계획 기반 동적 샘플링 실행
32419 단어 계획을 집행하다
set autotrace off
set linesize 1000
drop table t_sample purge;
create table t_sample as select * from dba_objects;
create index idx_t_sample_objid on t_sample(object_id);
select num_rows, blocks, last_analyzed
from user_tables
where table_name = 'T_SAMPLE';
NUM_ROWS BLOCKS LAST_ANALYZED
----------------------------------
-- ， 。
select index_name,
num_rows,
leaf_blocks,
distinct_keys,
last_analyzed
from user_indexes
where table_name = 'T_SAMPLE';
INDEX_NAME NUM_ROWS LEAF_BLOCKS DISTINCT_KEYS LAST_ANALYZED
------------------------------ ---------- ----------- ------------- --------------
IDX_T_SAMPLE_OBJID 73159 162 73159 11-1 -14
set autotrace traceonly
set linesize 1000
select * from t_sample where object_id=20;
----------------------------------------------------------
Plan hash value: 1453182238
--------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 207 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| T_SAMPLE | 1 | 207 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_T_SAMPLE_OBJID | 1 | | 1 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("OBJECT_ID"=20)
Note
-----
- dynamic sampling used for this statement (level=2)
----------------------------------------------------------
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
1393 bytes sent via SQL*Net to client
415 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
-- 。
select /*+dynamic_sampling(t 0) */ * from t_sample t where object_id=20;
----------------------------------------------------------
Plan hash value: 1453182238
--------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 872 | 176K| 6 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| T_SAMPLE | 872 | 176K| 6 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_T_SAMPLE_OBJID | 349 | | 1 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("OBJECT_ID"=20)
----------------------------------------------------------
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
1393 bytes sent via SQL*Net to client
415 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
-- exec dbms_stats.gather_table_stats(ownname => 'LJB',tabname => 'T_SAMPLE',estimate_percent => 10,method_opt=> 'for all indexed columns',cascade=>TRUE) ;
set autotrace off
--
select num_rows, blocks, last_analyzed
from user_tables
where table_name = 'T_SAMPLE';
NUM_ROWS BLOCKS LAST_ANALYZED
---------- ---------- --------------
73630 1068 12-1 -14
set autotrace traceonly
select * from t_sample where object_id=20;
-------------------------------------------------------------------------------------------------
Plan hash value: 1453182238
--------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 97 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| T_SAMPLE | 1 | 97 | 2 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_T_SAMPLE_OBJID | 1 | | 1 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("OBJECT_ID"=20)
----------------------------------------------------------
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
1393 bytes sent via SQL*Net to client
415 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
-- ， 。
set autotrace off
select num_rows, blocks, last_analyzed
from user_tables
where table_name = 'T';
NUM_ROWS BLOCKS LAST_ANALYZED
--------- ---------- --------------
73118 1068 11-1 -14수집되지 않았거나 오랫동안 수집되지 않은 것을 검사합니다. (표, 구역, 하위 구역)
select table_name, blocks, num_rows, last_analyzed
from user_tab_statistics t
where (t.last_analyzed is null or t.last_analyzed < sysdate - 100)
and table_name not like 'BIN$%'
order by last_analyzed ;
select table_name, blocks, num_rows, last_analyzed
from user_tab_partitions t
where (t.last_analyzed is null or t.last_analyzed < sysdate - 100)
and table_name not like 'BIN$%'
order by last_analyzed ;
select table_name, blocks, num_rows, last_analyzed
from user_tab_subpartitions t
where (t.last_analyzed is null or t.last_analyzed < sysdate - 100)
and table_name not like 'BIN$%'
order by last_analyzed ;어떤 인덱스가 수집되지 않았거나 오랫동안 수집되지 않았는지 검사하기
select t.table_name,
t.index_name,
t.blevel,
t.leaf_blocks,
t.num_rows,
t.last_analyzed
from user_ind_statistics t
where (t.last_analyzed is null or t.last_analyzed < sysdate - 100)
and table_name not like 'BIN$%'
order by table_name,index_name;임시 테이블에서 통계 정보를 수집하지 않으면 실행 계획에 오류가 발생할 수 있습니다.
수집된 통계 정보의 임시 표를 배열하여 조사하다.
select table_name,
t.last_analyzed,
t.num_rows,
t.blocks
from user_tables t
where t.temporary = 'Y'
and last_analyzed is not null;좋은 웹페이지 즐겨찾기
