Active Session History (ASH) performed an emergency flush. This may mean that ASH is undersized. If emergency flushes are a recurring issue, you may consider increasing ASH size by setting the value of _ASH_SIZE to a sufficiently large value. Currently, ASH size is 4194304 bytes. Both ASH size and the total number of emergency flushes since instance startup can be monitored by running the following query:
SQL> select total_size,awr_flush_emergency_count from v$ash_info;
TOTAL_SIZE AWR_FLUSH_EMERGENCY_COUNT
---------- -------------------------
4194304 1
SQL> select * from v$ash_info;
TOTAL_SIZE FIXED_SIZE SAMPLING_INTERVAL OLDEST_SAMPLE_ID OLDEST_SAMPLE_TIME LATEST_SAMPLE_ID
---------- ---------- ----------------- ---------------- --------------------------------------------------------------------------- ----------------
LATEST_SAMPLE_TIME SAMPLE_COUNT SAMPLED_BYTES SAMPLER_ELAPSED_TIME DISK_FILTER_RATIO
--------------------------------------------------------------------------- ------------ ------------- -------------------- -----------------
AWR_FLUSH_BYTES AWR_FLUSH_ELAPSED_TIME AWR_FLUSH_COUNT AWR_FLUSH_EMERGENCY_COUNT
--------------- ---------------------- --------------- -------------------------
4194304 4194304 1000 1168516 18-JUN-11 05.06.33.163000000 AM 1490473
21-JUN-11 10.40.34.688000000 PM 9257 3104088 2883663 10
2764680 557774 1 1
This issue can be ignored.
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1276779
