Monthly Archives: October 2012

Excessive transaction tables consistent reads – undo records applied in 11.2.0.3 – Part II

To reproduce the problem, flashback query was used. Normal case: select /*+full(a)*/ count(1) from iftp_dw.ar as of timestamp to_date(‘2012.10.05 01:00’, ‘yyyy.mm.dd hh24:mi:ss’) a; COUNT(1) ———- 2014667 Elapsed: 00:00:10.54 Execution Plan ———————————————————- Plan hash value: 1818353562 ——————————————————————- | Id | Operation … Continue reading

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Excessive transaction tables consistent reads – undo records applied in 11.2.0.3

The problem: select from table (full scan) runs for hours on 400MB table generating lot of (physical) IO on UNDO. The table has 250MB of indexes (counting 3.) Every time the excessive UNDO IO is generated the process A “select … Continue reading

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