Table Prefetching Causes Intermittent Wrong Results in 9iR2,10gR1 and 10gR2 (Doc ID 406966.1)

Last updated on JULY 13, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 9.2.0.1 to 10.2.0.4 [Release 9.2 to 10.2]
Information in this document applies to any platform.
Confirmed in 9.2.0.7 , 10.2.0.1, 10.2.0.2, 10.2.0.3 and 10.2.0.4
Applies to 9.2.X, 10.1.X, 10.2.0.1, 10.2.0.2, 10.2.0.3, 10.2.0.4


Symptoms

The "table prefetch" has a dynamic component that can kick in or out depending on the load on the buffer cache making it unpredictable. So selects and DMLs can produce different results depending on the load on the server. This includes selects used in INSERTS, CTAS and MVIEWs. It is possible to get intermittent wrong results from a query which has the same execution plan for each execution due to a problem with the "table prefetch" feature (enabled by default from 9i onwards). The following symptoms can be seen:

Cause

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