在Oracle 12c 如果發現產出大量的trc files別慌, 想必是因為12c 資料庫會產出關於SQL Cursor 的trc file,
並在cursor 變為invalid 的時候寫到作業系統中, 相關參數為_kks_obsolete_dump_threshold (default 為1)
只要把他設定為0 即可以關閉並去掉不必要的IO 寫入. 或是apply Patch 22075064
ref1:
Huge Trace Files Created Containing "----- Cursor Obsoletion Dump sql_id=%s -----" (Doc ID 1955319.1)
When the value is equal to 0, the obsolete cursor dump will be disabled completely:
alter system set "_kks_obsolete_dump_threshold" = 0;
ref2:
http://www.peasland.net/2015/10/28/cursor-obsoletion-dump/
https://mikedietrichde.com/2015/10/20/where-do-these-large-trace-files-come-from-in-oracle-12c/
It appears this is a known bug in 12.1.0.2. Oracle turned on some diagnostic info and forgot to turn it off. But you can turn it off in your environments with the following:
alter system set "_kks_obsolete_dump_threshold" = 0;
ref3: http://pat98.tistory.com/896
12.2.0.1 Hidden Parameter _kks_obsolete_dump_threshold
在12.2 資料庫也有中此BUG
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