摘要：
The ASH report shows tables and data files with wait event 'utl_file I/O': CHANGES No changes. CAUSE ASH reports retrieve data from the dba_hist_activ 阅读全文
摘要：
sample 1: [sql] view plain copy select /*+INDEX(t IDX_SEL_ADD_DATE)*/ t.own_sys, count(1) from std_entp_login t where t.add_date > to_date('2010-12-28 阅读全文