Queries Generating High "Cell Single Block Physical Read" Wait Messages
(Doc ID 2119510.1)
Last updated on OCTOBER 06, 2022
Applies to:Oracle Database Backup Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 22.214.171.124 and later
Oracle Database Cloud Schema Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
Symptoms of this issue will appear as follows:
- Trace file entries that look similar to the following:
- The "Top 10 Foreground Events by Total Wait Time" section of the AWR report shows an exceedingly high number of waits but few to no average wait time. For example:
|Event||Waits||Total Wait Time (sec)||Wait Avg(ms)||% DB time||Wait Class|
|cell single block physical read||19,654,319||4847,1||0||9.7||User I/O|
- All or most of the events in the "Top SQL with Top Events" section of the ASH report are INDEX - STORAGE FAST FULL SCAN.
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