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v$waitstat

原创 Linux操作系统 作者:yanggq 时间:2019-03-11 17:18:05 0 删除 编辑
CLASS COUNT TIME
data block 3096911 122276
sort block 0 0
save undo block 0 0
segment header 21 7
save undo header 0 0
free list 0 0
extent map 0 0
bitmap block 0 0
bitmap index block 0 0
unused 0 0
system undo header 0 0
system undo block 0 0
undo header 1190 1913
undo block 1521 2182

Eliminate HOT blocks from the application. Check for repeatedly scanned / unselective indexes.

Change PCTFREE and/or PCTUSED.

Check for 'right-hand-indexes' (indexes that get inserted into at the same point by many processes).

Increase INITRANS.

Reduce the number of rows per block.

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Contention with SEGMENT HEADER usually occur when full table scans are happening with data loads

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The time column is 1/100ths of a second

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Waits in "data block" indicate that we are trying to get concurrent access to datablocks for insert or update purposes. The solution is to increase the number of free lists for the affected segments.

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According to v$event_name, the p1 and p2 values for event
'buffer busy waits' are the file# and block# respectively,
but you have to be lucky with v$session_wait to see them,
or pay the massive overhead of setting event 10046 at level 8.

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/26706/viewspace-64571/,如需转载,请注明出处,否则将追究法律责任。

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