Tuesday Mar 19, 2013

利用44951 event解决LOB SPACE enq HW – contention等待争用

对存有LOB大对象的表的并发插入、更新引起的LOB Segment High Water Mark是常见的LOb并发争用; 特别是在ASSM(Auto Segment Space Management)的表空间上这种LOB的HWM可能比MSSM(Manual Segment Space Management)更为严重,其原因是在MSSM下LOB的HWM bump一次会获取128个chunk, 而在ASSM下默认只获取必要的chunk(default 1) (This is worse in ASSM than MSSM because ASSM only gets the amount of space requested while MSSM gets 128 chunks at a time.)。[Read More]
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author's avatar The Maclean Liu
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