WAIT #140324703611992: nam='db file sequential read' ela= 12 file#=4 block#=786 blocks=1 obj#=90538 tim=1521769053619554 WAIT #140324703611992: nam='db file sequential read' ela= 10 file#=4 block#=1214 blocks=1 obj#=90538 tim=1521769053619677 WAIT #140324703611992: nam='db file sequential...
SQL>selectevent#,name,parameter1,parameter2,parameter3fromv$event_namewherename='db file parallel read'; EVENT# NAME PARAMETER1 PARAMETER2 PARAMETER3--- --- --- --- ---120dbfileparallelreadfiles blocks requests 1. db file parallel read Contrary to what the name suggests, the db file par...
The process has issued multiple I/O requests in parallel to read blocks from data files into memory and is waiting for all requests to complete. This occurs during regular activity when a session batches many single block I/O requests together and issues them in parallel. This is also occurs...
db file parallel read等待事件 The process has issued multiple I/O requests in parallel to read blocks from data files into memory and is waiting for all requests to complete. This occurs during regular activity when a session batches many single block I/O requests together and issues them in ...
from v$session_wait where event = 'db file parallel read'; 优化该等待事件的手段可以参考优化db file sequential read等待事件中非SQL优化方法部分。 3.2.4 direct path read & direct path read (lob) 当直接读取(Direct Read)数据到PGA(而不是到Buffer Cache)中去时,会发生Direct Path Read等待事件。对Lo...
db file parallel read 60 44.51 #會話2 & 會話3 begin for i in 1..100000 loop execute immediate 'insert into test_wait3(row_no) values ('||i||')'; commit; end loop; end; / #會話1 SQL> select event,TOTAL_WAITS,AVERAGE_WAIT from v$system_event where upper(event) like 'DB FILE%...
●【等待事件】User I/O类 等待事件(2.2)--db file scattered read(数据文件离散读) SELECT* FROM v$event_name WHERE NAME IN('db file parallel read'); 在V$SESSION_WAIT这个视图里面,这个等待事件有三个参数P1、P2、P3,其中P1为files代表有多少个文件被读取所请求,P2为blocks代表总共有多少个BLOCK被请求...
Wait Time:Wait until all of the I/Os are completed 解释: db file parallel read这在恢复期间发生。它也可能在缓冲区预取期间发生,作为优化(而不是执行多个单块读取)。从数据库并行读取需要作为恢复一部分进行更改的数据库块。
l direct path read l direct path write (2)控制文件I/O相关的等待事件: l control file parallel write l control file sequential read l control file single write (3)Redo日志文件I/O相关的等待事件: l log file parallel write l log file sync ...
SQL>alter system flush buffer_cache;SQL>selectevent,TOTAL_WAITS,AVERAGE_WAITfromv$system_eventwhereupper(event)like'DB FILE%';EVENTTOTAL_WAITSAVERAGE_WAITdb file sequential read190301.32db file scattered read12162.06db file single write120.17db file parallel read88.54create index ind_t4_01 ont4(row...