oracle insertappendparallel随后查询的redo与磁盘读写
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SQL> set autotrace traceonly statistics; SQL> insert into big_table_dir_test1 select * from big_table_dir_test; 2853792 rows created. Statistics ---------------------------------------------------------- 148 recursive calls 358348 db block gets 111261 consistent gets 2 physical reads 333542568 redo size 832 bytes sent via SQL*Net to client 817 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 2 sorts (memory) 0 sorts (disk) 2853792 rows processed SQL> commit; Commit complete. SQL> select f.owner,f.object_name,f.data_object_id,count(1),max(f.data_object_id),min(f.object_id) from big_table_dir_test1 f group by f.owner,f.object_name,f.data_object_id; 2 87653 rows selected. Statistics ---------------------------------------------------------- 7 recursive calls 1 db block gets 41034 consistent gets 0 physical reads -- 传统路径insert只写buffer cache, redo保证重做 176 redo size 4428645 bytes sent via SQL*Net to client 64793 bytes received via SQL*Net from client 5845 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 87653 rows processed SQL> truncate table big_table_dir_test1; Table truncated.
SQL> insert /*+ append nologging */ into big_table_dir_test1 select * from big_table_dir_test; 2853792 rows created. Statistics ---------------------------------------------------------- 228 recursive calls 44268 db block gets 42998 consistent gets 2 physical reads 376672 redo size 827 bytes sent via SQL*Net to client 841 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 2853792 rows processed SQL> SQL> commit; Commit complete. SQL> select f.owner,f.object_name,f.data_object_id,count(1),max(f.data_object_id),min(f.object_id) from big_table_dir_test1 f group by f.owner,f.object_name,f.data_object_id; 2 87653 rows selected. Statistics ---------------------------------------------------------- 5 recursive calls 1 db block gets 40831 consistent gets 40752 physical reads --直接路径插入后，不经过buffer cache 168 redo size 4413020 bytes sent via SQL*Net to client 64793 bytes received via SQL*Net from client 5845 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 87653 rows processed SQL> SQL> / 87653 rows selected. Statistics ---------------------------------------------------------- 0 recursive calls 0 db block gets 40766 consistent gets 0 physical reads 0 redo size 4310178 bytes sent via SQL*Net to client 64793 bytes received via SQL*Net from client 5845 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 87653 rows processed
SQL> truncate table big_table_dir_test1; Table truncated. Elapsed: 00:00:00.62 SQL> SQL> alter session enable parallel dml; Session altered. Elapsed: 00:00:00.00 SQL> SQL> insert /*+ parallel(c,4) */ into big_table_dir_test1 c select * from big_table_dir_test; 2853792 rows created. Elapsed: 00:00:03.69 Statistics ---------------------------------------------------------- 13 recursive calls 2574 db block gets 43108 consistent gets 0 physical reads 119108 redo size -- insert中的parallel导致走了直接路径加载 830 bytes sent via SQL*Net to client 840 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 2853792 rows processed SQL> commit; Commit complete. SQL> select f.owner,f.object_name,f.data_object_id,count(1),max(f.data_object_id),min(f.object_id) from big_table_dir_test1 f group by f.owner,f.object_name,f.data_object_id; 2 87653 rows selected. Elapsed: 00:00:03.33 Statistics ---------------------------------------------------------- 5 recursive calls 1 db block gets 40896 consistent gets 40752 physical reads -- 没有写buffer cache 168 redo size 4470876 bytes sent via SQL*Net to client 64793 bytes received via SQL*Net from client 5845 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 87653 rows processed
SQL> truncate table big_table_dir_test1; insert into big_table_dir_test1 select /*+ parallel(b 4) */ * from big_table_dir_test b; Table truncated. Elapsed: 00:00:00.05 SQL> SQL> 2853792 rows created. Elapsed: 00:00:04.66 Statistics ---------------------------------------------------------- 139 recursive calls 358365 db block gets 110606 consistent gets 2 physical reads 333527468 redo size 846 bytes sent via SQL*Net to client 840 bytes received via SQL*Net from client 3 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 2853792 rows processed SQL> select /*+ parallel(4) */f.owner,f.object_name,f.data_object_id,count(1),max(f.data_object_id),min(f.object_id) from big_table_dir_test1 f group by f.owner,f.object_name,f.data_object_id; 2 87653 rows selected. Elapsed: 00:00:02.07 Statistics ---------------------------------------------------------- 38 recursive calls 1 db block gets 41750 consistent gets 0 physical reads -- parallel走了buffer cache 176 redo size 4557551 bytes sent via SQL*Net to client 64793 bytes received via SQL*Net from client 5845 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 87653 rows processed
目前暂时无法做到直接路径加载同时满足不生成redo，同时又写一份到buffer cache，这只能依赖于操作系统缓存，但是过多的并发append会导Disk file operations I/O致等待事件。
This event is used to wait for disk file operations (for example, open, close, seek, and resize). It is also used for miscellaneous I/O operations such as block dumps and password file accesses.
Wait Time: The wait time is the actual time it takes to do the I/O
|
Parameter |
Description |
|
FileOperation |
Type of file operation |
|
fileno |
File identification number |
|
filetype |
Type of file (for example, log file, data file, and so on) |
我们知道操作系统在操作文件的时候，需要打开文件、关闭文件、定位文件位置等，当这些操作在进行的时候，Oracle就处于等待状态。
操作系统的这些文件操作可以划分如下：
1.file creation
2 file open
3 file resize
4 file deletion
5 file close
6 wait for all aio requests to finish
7 write verification
8 wait for miscellaneous io (ftp, block dump, passwd file)
9 read from snapshot files
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