 1000 203F2C5D523371586E695D456775533C565A522A4F3128234F43502F77353026 7E7E7438735D7A464E77205B7B79454D517E384069784521344735457E2F2120 .001 0 251 HEIGHT BALANCED 254
select utl_raw.cast_to_number(low_value) as low_value,
utl_raw.cast_to_number(high_value) as high_value
from user_tab_col_statistics
where table_name=‘T‘
and column_name=‘VAL1‘;
/*
LOW_VALUE HIGH_VALUE
---------- ----------
4 3295
*/
begin
dbms_stats.gather_index_stats(ownname =>user, indname =>‘T_VAL1_I‘,estimate_percent=>100);
end;
select t1.INDEX_NAME,t1.blevel,t1.LEAF_BLOCKS,t1.DISTINCT_KEYS,
t1.NUM_ROWS,t1.CLUSTERING_FACTOR,t1.AVG_LEAF_BLOCKS_PER_KEY,t1.AVG_DATA_BLOCKS_PER_KEY
from user_ind_statistics t1
where t1.TABLE_NAME=‘T‘;
/*
INDEX_NAME BLEVEL LEAF_BLOCKS DISTINCT_KEYS NUM_ROWS CLUSTERING_FACTOR AVG_LEAF_BLOCKS_PER_KEY AVG_DATA_BLOCKS_PER_KEY
------------------------------ ---------- ----------- ------------- ---------- ----------------- ----------------------- -----------------------
T_PK 1 2 1000 1000 972 1 1
T_VAL1_I 1 2 457 519 508 1 1
T_VAL2_I 1 3 6 1000 174 1 29
BLEVEL 访问叶子快而需要读取的分支块的数量，包括根块
LEAF_BLOCKS 索引中的叶子块数量
DISTINCT_KEYS 索引中唯一键值总数
NUM_ROWS 索引中的键值数，对于主键来说 等同于 DISTINCT_KEYS
CLUSTERING_FACTOR 表明有多少临近的索引条目知道不同的数据块。
如果表中数据和索引的排序是相似的，那么 聚簇因子就小。最小值是表中非空数据的数据块总数
如果表中数据和索引的排序迥异，聚簇因子就非常大。最大值是索引中的键值数
*/
select i.index_name,i.clustering_factor,clustering_factor(user,i.table_name,ic.COLUMN_NAME) as my_clstf
from user_indexes i,user_ind_columns ic
where i.table_name=‘T‘ and i.index_name=ic.INDEX_NAME;
select * from v$fixed_table;
select * from user_tab_pending_stats;
20170531
0907
--统计信息保留窗口
select dbms_stats.get_stats_history_retention() from dual;
--2.0 修改保留窗口
exec dbms_stats.alter_stats_history_retention(retention=>14);
--3.0 删除14t天之前的统计信息
dbms_stats.purge_stats(before_timestamp=>systimestamp-14);
--执行 2.0 3.0 需要权限 analyze any dictionary
--4.0 确认统计信息是否变动过
select t1.OWNER,t1.TABLE_NAME，to_char(t1.STATS_UPDATE_TIME,‘yyyy-mm-dd hh24:mi:ss‘) stats_time from dba_tab_stats_history t1 where t1.owner=‘OWNER‘ and t1.TABLE_NAME=‘T1‘ order by stats_time desc;
--5.0 恢复单张表的统计信息
dbms_stats.restore_table_stats(ownname=>,
tabname=>,
as_of_timestamp=>,
force=>)
--6.0 修改表的统计信息
exec dbms_stats.gather_table_stats(ownname=>‘OWNER‘,tabname=>‘T1‘);
select wri.rowcnt,
wri.blkcnt,
wri.avgrln,
wri.analyzetime from sys.wri$_optstat_tab_history wri,dba_objects obj where wri.obj#=obj.data_object_id
and obj.object_name=‘T1‘
order by wri.analyzetime desc nulls last,obj.subobject_name asc nulls last,
obj.data_object_id desc nulls last;
select count(1) from test t1 ;
--71988
select t1.owner,t1.object_name from test t1 where t1.object_id =3389;
SQL> exec dbms_stats.set_table_stats( tabname=>‘T1‘,ownname=>‘OWNER‘,numrows => 2);
PL/SQL procedure successfully completed.
select t1.operation,to_char(t1.START_TIME,‘yyyy-mm-dd hh24:mi:ss‘), (t1.end_time-t1.start_time) day(1) to second(0) as duration
from dba_optstat_operations t1
order by t1.start_time desc;
--1528 去人该参数maximum PGA allocated 如果 远远大于 aggregate PGA target parameter ，那么初始化参数 pga_aggregate_target 值 也许不合适了
select name ,value/1024/1024 ,unit from v$pgastat where name in (‘aggregate PGA target parameter‘,‘maximum PGA allocated‘)
--1559
select * from v$sql_plan t1;
select * from v$sql_plan_statistics t1;
select * from v$sql_workarea t1;
select * from v$sql_plan_statistics_all;
--10053 events
alter session set tracefile_identifier=‘10053‘;
alter session set events ‘10053 trace name context forever,level 1‘;
select * from test;
alter session set events ‘10053 trace name context off‘;
--10132 events
alter session set tracefile_identifier=‘10132‘;
alter session set events ‘10132 trace name context forever,level 1‘;
select * from test;
alter session set events ‘10132 trace name context off‘;
--1609 历史执行计划
select * from table(dbms_xplan.display_awr(‘sql_id‘))
--1639
为了使用 display_cursor函数，调用者必须对以下几张动态性能视图有 select权限： V$SESSION 、v$sql、v$sql_plan、v$sql_plan_statistics_all
20170601
select * from scott.emp where deptno=10 order by ename;
select * from table(dbms_xplan.display(null,null,‘advanced‘));
select * from table(dbms_xplan.display(null,null,‘advanced +iostats last‘));
/*
1 Plan hash value: 150391907
2
3 ---------------------------------------------------------------------------
4 | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
5 ---------------------------------------------------------------------------
6 | 0 | SELECT STATEMENT | | 5 | 190 | 4 (25)| 00:00:01 |
7 | 1 | SORT ORDER BY | | 5 | 190 | 4 (25)| 00:00:01 |
8 |* 2 | TABLE ACCESS FULL| EMP | 5 | 190 | 3 (0)| 00:00:01 |
9 ---------------------------------------------------------------------------
10
11 Predicate Information (identified by operation id):
12 ---------------------------------------------------
13
14 2 - filter("DEPTNO"=10)
*/
1030
包含执行计划的表中的字段
基本字段
字段 描述
id 每一个操作的标识符。如果数字前面带有星号，意味着该行有谓词信息
operation 该行的操作，也叫 row source
name 操作的对象
查询优化器评估类
rows(e-rows) 评估中操作返回的记录总数
bytes(e-bytes) 评估中操作返回的字节数
tempspc 评估中操作使用的临时空间大小
cost(%cpu) 评估中操作的开销。括号中是开销的百分比。注意该值是通过执行计划计算过来的。即：福操作的开销包含子操作的开销
time 评估中执行操作需要的时间
分区类
pstart 访问的第一个分区。如果解析时不知道是哪个分区就设为key、key(i) 、key(mc)、 key(or)、 key(sq)
pstop 访问的最后一个分区。如果解析时不知道是哪个分区就设为key、key(i) 、key(mc)、 key(or)、 key(sq)
并行和分布式处理类
starts 指定操作执行的次数
a-rows 指定操作返回的真实记录数
a-time 指定操作执行的真实时间
io统计类
buffers 操作期间进行的逻辑读数量
reads 操作期间进行的物理读数量
writes 操作期间进行的物理写数量
内存使用统计类
omem 最有执行所需内存的评估值
imem 一次性通过(one-pass)执行所需内存的评估值
used-mem 最后一次操作时使用的内存量
user-tmp 最后一次操作时使用的临时空间大小
select * from scott.emp where rownum <5;
select * from table(dbms_xplan.display(null,null,‘advanced +allstats‘));
select * from table(dbms_xplan.display(null,null,‘advanced +iostats‘));
select * from table(dbms_xplan.display(null,null,‘advanced +last‘));
select * from table(dbms_xplan.display(null,null,‘advanced +memstats‘));
select * from table(dbms_xplan.display(null,null,‘advanced +runstats_last‘));
select * from (select * from scott.emp order by sal desc) where rownum <6;
select * from table(dbms_xplan.display(null,null,‘advanced‘));
select * from scott.emp,scott.dept where emp.deptno=dept.deptno and emp.comm is null and dept.dname!=‘SALeES‘;
select t1.INDEX_NAME,t1.blevel,t1.LEAF_BLOCKS,t1.DISTINCT_KEYS,
t1.NUM_ROWS,t1.CLUSTERING_FACTOR,t1.AVG_LEAF_BLOCKS_PER_KEY,t1.AVG_DATA_BLOCKS_PER_KEY
from user_ind_statistics t1
where t1.TABLE_NAME=‘TEST‘;
SELECT index_name, clustering_factor(user, table_name, column_name) AS clust_factor FROM user_ind_columns WHERE table_name = ‘T‘;
select * from sys.aux_stats_history;
--SQL> REM Display information about execution statistics (columns Starts, E-Rows,
--SQL> REM A-Rows and A-Time) and I/O operations (columns Buffers, Reads and Writes)
--1. 确认该参数statistics_level 的值
SQL> show parameter statistics_level;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
statistics_level string TYPICAL --该参数statistics_level默认值 typical
--2. 修改参数值为 all
SQL> alter session set statistics_level=all;
Session altered.
--3. 再次确认该参数值
SQL> show parameter statistics_level;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
statistics_level string ALL
/*
执行计划中 Starts 、 E-Rows 、A-Rows 、 A-Time 、Buffers 、 Reads 、 Writes 等参数只在 statistics_level=all的情况下才可以看到值。
*/
--以下开始测试
select * from data_skew;
以下分为 case1、case2、case3、case4、case5
--case 1 iostats last
SELECT * FROM table(dbms_xplan.display_cursor(‘4y4a4kxntcmsf‘,0,‘iostats last‘));
/*
1 SQL_ID 6rwckvk4d8xjb, child number 0
2 -------------------------------------
3 SELECT \*+ gather_plan_statistics *\ count(pad) FROM (SELECT \*
4 parallel(t,2) *\ rownum AS rn, pad FROM t ORDER BY n) WHERE
5 rn = 1
6
7 Plan hash value: 2056542717
8
9 -----------------------------------------------------------------------------------------------------------
10 | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes |
11 -----------------------------------------------------------------------------------------------------------
12 | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.03 | 153 | 126 | 126 |
13 | 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.03 | 153 | 126 | 126 |
14 |* 2 | VIEW | | 1 | 894 | 1 |00:00:00.03 | 153 | 126 | 126 |
15 | 3 | SORT ORDER BY | | 1 | 894 | 1000 |00:00:00.04 | 153 | 126 | 126 |
16 | 4 | COUNT | | 1 | | 1000 |00:00:00.01 | 150 | 0 | 0 |
17 | 5 | PARTITION HASH ALL| | 1 | 894 | 1000 |00:00:00.01 | 150 | 0 | 0 |
18 | 6 | TABLE ACCESS FULL| T | 2 | 894 | 1000 |00:00:00.01 | 150 | 0 | 0 |
19 -----------------------------------------------------------------------------------------------------------
20
21 Predicate Information (identified by operation id):
22 ---------------------------------------------------
23
24 2 - filter("RN"=1)
25
26 Note
27 -----
28 - dynamic sampling used for this statement (level=2)
29
*/
--case 2 advanced
SELECT * FROM table(dbms_xplan.display_cursor(‘cahbf3stcpj2g‘,0,‘advanced‘));
/*
1 SQL_ID 6rwckvk4d8xjb, child number 0
2 -------------------------------------
3 SELECT \*+ gather_plan_statistics *\ count(pad) FROM (SELECT \*
4 parallel(t,2) *\ rownum AS rn, pad FROM t ORDER BY n) WHERE
5 rn = 1
6
7 Plan hash value: 2056542717
8
9 -------------------------------------------------------------------------------------------------------
10 | Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Pstart| Pstop |
11 -------------------------------------------------------------------------------------------------------
12 | 0 | SELECT STATEMENT | | | | | 139 (100)| | | |
13 | 1 | SORT AGGREGATE | | 1 | 515 | | | | | |
14 |* 2 | VIEW | | 894 | 449K| | 139 (2)| 00:00:01 | | |
15 | 3 | SORT ORDER BY | | 894 | 449K| 488K| 139 (2)| 00:00:01 | | |
16 | 4 | COUNT | | | | | | | | |
17 | 5 | PARTITION HASH ALL| | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
18 | 6 | TABLE ACCESS FULL| T | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
19 -------------------------------------------------------------------------------------------------------
20
21 Query Block Name / Object Alias (identified by operation id):
22 -------------------------------------------------------------
23
24 1 - SEL$1
*/
--case 3 typical
SELECT * FROM table(dbms_xplan.display_cursor(‘cahbf3stcpj2g‘,0,‘typical‘));
/*
1 SQL_ID 6rwckvk4d8xjb, child number 0
2 -------------------------------------
3 SELECT \*+ gather_plan_statistics *\ count(pad) FROM (SELECT \*
4 parallel(t,2) *\ rownum AS rn, pad FROM t ORDER BY n) WHERE
5 rn = 1
6
7 Plan hash value: 2056542717
8
9 -------------------------------------------------------------------------------------------------------
10 | Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Pstart| Pstop |
11 -------------------------------------------------------------------------------------------------------
12 | 0 | SELECT STATEMENT | | | | | 139 (100)| | | |
13 | 1 | SORT AGGREGATE | | 1 | 515 | | | | | |
14 |* 2 | VIEW | | 894 | 449K| | 139 (2)| 00:00:01 | | |
15 | 3 | SORT ORDER BY | | 894 | 449K| 488K| 139 (2)| 00:00:01 | | |
16 | 4 | COUNT | | | | | | | | |
17 | 5 | PARTITION HASH ALL| | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
18 | 6 | TABLE ACCESS FULL| T | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
19 -------------------------------------------------------------------------------------------------------
20
21 Predicate Information (identified by operation id):
22 ---------------------------------------------------
23
24 2 - filter("RN"=1)
25
26 Note
27 -----
28 - dynamic sampling used for this statement (level=2)
29
*/
--case 4 all
SELECT * FROM table(dbms_xplan.display_cursor(‘cahbf3stcpj2g‘,0,‘all‘));
/*
1 SQL_ID 6rwckvk4d8xjb, child number 0
2 -------------------------------------
3 SELECT \*+ gather_plan_statistics *\ count(pad) FROM (SELECT \*
4 parallel(t,2) *\ rownum AS rn, pad FROM t ORDER BY n) WHERE
5 rn = 1
6
7 Plan hash value: 2056542717
8
9 -------------------------------------------------------------------------------------------------------
10 | Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Pstart| Pstop |
11 -------------------------------------------------------------------------------------------------------
12 | 0 | SELECT STATEMENT | | | | | 139 (100)| | | |
13 | 1 | SORT AGGREGATE | | 1 | 515 | | | | | |
14 |* 2 | VIEW | | 894 | 449K| | 139 (2)| 00:00:01 | | |
15 | 3 | SORT ORDER BY | | 894 | 449K| 488K| 139 (2)| 00:00:01 | | |
16 | 4 | COUNT | | | | | | | | |
17 | 5 | PARTITION HASH ALL| | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
18 | 6 | TABLE ACCESS FULL| T | 894 | 449K| | 19 (0)| 00:00:01 | 1 | 2 |
19 -------------------------------------------------------------------------------------------------------
20
21 Query Block Name / Object Alias (identified by operation id):
22 -------------------------------------------------------------
23
24 1 - SEL$1
25 2 - SEL$2 / [email protected]$1
26 3 - SEL$2
27 6 - SEL$2 / [email protected]$2
28
29 Predicate Information (identified by operation id):
30 ---------------------------------------------------
31
32 2 - filter("RN"=1)
33
34 Column Projection Information (identified by operation id):
35 -----------------------------------------------------------
36
37 1 - (#keys=0) COUNT("PAD")[22]
38 2 - "RN"[NUMBER,22], "PAD"[VARCHAR2,1000]
39 3 - (#keys=1) "N"[NUMBER,22], ROWNUM[22], "PAD"[VARCHAR2,1000]
40 4 - "N"[NUMBER,22], "PAD"[VARCHAR2,1000], ROWNUM[4]
41 5 - "N"[NUMBER,22], "PAD"[VARCHAR2,1000]
42 6 - "N"[NUMBER,22], "PAD"[VARCHAR2,1000]
43
44 Note
45 -----
46 - dynamic sampling used for this statement (level=2)
47
*/
--case 5 memstats last
SELECT * FROM table(dbms_xplan.display_cursor(‘cahbf3stcpj2g‘,0,‘memstats last‘));
/*
1 SQL_ID 6rwckvk4d8xjb, child number 0
2 -------------------------------------
3 SELECT \*+ gather_plan_statistics *\ count(pad) FROM (SELECT \*
4 parallel(t,2) *\ rownum AS rn, pad FROM t ORDER BY n) WHERE
5 rn = 1
6
7 Plan hash value: 2056542717
8
9 --------------------------------------------------------------------------------------------------------------------
10 | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | OMem | 1Mem | Used-Mem | Used-Tmp|
11 --------------------------------------------------------------------------------------------------------------------
12 | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.03 | | | | |
13 | 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.03 | | | | |
14 |* 2 | VIEW | | 1 | 894 | 1 |00:00:00.03 | | | | |
15 | 3 | SORT ORDER BY | | 1 | 894 | 1000 |00:00:00.04 | 1134K| 560K|74752 (1)| 1024 |
16 | 4 | COUNT | | 1 | | 1000 |00:00:00.01 | | | | |
17 | 5 | PARTITION HASH ALL| | 1 | 894 | 1000 |00:00:00.01 | | | | |
18 | 6 | TABLE ACCESS FULL| T | 2 | 894 | 1000 |00:00:00.01 | | | | |
19 --------------------------------------------------------------------------------------------------------------------
20
21 Predicate Information (identified by operation id):
22 ---------------------------------------------------
23
24 2 - filter("RN"=1)
25
26 Note
27 -----
28 - dynamic sampling used for this statement (level=2)
29
*/
/*
添加 hint /*+ gather_plan_statistics */
SELECT * FROM table(dbms_xplan.display_cursor(NULL,NULL,‘runstats_last‘));
以 runstats_last的方式查看执行计划 同样可以返回 execution statistics (columns Starts, E-Rows,
SQL> REM A-Rows and A-Time) and I/O operations (columns Buffers, Reads and Writes)
*/
select /*+ gather_plan_statistics */ object_name from test0605;
select * from table(dbms_xplan.display_cursor(null,null,‘advanced‘));
select * from test0605;
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