Month: July 2018

Oracle 18.3 hidden undocumented parameter list

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here is all of the Oracle 18c 18.3 on-premises hidden undocumented parameters: SQL> select n.ksppinm p_name, c.ksppstvl p_value 2 from sys.x$ksppi n, sys.x$ksppcv c 3 where n.indx=c.indx 4 and lower(n.ksppinm) like lower(‘\_%’) escape ‘\’; P_NAME P_VALUE ————————————————– ————————————————– _appqos_qt 10 _appqos_po_multiplier 1000 _appqos_cdb_setting 0 _ior_serialize_fault 0 _shutdown_completion_timeout_mins 60 _inject_startup_fault 0 _wait_outlier_detection_enable OFF _wait_outlier_event_names _wait_outlier_lambda_x1000 1500 … Read more

Troubleshoot DDL递归SQL触发的row cache lock deadlock(死锁)

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两个同时启动的JOB， truncate 了不同的对象DDL， 递归触发了DDL trigger的审计操作，在insert DDL日志表时，遇到了回收站空间再利用，再次递归触发了drop table BIN$ purge, 又属于DDL操作, 并且申请的回收站对象的row cache enqueue时，在2个跨实例会话互相等待对方持有对象lock造成死锁