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select buffer_gets, sql_text
from v$sqlarea
where buffer_gets > 200000
order by buffer_gets desc;
SQL语句的优化:
逻辑上
物理上
The driving table should be small
The other tables is indexed.
For large data sets (Sort_Area_Size)
The row sources are sorted already.
A sort operation does not have to be done.
For large data sets(Hash_Area_Size)
Optimizer_mode=CBO
Pga_aggregate_target is big enough
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原文地址：http://www.cnblogs.com/gary-bao/p/4314962.html
