在一次周末的課程試驗中，頻繁的看到 Data file init write 等待事件。

在這里做一點記錄說明，以下是來自跟蹤文件的記錄信息：

以下是引用片段：

WAIT #2: nam='Data file init write' ela= 13031 count=1 intr=256 timeout=-1 obj#=51706

tim=6068271611

WAIT #2: nam='Data file init write' ela= 118163 count=1 intr=256 timeout=-1

obj#=51706 tim=6068392491

WAIT #2: nam='Data file init write' ela= 94036 count=1 intr=256 timeout=-1

obj#=51706 tim=6068490286

WAIT #2: nam='Data file init write' ela= 52412 count=1 intr=256 timeout=-1

obj#=51706 tim=6068545333

WAIT #2: nam='Data file init write' ela= 4 count=0 intr=32 timeout=2147483647

obj#=51706 tim=6068545596

WAIT #2: nam='Data file init write' ela= 26 count=1 intr=32 timeout=2147483647

obj#=51706 tim=6068545641

WAIT #2: nam='Data file init write' ela= 101743 count=1 intr=256 timeout=-1

obj#=51706 tim=6068648487

WAIT #2: nam='Data file init write' ela= 44854 count=1 intr=256 timeout=-1

obj#=51706 tim=6068694281

WAIT #2: nam='Data file init write' ela= 52841 count=1 intr=256 timeout=-1

obj#=51706 tim=6068748054

WAIT #2: nam='Data file init write' ela= 48984 count=1 intr=256 timeout=-1

obj#=51706 tim=6068798310

WAIT #2: nam='Data file init write' ela= 3 count=0 intr=32 timeout=2147483647

obj#=51706 tim=6068798365

WAIT #2: nam='Data file init write' ela= 26 count=1 intr=32 timeout=2147483647

obj#=51706 tim=6068798409

WAIT #2: nam='Data file init write' ela= 101899 count=1 intr=256 timeout=-1

obj#=51706 tim=6068900931

WAIT #2: nam='Data file init write' ela= 21 count=-1 intr=32 timeout=2147483647

obj#=51706 tim=6068901053

測試數(shù)據(jù)庫是Oracle10g 10.2.0.3，實際上這個等待事件也是從Oracle 10g開始引入的，用來標(biāo)識表空間或數(shù)據(jù)文件擴展時的等待。

Oracle 需要將系統(tǒng)塊格式化為Oracle數(shù)據(jù)塊，然后才能提供數(shù)據(jù)庫使用。

在這個流程處理中，Oracle經(jīng)過如下三個步驟：

1、擴展數(shù)據(jù)文件

select file# from file$ where ts#=:1

2、更新用戶空間限額

update tsq$ set blocks=:3,maxblocks=:4,grantor#=:5,priv1=:6,priv2=:7,priv3=:8 where ts#=:1 and user#=:2

3、擴展數(shù)據(jù)段

update seg$ set type#=:4,blocks=:5,extents=:6,minexts=:7,maxexts=:8,extsize=:9,extpct=:10,user#=:11,iniexts=:12,lists=decode(:13, 65535, NULL, :13),groups=decode(:14, 65535, NULL, :14), cachehint=:15, hwmincr=:16, spare1=DECODE(:17,0,NULL,:17),scanhint=:18 where ts#=:1 and file#=:2 and block#=:3

這就是Oracle10g中空間擴展時內(nèi)部流程。

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