oracle 回收站(recyclebin)引起的性能问题
检查最近的数据库AWR报告，发现有一条系统的SQL非常慢，执行一次接近37s，把SQL弄出来执行了一下，发现问题出在回收站，回收站中有1万3千张表，清理之后，运行此条SQL只需要0.46s。我想影响的SQL不仅仅是这一条，相关调用数据字典的功能都会有好处。
| 109 | 13 | 3 | 36.49 | 1.94 | fk8ncdwta6fx2 | JDBC Thin Client | SELECT a.tablespace_name "Tabl... |
SQL> set linesize 300
SQL> set autotrace traceonlySQL> set timing on
SQL> SELECT a.tablespace_name "Tablespace_name",
2 total "Total",
3 free "Free",
4 ROUND(free / total, 4) * 100 "%free"
5 FROM (SELECT tablespace_name, SUM(bytes) free
6 FROM DBA_FREE_SPACE
7 GROUP BY tablespace_name) a,
8 (SELECT tablespace_name, SUM(bytes) total
9 FROM DBA_DATA_FILES
10 GROUP BY tablespace_name) b
11 WHERE a.tablespace_name = b.tablespace_name;
已选择7行。
已用时间: 00: 00: 34.50
执行计划
----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|
----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1298 | 77880 | 171K(100)|
| 1 | MERGE JOIN | | 1298 | 77880 | 171K(100)|
| 2 | SORT JOIN | | 64916 | 1901K| 171K(100)|
| 3 | VIEW | | 64916 | 1901K| 171K(100)|
| 4 | HASH GROUP BY | | 64916 | 1901K| 171K(100)|
| 5 | VIEW | DBA_FREE_SPACE | 64916 | 1901K| 171K(100)|
| 6 | UNION-ALL | | | | |
| 7 | NESTED LOOPS | | 1 | 63 | 4 (0)|
| 8 | NESTED LOOPS | | 1 | 45 | 3 (0)|
| 9 | TABLE ACCESS FULL | FET$ | 1 | 39 | 3 (0)|
| 10 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 11 | TABLE ACCESS CLUSTER | TS$ | 1 | 18 | 1 (0)|
| 12 | NESTED LOOPS | | 82 | 5658 | 4 (0)|
| 13 | NESTED LOOPS | | 82 | 5166 | 4 (0)|
| 14 | TABLE ACCESS FULL | TS$ | 7 | 168 | 4 (0)|
| 15 | FIXED TABLE FIXED INDEX | X$KTFBFE (ind:1) | 13 | 507 | 0 (0)|
| 16 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 17 | NESTED LOOPS | | 64832 | 6774K| 171K(100)|
| 18 | NESTED LOOPS | | 91493 | 9024K| 171K(100)|
| 19 | HASH JOIN | | 13456 | 473K| 107 (1)|
| 20 | TABLE ACCESS FULL | RECYCLEBIN$ | 14707 | 172K| 103 (1)|
| 21 | TABLE ACCESS FULL | TS$ | 7 | 168 | 4 (0)|
| 22 | FIXED TABLE FIXED INDEX | X$KTFBUE (ind:1) | 7 | 455 | 13 (100)|
| 23 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 24 | NESTED LOOPS | | 1 | 88 | 16 (0)|
| 25 | NESTED LOOPS | | 1 | 70 | 15 (0)|
| 26 | NESTED LOOPS | | 1 | 58 | 14 (0)|
| 27 | TABLE ACCESS FULL | UET$ | 1 | 52 | 14 (0)|
| 28 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 29 | TABLE ACCESS BY INDEX ROWID | RECYCLEBIN$ | 1 | 12 | 1 (0)|
| 30 | INDEX RANGE SCAN | RECYCLEBIN$_TS | 7354 | | 1 (0)|
| 31 | TABLE ACCESS CLUSTER | TS$ | 1 | 18 | 1 (0)|
| 32 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
| 33 | SORT JOIN | | 2 | 60 | 6 (34)|
| 34 | VIEW | | 2 | 60 | 5 (20)|
| 35 | HASH GROUP BY | | 2 | 60 | 5 (20)|
| 36 | VIEW | DBA_DATA_FILES | 2 | 60 | 4 (0)|
| 37 | UNION-ALL | | | | |
| 38 | NESTED LOOPS | | 1 | 356 | 2 (0)|
| 39 | NESTED LOOPS | | 1 | 342 | 1 (0)|
| 40 | NESTED LOOPS | | 1 | 329 | 1 (0)|
| 41 | FIXED TABLE FULL | X$KCCFN | 1 | 310 | 0 (0)|
| 42 | TABLE ACCESS BY INDEX ROWID| FILE$ | 1 | 19 | 1 (0)|
| 43 | INDEX UNIQUE SCAN | I_FILE1 | 1 | | 0 (0)|
| 44 | FIXED TABLE FIXED INDEX | X$KCCFE (ind:1) | 4 | 52 | 0 (0)|
| 45 | TABLE ACCESS CLUSTER | TS$ | 1 | 14 | 1 (0)|
| 46 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
| 47 | NESTED LOOPS | | 1 | 399 | 2 (0)|
| 48 | NESTED LOOPS | | 1 | 385 | 1 (0)|
| 49 | NESTED LOOPS | | 1 | 372 | 1 (0)|
| 50 | NESTED LOOPS | | 1 | 362 | 0 (0)|
| 51 | FIXED TABLE FULL | X$KCCFN | 1 | 310 | 0 (0)|
| 52 | FIXED TABLE FIXED INDEX | X$KTFBHC (ind:1) | 1 | 52 | 0 (0)|
| 53 | TABLE ACCESS BY INDEX ROWID| FILE$ | 1 | 10 | 1 (0)|
| 54 | INDEX UNIQUE SCAN | I_FILE1 | 1 | | 0 (0)|
| 55 | FIXED TABLE FIXED INDEX | X$KCCFE (ind:1) | 4 | 52 | 0 (0)|
| 56 | TABLE ACCESS CLUSTER | TS$ | 1 | 14 | 1 (0)|
| 57 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
----------------------------------------------------------------------------------------------
Note
-----
- 'PLAN_TABLE' is old version
统计信息
----------------------------------------------------------
344711 recursive calls
316 db block gets
65610 consistent gets
15018 physical reads
0 redo size
496 bytes sent via SQL*Net to client
239 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
7 rows processed
执行purge recyclebin; 后
SQL> /
已选择7行。
已用时间: 00: 00: 00.46
执行计划
----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|
----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1298 | 77880 | 171K(100)|
| 1 | MERGE JOIN | | 1298 | 77880 | 171K(100)|
| 2 | SORT JOIN | | 64916 | 1901K| 171K(100)|
| 3 | VIEW | | 64916 | 1901K| 171K(100)|
| 4 | HASH GROUP BY | | 64916 | 1901K| 171K(100)|
| 5 | VIEW | DBA_FREE_SPACE | 64916 | 1901K| 171K(100)|
| 6 | UNION-ALL | | | | |
| 7 | NESTED LOOPS | | 1 | 63 | 4 (0)|
| 8 | NESTED LOOPS | | 1 | 45 | 3 (0)|
| 9 | TABLE ACCESS FULL | FET$ | 1 | 39 | 3 (0)|
| 10 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 11 | TABLE ACCESS CLUSTER | TS$ | 1 | 18 | 1 (0)|
| 12 | NESTED LOOPS | | 82 | 5658 | 4 (0)|
| 13 | NESTED LOOPS | | 82 | 5166 | 4 (0)|
| 14 | TABLE ACCESS FULL | TS$ | 7 | 168 | 4 (0)|
| 15 | FIXED TABLE FIXED INDEX | X$KTFBFE (ind:1) | 13 | 507 | 0 (0)|
| 16 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 17 | NESTED LOOPS | | 64832 | 6774K| 171K(100)|
| 18 | NESTED LOOPS | | 91493 | 9024K| 171K(100)|
| 19 | HASH JOIN | | 13456 | 473K| 107 (1)|
| 20 | TABLE ACCESS FULL | RECYCLEBIN$ | 14707 | 172K| 103 (1)|
| 21 | TABLE ACCESS FULL | TS$ | 7 | 168 | 4 (0)|
| 22 | FIXED TABLE FIXED INDEX | X$KTFBUE (ind:1) | 7 | 455 | 13 (100)|
| 23 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 24 | NESTED LOOPS | | 1 | 88 | 16 (0)|
| 25 | NESTED LOOPS | | 1 | 70 | 15 (0)|
| 26 | NESTED LOOPS | | 1 | 58 | 14 (0)|
| 27 | TABLE ACCESS FULL | UET$ | 1 | 52 | 14 (0)|
| 28 | INDEX UNIQUE SCAN | I_FILE2 | 1 | 6 | 0 (0)|
| 29 | TABLE ACCESS BY INDEX ROWID | RECYCLEBIN$ | 1 | 12 | 1 (0)|
| 30 | INDEX RANGE SCAN | RECYCLEBIN$_TS | 7354 | | 1 (0)|
| 31 | TABLE ACCESS CLUSTER | TS$ | 1 | 18 | 1 (0)|
| 32 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
| 33 | SORT JOIN | | 2 | 60 | 6 (34)|
| 34 | VIEW | | 2 | 60 | 5 (20)|
| 35 | HASH GROUP BY | | 2 | 60 | 5 (20)|
| 36 | VIEW | DBA_DATA_FILES | 2 | 60 | 4 (0)|
| 37 | UNION-ALL | | | | |
| 38 | NESTED LOOPS | | 1 | 356 | 2 (0)|
| 39 | NESTED LOOPS | | 1 | 342 | 1 (0)|
| 40 | NESTED LOOPS | | 1 | 329 | 1 (0)|
| 41 | FIXED TABLE FULL | X$KCCFN | 1 | 310 | 0 (0)|
| 42 | TABLE ACCESS BY INDEX ROWID| FILE$ | 1 | 19 | 1 (0)|
| 43 | INDEX UNIQUE SCAN | I_FILE1 | 1 | | 0 (0)|
| 44 | FIXED TABLE FIXED INDEX | X$KCCFE (ind:1) | 4 | 52 | 0 (0)|
| 45 | TABLE ACCESS CLUSTER | TS$ | 1 | 14 | 1 (0)|
| 46 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
| 47 | NESTED LOOPS | | 1 | 399 | 2 (0)|
| 48 | NESTED LOOPS | | 1 | 385 | 1 (0)|
| 49 | NESTED LOOPS | | 1 | 372 | 1 (0)|
| 50 | NESTED LOOPS | | 1 | 362 | 0 (0)|
| 51 | FIXED TABLE FULL | X$KCCFN | 1 | 310 | 0 (0)|
| 52 | FIXED TABLE FIXED INDEX | X$KTFBHC (ind:1) | 1 | 52 | 0 (0)|
| 53 | TABLE ACCESS BY INDEX ROWID| FILE$ | 1 | 10 | 1 (0)|
| 54 | INDEX UNIQUE SCAN | I_FILE1 | 1 | | 0 (0)|
| 55 | FIXED TABLE FIXED INDEX | X$KCCFE (ind:1) | 4 | 52 | 0 (0)|
| 56 | TABLE ACCESS CLUSTER | TS$ | 1 | 14 | 1 (0)|
| 57 | INDEX UNIQUE SCAN | I_TS# | 1 | | 0 (0)|
----------------------------------------------------------------------------------------------
Note
-----
- 'PLAN_TABLE' is old version
统计信息
----------------------------------------------------------
19073 recursive calls
308 db block gets
5429 consistent gets
826 physical reads
0 redo size
514 bytes sent via SQL*Net to client
239 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
7 rows processed