Active Session History (ASH) performed an emergency flush

最新推荐文章于 2025-07-26 10:47:10 发布

转载最新推荐文章于 2025-07-26 10:47:10 发布 · 124 阅读

本文讨论了ActiveSessionHistory (ASH)出现紧急刷新的问题，并建议通过增加_ASH_SIZE的值来解决这一问题。当前ASH大小为4194304字节，并已发生一次紧急刷新。可以通过查询v$ash_info来监控ASH大小及紧急刷新次数。

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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.