High Cell Single Block Physical Read Causes Query Performance Downgrade on XT
(Doc ID 2753761.1)
Last updated on FEBRUARY 24, 2021
Applies to:Oracle Exadata Storage Server Software - Version 188.8.131.52.0 to 184.108.40.206.0 [Release 12.2 to 20.0]
Information in this document applies to any platform.
The select query has performance issue, the main wait is due to 'cell single block physical read'fromthe awr reports. Seems like the smart scan does not work properly.
The query is compared between XT and HC. The two dbs have every parameter, work load the same. I see the same plan with different amount of rows on both dbs. Flash is not included on XT. The same query on XT takes 47 sec to finish and it takes 9 sec on HC.
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