从下面的例子中可以看到，在生产数据库中对象的重新编译会导致library cache lock，所以应该尽量避免在业务高峰期编译对象。如果 从下面的例子中可以看到，在生产数据库中对象的重新编译会导致library cache lock，所以应该尽量避免在业务高峰期编译对象。如果是package或过程中存在复杂的依赖关系就极易导致library cache lock的出现，所以在应用开发的过程中，，也应该注意这方面的问题。 session1: SQL> select * from v$versio...
NAME AVALUE SDESC _inmemory_check_prot_meta FALSE If true, marks SMU area read only to prevent stray writes _inmemory_private_journal_quota 100 quota for transaction in-memory private journals _inmemory_private_journal_sharedpool_quota 20NAME AVALUE SDESC_inmemory_check_prot_meta FALSE If true, marks SMU area read only to prevent stray writes_inmemory_private_journal_quota 100 quota for transactio...
今天遇到一个生产库产生大量row cache lock,以下是相应步骤： 1 查询当时P1的情况 select INSTANCE_NUMBER,p1,count(*) cnt from dba_hist_active_sess_history where event=row cache lock and SAMPLE_TIME>=to_date(2018-08-31 10:00:00,yyyy-mm-dd hh24:mi:ss) and SAMPLE_TIME <=to_date(2018-08-31 10:40:00,yyyy-mm-dd hh24:mi:ss) group by INSTANCE_NUMBER,p1 order by cnt; 2 根据第一步查询的P1，代入到下面cache#...
1.Does undo buffer exists or changes will directly write to undo datafiles?Undo blocks are database blocks, so they will sit in the buffer cache like others, eg虽然无法控制undo buffer大小，但是可以查询到其大小，如下 SQL> select count(*)2 from v$bh3 where file# in (4 select file#5 from v$datafile6 where name like %UNDO% );COUNT(*) ----------54732.Does redo contains both undo & redo re...