Tuesday, June 14, 2011

Low End of Fetch Count Wait

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The query activator doesn't fully read the query result set.
Consider speeding up the first set of rows fetch time. This is usually done by using the "FIRST_ROWS" hint.
Verify that the application is not performing a huge data scan for no reason. Unnecessarily large scans are expensive (in terms of CPU and I/O time).
The end of fetch count is identified by the number of times the specified cursor was fully executed since the cursor was brought into the library cache. Its value is not incremented when the cursor is partially executed, either because it failed during execution or because only the first few rows produced by this cursor were fetched before the cursor was closed or re-executed.
Low end of fetch count

Description
What to do next
n   Examine the statement's execution plan and make sure that unnecessary scans are not being performed.
n   Observe which program is calling the statement in the Activity Workspace, and check your Application to verify that there is a true need to scan all data and fetch only part of it.
Advice
n   Consider tuning the statement so that it scans fewer rows, by adding a "FIRST_ROWS" hint. Compare the result execution plan to the original, and run both statements to evaluate the influence of the change.
n   Consider changing the application’s logic to improve filtering. This will lead to smaller scans.


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