索引是一般索引还是分区索引，可以看dba_indexes的partitioned字段。

如果partitioned字段是YES，说明是分区索引，那么，这个索引是global还是local，可以看dba_part_indexes的LOCALITY字段。

另外，我们还可以看ALIGNMENT字段，看这个索引是基于前导列（prefixed）还是非前导列。(注：global肯定是基于前导列，因为不能建基于非前导列的global索引。而local索引可以基于前导列和非前导列)

SQL> drop table invoices;

Table dropped.

--创建分区表，是range分区：
SQL> CREATE TABLE invoices
  2  (invoice_no    NUMBER NOT NULL,
  3   invoice_date  DATE   NOT NULL,
  4   invoice_area varchar2(200),
  5   invoice_serial number,
  6   comments      VARCHAR2(500),
  7   invoice_name varchar2(20)
  8   )
  9  PARTITION BY RANGE (invoice_date)
 10  (PARTITION invoices_q1 VALUES LESS THAN (TO_DATE('01/04/2001', 'DD/MM/YYYY')) TABLESPACE users,
 11   PARTITION invoices_q2 VALUES LESS THAN (TO_DATE('01/07/2001', 'DD/MM/YYYY')) TABLESPACE users,
 12   PARTITION invoices_q3 VALUES LESS THAN (TO_DATE('01/09/2001', 'DD/MM/YYYY')) TABLESPACE users,
 13   PARTITION invoices_q4 VALUES LESS THAN (TO_DATE('01/01/2002', 'DD/MM/YYYY')) TABLESPACE users);

Table created.

SQL>
SQL> --创建global分区索引，分区类型可以和表一样，也可以不一样。这个索引是和表分区类型一样，但是value less值不一样。
SQL> CREATE INDEX idx_glob_inv_ser ON invoices (invoice_serial,comments) GLOBAL
  2  PARTITION BY range (invoice_serial)
  3  (PARTITION invoices_q1 VALUES LESS THAN (10) TABLESPACE users,
  4   PARTITION invoices_q2 VALUES LESS THAN (20) TABLESPACE users,
  5   PARTITION invoices_q3 VALUES LESS THAN (30) TABLESPACE users,
  6   PARTITION invoices_q4 VALUES LESS THAN (40) TABLESPACE users,
  7   PARTITION invoices_qmax VALUES LESS THAN (MAXVALUE) TABLESPACE users);

Index created.

SQL>
SQL> --注意global分区索引，必须使用前导列，及如果索引列是 (comments,invoice_serial)，
SQL> --但partition by xx(invoice_serial)用了非前导列，是会报错，不能创建成功的。
SQL> CREATE INDEX idx_glob_inv_date ON invoices (comments,invoice_serial) GLOBAL
  2  PARTITION BY hash (invoice_serial) partitions 16;
PARTITION BY hash (invoice_serial) partitions 16
                                 *
ERROR at line 2:
ORA-14038: GLOBAL partitioned index must be prefixed


SQL>
SQL>
SQL> --创建另一个global分区索引，这个索引的分区类型是和表分区类型不一样的。用了hash分区。但是prefix前导列的原理也是一样的，需要使用前导列。
SQL> CREATE INDEX idx_glob_inv_date ON invoices (comments,invoice_serial) GLOBAL
  2  PARTITION BY hash (comments) partitions 16;

Index created.

SQL>
SQL>
SQL> --创建local索引，注意不能指定partition by的类型的，local索引的分区类型和分区数量必须和table一致，但是可以指定不同的表空间。这个local使用了前导列。
SQL> CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users);

Index created.
SQL>
SQL> --如果分区数量必须和table不一致，会报错：
SQL> CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users,
  6    PARTITION invoices_q5 TABLESPACE users);
CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
                               *
ERROR at line 1:
ORA-14024: number of partitions of LOCAL index must equal that of the underlying table

SQL> --创建local索引，注，local索引可以使用非前导列。而global索引只能使用前导列，不能使用非前导列。
SQL> CREATE INDEX idx_glo_inv_serl ON invoices (invoice_serial,invoice_date) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users);

Index created.
SQL>
SQL> --如果分区数量必须和table不一致，会报错：
SQL> CREATE INDEX idx_glo_inv_serl ON invoices (invoice_serial,invoice_date) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users
  6    PARTITION invoices_q5 TABLESPACE users,
  7    PARTITION invoices_q6 TABLESPACE users);
  PARTITION invoices_q5 TABLESPACE users,
  *
ERROR at line 6:
ORA-14010: this physical attribute may not be specified for an index partition


SQL>
SQL> --创建一般索引（即非分区索引）：
SQL> create index idx_glo_inv_comm on invoices (comments);

Index created.

SQL>
SQL>
SQL>
SQL>
SQL> select index_name,PARTITIONED from dba_indexes where table_name='INVOICES';

INDEX_NAME           PARTIT
-------------------- ------
IDX_GLOB_INV_SER     YES
IDX_GLOB_INV_DATE    YES
IDX_GLO_INV_DT       YES
IDX_GLO_INV_SERL     YES
IDX_GLO_INV_COMM     NO

SQL>
SQL> select INDEX_NAME,PARTITIONING_TYPE,LOCALITY,ALIGNMENT from dba_part_indexes where table_name='INVOICES';

INDEX_NAME           PARTITIONING_TYPE  LOCALITY     ALIGNMENT
-------------------- ------------------ ------------ ------------------------
IDX_GLOB_INV_SER     RANGE              GLOBAL       PREFIXED
IDX_GLOB_INV_DATE    HASH               GLOBAL       PREFIXED
IDX_GLO_INV_DT       RANGE              LOCAL        PREFIXED
IDX_GLO_INV_SERL     RANGE              LOCAL        NON_PREFIXED

SQL>

11g之前：

select spid, program from v$process
where program!= 'PSEUDO'
and addr not in (select paddr from v$session)
and addr not in (select paddr from v$bgprocess )
and addr not in (select paddr from v$shared_server);

11g之后：

select * from v$process where addr=(select creator_addr from v$session where sid=140);

参考：
How To Find The Process Identifier (pid, spid) After The Corresponding Session Is Killed? (Doc ID 387077.1)

在oracle数据库hang的情况下，我们可以用sqlplus -prelim / as sysdba登录数据库，进行一些收集信息的操作，也可以进行shutdown database的操作。这里需要注意几点：

1. process满是可以用sqlplus -prelim / as sysdba登录的

2. 从11.2.0.2开始，sqlplus -prelim / as sysdba是不能收集hanganalyze的信息，即使hanganalyze命令运行成功，但是在trace文件中看不到对应的信息，只能看到如下的报错：

ERROR: Can not perform hang analysis dump without a process state object and a session state object.
( process=(nil), sess=(nil) )

3. sqlplus -prelim / as sysdba可以收集process state dump，system state dump，dump errorstack，short_stack的操作。

参考：How to Collect Diagnostics for Database Hanging Issues (Doc ID 452358.1)

有一个库自从上线之后，主库的alertlog中一直有如下报错：

Tue Dec 20 14:42:16 2016
Error 12154 received logging on to the standby
PING[ARC2]: Heartbeat failed to connect to standby 'rmydb'. Error is 12154.

1. 检查远端的standby库已经启动，且已经到了mount以上的状态（即在read only的模式下Real Time Apply）。

2. 检查主库到远端的tnsping，正常。

3. 检查主库sqlplus user/pwd@tns 也是正常连接。

4. defer log_archive_dest_state_2后再enable，让archive进程意识到tnsnames.ora的变动。（怕之前修改过，archive进程没有意识到。），还是没用。依旧报错。

5. 再检查了一下，发现TNS_ADMIN的环境变量没有设置。所以用于心跳检测的archive进程，会找不到tns的配置文件。

临时解决办法：

不使用tnsnames.ora的配置文件，直接在log_archive_dest_2中设置：
alter system set log_archive_dest_2='SERVICE="(description=(address_list=(address=(protocol=TCP)(host=rhost)(port=1534)))(connect_data=(sid=mydb)))" LGWR ASYNC NOAFFIRM reopen=60 valid_for=(online_logfile,primary_role) db_unique_name=rmydb';

alter system set log_archive_dest_state_2=defer;

alter system set log_archive_dest_state_2=enable;

修改环境变量，添加TNS_ADMIN，待下次重启数据库生效。

参考：
Error 12154 received logging on to the standby whenever primary instance startup with srvctl (Doc ID 1943178.1)
RFS Is not coming up on standby Due to ORA-12154 on transport (primary side) (Doc ID 2196182.1)
Troubleshooting – Heartbeat failed to connect to standby (Doc ID 1432367.1)

我申请的vultr主机是单核CPU，15GB的ssd的硬盘，768M内存，每月1TB的流量，对于ss来说已经完成足够，目前有日本，新加坡，美国，德国，荷兰，法国等地的服务器。价格是每月5刀（每小时0.007刀），首次注册，如果用我这个Summer Promo Code，你可以额为获得20刀的费用；或者这个Linking Code，获得10刀的费用。前者的优惠幅度比较大，送你20刀，但是可能过了夏天就没有了，后者送10刀的优惠长期存在。目前已经运行了几个月，运行的非常稳定。除了php-fpm比较吃内存（单个进程40m~50M，有10个进程），其他都还好。

因此写了脚本当free小于50M的时候，自动重启php-fpm进程，当mysqld进程数小于2的时候，重启主机。两个多月下来，没有重启过主机，mysqld只是重启了3次。

另外由于将博客走了https，申请了letsencrypt的证书，每个月用脚本更新一次。更新的时候，先停nginx和php-fpm（其实只要停nginx就可以了。但是由于php-fpm比较吃内存，导致更新证书的时候，有时候需要更新Python packages，而在installing Python packages会因为内存不足而失败。所以我就干脆停了二者）,然后调用certbot-auto renew –quiet 自动进行证书更新。

####################[2016-12-10 02:10:01] OPERATION START ##################################
#
#
Free Memory before stop nginx&php-fpm: 64 MB
Stopping nginx: [  OK  ]
Stopping php-fpm: [  OK  ]
Free Memory after stop nginx&php-fpm: 233 MB
/root/.local/share/letsencrypt/lib/python2.6/site-packages/cryptography/__init__.py:26: DeprecationWarning: Python 2.6 is no longer supported by the Python core team, please upgrade your Python. A future version of cryptography will drop support for Python 2.6
  DeprecationWarning
Starting php-fpm: [  OK  ]
Starting nginx: [  OK  ]
Free Memory after restart nginx&php-fpm: 180 MB
#
#
####################[2016-12-10 02:10:15] OPERATION END ##################################

（1）一个月的osw记录：

（2）vultr官方的后台性能数据：

（3）loader.io网站进行了并发压力测试：
如果响应时间是2秒为可接受时间，那么大概可以承受500个左右的并发。

Unix/Linux中oracle数据库进程采用多进程模式，如我们可以在系统进程列表中看到pmon，smon，dbwr，lgwr，ckpt等oracle系统进程。随着oracle数据库功能增多，进程数量也随之增加，创建进程的开销以及进程上下文切换的开销也越来越大（进程状态切换 switching 是要直接硬件CPU资源），多线程结构中，线程切换在用户空间通过库函数实现，开销不在一个量级。所以，在oracle 12c中，有一个关于多线程的参数：threaded_execution，默认为false。启用的话，将其设置为true。启用之后，有如下变化：

1.进程数变少：
之前：

[oracle@ol6-121-rac2 diag]$ ps -ef |grep ora_
oracle    7562     1  0 14:54 ?        00:00:00 ora_pmon_cdbrac_1
oracle    7564     1  0 14:54 ?        00:00:00 ora_psp0_cdbrac_1
oracle    7567     1  4 14:54 ?        00:00:20 ora_vktm_cdbrac_1
oracle    7571     1  0 14:54 ?        00:00:00 ora_gen0_cdbrac_1
oracle    7573     1  0 14:54 ?        00:00:00 ora_mman_cdbrac_1
oracle    7577     1  0 14:54 ?        00:00:00 ora_diag_cdbrac_1
oracle    7579     1  0 14:54 ?        00:00:00 ora_dbrm_cdbrac_1
oracle    7581     1  0 14:54 ?        00:00:00 ora_ping_cdbrac_1
oracle    7583     1  0 14:54 ?        00:00:00 ora_acms_cdbrac_1
oracle    7585     1  0 14:54 ?        00:00:01 ora_dia0_cdbrac_1
oracle    7587     1  0 14:54 ?        00:00:00 ora_lmon_cdbrac_1
oracle    7589     1  0 14:54 ?        00:00:04 ora_lmd0_cdbrac_1
oracle    7591     1  0 14:54 ?        00:00:03 ora_lms0_cdbrac_1
oracle    7595     1  0 14:54 ?        00:00:00 ora_rms0_cdbrac_1
oracle    7597     1  0 14:54 ?        00:00:00 ora_lmhb_cdbrac_1
oracle    7599     1  0 14:54 ?        00:00:02 ora_lck1_cdbrac_1
oracle    7601     1  0 14:54 ?        00:00:00 ora_dbw0_cdbrac_1
oracle    7603     1  0 14:54 ?        00:00:00 ora_lgwr_cdbrac_1
oracle    7605     1  0 14:54 ?        00:00:00 ora_ckpt_cdbrac_1
oracle    7607     1  0 14:54 ?        00:00:00 ora_smon_cdbrac_1
oracle    7609     1  0 14:54 ?        00:00:00 ora_reco_cdbrac_1
oracle    7611     1  0 14:54 ?        00:00:00 ora_lreg_cdbrac_1
oracle    7613     1  0 14:54 ?        00:00:00 ora_rbal_cdbrac_1
oracle    7615     1  0 14:54 ?        00:00:00 ora_asmb_cdbrac_1
oracle    7617     1  0 14:54 ?        00:00:01 ora_mmon_cdbrac_1
oracle    7621     1  0 14:54 ?        00:00:00 ora_gcr0_cdbrac_1
oracle    7623     1  0 14:54 ?        00:00:00 ora_mmnl_cdbrac_1
oracle    7625     1  0 14:54 ?        00:00:00 ora_d000_cdbrac_1
oracle    7627     1  0 14:54 ?        00:00:00 ora_s000_cdbrac_1
oracle    7629     1  0 14:54 ?        00:00:00 ora_lck0_cdbrac_1
oracle    7634     1  0 14:54 ?        00:00:00 ora_rsmn_cdbrac_1
oracle    7644     1  0 14:54 ?        00:00:00 ora_ppa7_cdbrac_1
oracle    7668     1  0 14:54 ?        00:00:00 ora_mark_cdbrac_1
oracle    8033     1  0 14:55 ?        00:00:00 ora_o000_cdbrac_1
oracle    8038     1  0 14:56 ?        00:00:00 ora_tmon_cdbrac_1
oracle    8040     1  0 14:56 ?        00:00:00 ora_tt00_cdbrac_1
oracle    8042     1  0 14:56 ?        00:00:00 ora_gcr1_cdbrac_1
oracle    8044     1  0 14:56 ?        00:00:00 ora_smco_cdbrac_1
oracle    8046     1  0 14:56 ?        00:00:00 ora_w000_cdbrac_1
oracle    8049     1  0 14:56 ?        00:00:00 ora_gtx0_cdbrac_1
oracle    8054     1  0 14:56 ?        00:00:00 ora_rcbg_cdbrac_1
oracle    8101     1  0 14:56 ?        00:00:00 ora_aqpc_cdbrac_1
oracle    8126     1  3 14:56 ?        00:00:11 ora_p000_cdbrac_1
oracle    8188     1  0 14:56 ?        00:00:00 ora_o001_cdbrac_1
oracle    8247     1  1 14:56 ?        00:00:04 ora_p001_cdbrac_1
oracle    8249     1  0 14:56 ?        00:00:00 ora_p002_cdbrac_1
oracle    8251     1  0 14:56 ?        00:00:00 ora_p003_cdbrac_1
oracle    8302     1  0 14:56 ?        00:00:00 ora_qm02_cdbrac_1
oracle    8304     1  0 14:56 ?        00:00:00 ora_qm05_cdbrac_1
oracle    8306     1  0 14:56 ?        00:00:00 ora_q002_cdbrac_1
oracle    8310     1  0 14:56 ?        00:00:00 ora_q004_cdbrac_1
oracle    8327     1  0 14:56 ?        00:00:00 ora_ppa6_cdbrac_1
oracle    8663     1  1 14:56 ?        00:00:02 ora_cjq0_cdbrac_1
oracle    8708     1  0 14:56 ?        00:00:00 ora_p004_cdbrac_1
oracle    8710     1  0 14:56 ?        00:00:00 ora_p005_cdbrac_1
oracle    9052     1  0 14:58 ?        00:00:00 ora_q003_cdbrac_1
oracle    9118     1  0 14:59 ?        00:00:00 ora_p006_cdbrac_1
oracle    9120     1  0 14:59 ?        00:00:00 ora_p007_cdbrac_1
oracle    9294  7647  0 15:01 pts/0    00:00:00 grep ora_
[oracle@ol6-121-rac2 diag]$

之后：

[oracle@ol6-121-rac1 admin]$ ps -ef |grep ora_
oracle   10514     1  0 14:59 ?        00:00:00 ora_pmon_cdbrac_1
oracle   10516     1  0 14:59 ?        00:00:00 ora_psp0_cdbrac_1
oracle   10548     1  3 14:59 ?        00:00:13 ora_vktm_cdbrac_1
oracle   10552     1  2 14:59 ?        00:00:07 ora_u004_cdbrac_1
oracle   10558     1  7 14:59 ?        00:00:28 ora_u005_cdbrac_1
oracle   10563     1  0 14:59 ?        00:00:00 ora_ping_cdbrac_1
oracle   10569     1  0 14:59 ?        00:00:02 ora_u010_cdbrac_1
oracle   10578     1  0 14:59 ?        00:00:00 ora_dbw0_cdbrac_1
oracle   11244  9828  0 15:05 pts/0    00:00:00 grep ora_
[oracle@ol6-121-rac1 admin]$

2. 必须网络登录，不能本地验证：

[oracle@ol6-121-rac1 admin]$ sqlplus "sys/oracle@CDBRAC as sysdba"

SQL*Plus: Release 12.1.0.1.0 Production on Wed Dec 9 15:04:33 2015

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options

SQL>
SQL>

3. 可以不同实例不同值：

SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
cdbrac_1

SQL> show parameter thread

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
parallel_threads_per_cpu             integer     2
thread                               integer     0
threaded_execution                   boolean     TRUE
SQL>


SQL> select instance_name from v$instance;

INSTANCE_NAME
----------------
cdbrac_2

SQL> show parameter thread

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
parallel_threads_per_cpu             integer     2
thread                               integer     0
threaded_execution                   boolean     FALSE
SQL>

4. listener相关修改：
当threaded_execution这个字被设置成true后，在listener.ora文件中，需要加上：

DEDICATED_THROUGH_BROKER_[listener-name]=ON。

参考：
http://docs.oracle.com/database/121/REFRN/GUID-7A668A49-9FC5-4245-AD27-10D90E5AE8A8.htm#REFRN10335
http://docs.oracle.com/database/121/CNCPT/process.htm#CNCPT1245

2017年的第一天，因为闰秒的关系，加上时差的原因，我国将在北京时间2017年1月1日的7时59分59秒和全球同步进行闰秒调整，届时会出现7:59:60的特殊现象。(国家授时中心闰秒公告)

那么闰秒对数据库有什么影响？

（一）具体的说：
可以参考：Information Center: Leap Second Information for All Products – Database – Exadata – Middleware – Exalogic – Linux – Sun – Fusion – EBS – JDE – Siebel – Peoplesoft (Doc ID 2019397.2)

这是一篇非常详尽的关于Oracle所有产品，是否受闰秒影响的汇总文档。包括了Sun Microsystems，Linux & VM，Database & EM，Exadata & Exalogic，Fusion Middleware，Applications。

（二）简单的说：

1. 对于RAC系统，NTP闰秒问题可能会导致节点reboot。但以下两种情况将不受影响：
1.1 使用了第三方cluster 软件，如Sun Cluster or Veritas SFRAC 配置。
1.2 使用 Oracle Clusterware 10.2.0.4 及更高的版本(包括 11g、12c 等)。

2. 对于Linux 及Oracle VM，部分应用程序无法处理该非常规“23:59:60”的时间戳，可能会导致应用挂起或主机重启。

3. 对于单节点数据库运行无影响，系统层闰秒调整不会对RDBMS 产生影响。

解决方案：
对于10.2.0.4以下的版本的RAC，导致节点reboot的触发条件必须同时满足如下2个条件：
1. xntpd没有启用slewing
2. oracle的clusterware（10g还没有gi），没有打上fix for bug 5015469 or bug 6022204

因此，推荐的解决方案是避免上面的条件1，启用xntpd的slewing来解决问题：

a). 在linux中修改/etc/sysconfig/ntpd中，修改:
OPTIONS="-u ntp:ntp -p /var/run/ntpd.pid -x"，使用-x参数启动ntp。

b). 在solaris中修改/etc/inet/ntp.conf中，添加:
slewalways yes
disable pll

c). 其他平台，请参考厂家的系统管理手册

修改后重启ntpd服务。

参考：
Information Center: Leap Second Information for All Products – Database – Exadata – Middleware – Exalogic – Linux – Sun – Fusion – EBS – JDE – Siebel – Peoplesoft (Doc ID 2019397.2)
How Leap Second Affects The OS Clock on Linux and Oracle VM (Doc ID 1453523.1)
NTP leap second event causing Oracle Clusterware node reboot (Doc ID 759143.1)

Solaris系统将被停止开发，这个消息，据我所看到的，最初的来源是来自thelayoff网站的消息『Solaris being canned, at least 50% of teams to be RIF’d in short term』

All hands meetings being cancelled on orders from legal to prevent news from spreading.

Hardware teams being told to cease development.

There will be no Solaris 12, final release will be 11.4.

Orders coming straight from Larry.

No info on timing yet.

但是Oracle官方一直没有回应这个消息。

估计很多客户也在求证这个消息，上周，system团队的老大发了个邮件，希望澄清这个事情。

首先，开篇就说了solaris没有死。

然后说Solaris后续的功能更新将基于版本的后面的小数点，而不是大版本。———— 所以……谣言没错，确实没有了solaris 12，只有solaris 11.XX。

然后，说了solaris 11的Premier Support至少会持续到2031年。

最后，说了如果客户需要和硬件团队的领导邮件沟通上述情况，他们会很乐意。

客户一个测试环境，一个主机上面运行了很多数据库，某库的程序会时不时报错ora-4030。

加大了pga，然后还检查了ulimit的 data 和 stack都是ulimit。还是报错。

进而检查/var/adm/messages，发现有报错swap不足的情况。

所以，解决方法是加大物理内存，或者加大swap（文档要求是对于8G以上物理内存，swap的设置是0.7倍物理内存），

参考：『一个奇怪的ora-4030错误的诊断过程』（其实这个文档中的客户和我的客户，是同一个。：））

今天整理dropbox文件夹的时候，发现还保留着老东家IBM百年诞辰的时候，发的一本名为《让世界更美好：塑造一个世纪与一家公司的理念》的专刊。

百年老店自然有他存活百年的道理，当年这本书发给员工的时候，不知是基于成本控制的考虑，还是员工激励的考虑，并不是所有员工都能拿到纸质书。我只是“有幸”拿到了它的电子版。下面分别是中文版和英文版的两本书，分享给各位IBM的粉丝。

下载中文版：『2011_09_02_2301_让世界更美好_PDF』(File size:53MB)

下载英文版：『2011_06_12_3144_Centennial_book__eBook_format』(File size:31MB)

在11.2.0.2之后，有一个非常重要的dataguard的patch。在使用物理dataguard环境（包括ADG），进行switchover之后，存在导致index block上的invalid SCNs的坏块问题。

国内已经好几个行业的大客户，都遇到了这个问题。

在index block中的失效的ITL commit SCN，会违反scn依赖性检查，从而可能抛出如下报错：

ORA-1555
ORA-600 [2663]
ORA-600 [kdsgrp1]
ORA-600 [ktbdchk1: bad dscn]

注：此bug只是影响index block，不影响data block，所以不会造成数据丢失。可以通过重建索引修复。

但是如果你的索引很大，那么修复可能需要一段时间。

解决方法也历经多个补丁，一开始是Patch 8895202，后来是Patch 13513004，现在是Patch 22241601。

打了Patch 22241601这个补丁之后，不再需要手工设置_ktb_debug_flags=8，因为打完补丁自动设置了_ktb_debug_flags=8。在index block cleanout的时候，oracle会自动修复index block上的invalid SCNs的问题。同时，你可以在alertlog中看到相关修复的提示：

Healing Corrupt DLC ITL objd:%d objn:%d tsn:%d rdba:<rdba> itl:%d
 option:%d xid:<xid> cmtscn:<scn> curscn:<scn>

如果你目前的PSU只是打到11.2.0.4.8之后，11.2.0.4.161018之后，那么目前这个补丁只有linux X86和linux X86-64版本；如果你已经打PSU到11.2.0.4.161018了，那么目前基本全平台都有这个补丁。

对于没有补丁的平台，建议通过设置隐含参数_ktb_debug_flags=8来解决。

参考：
ALERT Bug 22241601 ORA-600 [kdsgrp1] / ORA-1555 / ORA-600 [ktbdchk1: bad dscn] / ORA-600 [2663] due to Invalid Commit SCN in INDEX (Doc ID 1608167.1)

Oracle开始支持在docker上oracle数据库了，注意，是单实例，RAC不支持。docker的操作系统需要时候Oracle linux 7或者RHEL 7。

Oracle will support customers running Oracle Database (single instance) in Docker containers. Oracle will only provide support when running the database in Docker containers running on Oracle Linux and Red Hat RHEL. Supported versions of these Linux distributions are

Oracle Linux 7
Red Hat Enterprise Linux 7 (RHEL)

Oracle does not support Oracle Database running in a Real Application Clusters (RAC) configuration in Docker containers.

另外，在github上也有一个非官方的如何制作oracle database on docker的image。

参考：
Oracle Support for Database Running on Docker (Doc ID 2216342.1)

不少朋友可能已经知道我离职了，是的，我已经不在ORACLE公司，我去了大疆（DJI）。

加入大疆是个非常巧合的机缘。

2016年9月27日，大疆在纽约发布了他们的新的无人机：御（Mavic Pro）。

如果你是第一批订购Mavic的用户，必然知道这是很长的一次购物体验，由于产能有限，第一批Mavic需要等待6～8周才能到货。在等待的过程中，我也follow了他们的微信公共帐号，没事上上论坛，阅读一下说明书，和飞友们一起交流一下经验。

在等待了一个半月之后，大疆的微信公共帐号发布了一则消息，11月19日是大疆的open day，可以参加他们的活动，介绍企业文化，吃吃小点心，和工程师聊天，同时也可以投简历加入大疆。而我一直还在等待Mavic的到货，于是怀着“顺便去问问Mavic什么时候能到货”的心态，我报名了这次活动，投了简历。我当时也在大疆的论坛发了这则消息，问问有没有同路人。

过去之后，没想到上午就开始了招聘活动，经过了4轮面试，一切都挺顺利，大疆与我都挺认可对方的。他们问我，为什么想换工作，我也说了大实话，我觉得大疆能做出这样令人赞叹的无人机，非常了不起，也希望能为做出这样了不起的产品的公司尽一份力。

另外，也非常感谢大疆的DBA对我的极力推荐，让我脱颖而出。

于是我从去“追货”变成了被“招安”。

而更加巧合的是，我在平安的另外一位好朋友，也去了大疆。一天中午，他得知我将要离职的消息，问我下一家公司是哪里，我说我先保密，后面再公布好了，他说可以说说是哪个行业吗，我想了想，说如果说了是哪个行业，基本你就能猜到是哪家公司了，他说是不是大疆？我吃了一惊，没想到他一猜就中了，他把我叫到一旁，对我露出了一个神秘的微笑，说他也将要去大疆，呵呵……

没想到我们没在平安成为同事，在大疆却成了同事。真是无巧不成书！好期待与他的再次合作。

人的一生可能就只会遇到几个转变的机会，错过了就没了。这次离开ORACLE，加入大疆，也是对我一次比较大的转变，因为我不再局限在ORACLE产品，会有更多开源技术的挑战；不再是单兵作战，而是和团队一起努力，完成目标；不再是作为乙方、作为顾问的指导角色，而是真正的owner，完全对自己的系统负责。

想到这些转变和挑战，我心中既有不安，也充满热情。感谢过去4年多以来，ORACLE对我的磨练和培养，也感谢平安特别是汪总对我的支持和肯定，您一直是我的榜样。下一站，DJI，我来了！

LAST UPDATE:

Dec 13, 2016

APPLIES TO:

Oracle Database - Enterprise Edition - Version 12.1.0.1 to 12.1.0.2 [Release 12.1]
Information in this document applies to any platform.

PURPOSE:

In recent quarters, during non-code closure bug review for Performance, it was found that more than 50% of duplicates (36,96) closed by Sustaining Engineering (SE) belonged to version 12.1. As a result this document was created to list most commonly reported and share this with Tier-1 engineers so that they could check this before logging any new bugs. Thus the Goal of this document is to provide a list of known bugs reported in 12C for database & SQL performance for support analysts to check before logging new bugs.

In addition to the bugs listed in this article, there is also a useful list of Documented Database Bugs With High "Solved SR" Count where a high number of Service Requests means that there are more than 50 "Solved SR" entries for the bug - ie: all bugs in this doc have > 50 "Solved SR" entries.” :

Document 2099231.1 Documented Database Bugs With High "Solved SR" Count

DETAILS:
Query Optimizer / SQL Execution

Bug 20271226 - QUERY INVOLVING VIRTUAL COLUMN AND PRIMARY KEY CONSTRAINT CRASHES
Document 19046459.8 - Inconsistent behavior of OJPPD
Document 22077191.8 - Create Table As Select of Insert Select Statement on 12.1 is Much Slower Than on 11.2
Bug 20597568 - PJE INCORRECTLY APPLIED TO A CONNECT BY QUERY
Document 18456944.8 - Suboptimal plan for query fetching ROWID from nested VIEW with fix 10129357
Bug 20355502 - QUERY PARSE NEVER ENDS ( BURNING CPU ALL THE TIME)
Document 20355502.8 Limit number of branches on non-cost based OR expansion
Document 20636003.8 - Slow Parsing caused by Dynamic Sampling (DS_SRV) queries in 12.1.0.2
Bug 22513913 - QUERY FAILS WITH ORA-07445: [KKOSJT()+281] WHEN USING DATABASE LINK
Bug 22020067 - UPGRADE 11.2.0.2 TO 11.2.0.4 SCALAR SUBQUERY UNNEST DISABLED
Bug 21099502 - JPPD Not Happening In UNION ALL View Having Group-by and Aggregates
Bug 22862828 - Regression with 22706363, JPPD Does Not Occur Despite the Fix Control 9380298 is ON
Bug 19295003 - High CPU While Parsing Huge SQL [kkqtutlTravOptAndReplaceOJNNCols]
Document 21091518.8 - Suboptimal plan for SQLs using UNION-ALL with bug fix 18304693 enabled
Document 22113854.8 - Query Against ALL_SYNONYMS Runs Slow in 12C
Document 21871902.8 - SELECT query fails with ORA-7445 [qerixRestoreFetchState2] - superseded by
Document 22255113.8 - High parse time with high memory and CPU usage
Document 22339954.8 - Bug 22339954 - High Parse Time for Query Using UNPIVOT Operator
Document 19490852.8 - Excessive "library cache lock" waits for DML with PARALLEL hint when parallel DML is disabled
Bug 20226806 - QUERY AGAINST ALL_CONSTRAINTS AND ALL_CONS_COLUMNS RUNS SLOWER IN 12.1.0.2
duplicate of Bug 20355502 - QUERY PARSE NEVER ENDS ( BURNING CPU ALL THE TIME)
Document 20118383.8 - Long query parse time in 12.1 when many histograms are involved - superseded by
Document 18795224.8 - Hard parse time increases with fix 12341619 enabled, fixed in 12.2
Document 19475484.8 - Cardinality of 0 for range predicate with fix for bug 6062266 present (default), fixed in 12.2
Document 2182951.1 Higher Elapsed Time after Updating from 11.2.0.4 to 12.1.0.2
Document 18498878.8 - medium size tables do not cached consistently causing unnecessary waits on direct path read, fixed in 12.2
Bug 23516956 - DYNAMIC SAMPLING QUERIES CONTAINS INCORRECT HINTS
duplicate of Document 19631234.8 - Suboptimal execution plan for Dynamic Sampling Queries
Bug 20503656 - Remote SQLs having group by with bind variables throw ORA-00979, fixed in 12.2
Bug 19047578 - Optimizer No Longer Uses Function Based Index When CURSOR_SHARING=FORCE
Document 22734628.8 - Wrong results from UNION ALL using OJPPD with cost based transformation disabled, fixed in 12.2
Bug 21839477 - ORA-7445 [QESDCF_DFB_RESET] WITH FIX FOR BUG:20118383 ON, fixed in 12.2
Document 20774515.8 - Wrong results with partial join evaluation, fixed in 12.2
Bug 21303294 - Wrong Result Due to Lost OR Predicate in Bitmap Plan, fixed in 12.2
Document 22951825.8 - Wrong Results with JPPD, Concatenation and Projection Pushdown, fixed in 12.2
Bug 19847091 - HUGE INLIST SQL HANGS DURING PARSE
superseded by Bug 20384335 - CPU REGRESSION DUE TO PLAN CHANGE IN ONE SELECT SQL WITH IN PREDICATE, fixed in 12.2

SQL Plan Management (SPM)

Document 20877664.8 - SQL Plan Management Slow with High Shared Pool Allocations
Document 21075138.8 - SPM does not reproduce plan with SORT UNIQUE, affected from 11.2.0.4 and fixed in 12.2 only
Document 20978266.8 - SPM: SQL not using plan in plan baselines and plans showing as not reproducible - superseded, fixed in 12.2
Document 19141838.8 - ORA-600 [qksanGetTextStr:1] from SQL Plan Management after Upgrade to 12.1
Document 18961555.8 - Static PL/SQL baseline reproduction broken by fix for bug 18020394, fixed in 12.2
Document 21463894.8 - Failure to reproduce plan with fix for bug 20978266, fixed in 12.2
Document 2039379.1 ORA-04024: Self-deadlock detected while trying to mutex pin cursor" on AUD_OBJECT_OPT$ With SQL Plan Management (SPM) Enabled

Wrong Results

Document 20214168.8 - Wrong Results using aggregations of CASE expression with fix of Bug 20003240 present
Bug 21971099 - 12C WRONG CARDINALITY FROM SQL ANALYTIC WINDOWS FUNCTIONS
Document 16191689.8 - Wrong resilts from projection pruning with XML and NESTED LOOPS
Bug 18302923 - WRONG ESTIMATE CARDINALITY IN HASH GROUP BY OR HASH JOIN
Bug 21220620 - WRONG RESULT ON 12C WHEN QUERYING PARTITIONED TABLE WITH DISTINCT CLAUSE
Document 22173980.8 - Wrong results (number of rows) from HASH join when "_rowsets_enabled" = true in 12c (default)
Bug 20871556 - WRONG RESULTS WITH OPTIMIZER_FEATURES_ENABLE SET TO 12.1.0.1 OR 12.1.0.2
Bug 21387771 - 12C WRONG RESULT WITH OR CONDITION EVEN AFTER PATCHING FOR BUG:20871556
Bug 22660003 - WRONG RESULTS WHEN UNNESTING SET SUBQUERY WITH CORRELATED SUBQUERY IN A BRANCH
Bug 22373397 - WRONG RESULTS DUE TO MISSING PREDICATE DURING BITMAP OR EXPANSION
Bug 22365117 - SQL QUERY COMBINING TABLE FUNCTION WITH JOIN YIELDS WRONG JOIN RESULTS
Bug 20176675 - Wrong results for SQLs using ROWNUM<=N when Scalar Subquery is Unnested (VW_SSQ_1)
Document 19072979.8 - Wrong results with HASH JOIN and parameter "_rowsets_enable"
Document 22338374.8 - ORA-7445 [kkoiqb] or ORA-979 or Wrong Results when using scalar sub-queries
Document 22365117.8 - Wrong Results / ORA-7445 from Query with Table Function
Bug 19318508 - WRONG RESULT IN 12.1 WITH NULL ACCEPTING SEMIJOIN - fixed in 12.2
Bug 21962459 - WRONG RESULTS WITH FIXED CHAR COLUMN AFTER 12C MIGRATION WITH PARTIAL JOIN EVAL
Bug 23019286 - CARDINALITY ESTIMATE WRONG WITH HISTOGRAM ON COLUMN GROUP ON CHAR/NCHAR TYPES, fixed in 12.2
Bug 23253821 - Wrong Results While Running Merge Statement in Parallel, fixed in 12.2
Document 18485835.8 - Wrong results from semi-join elimination if fix 18115594 enabled, fixed in 12.2
Document 18650065.8 - Wrong Results on Query with Subquery Using OR EXISTS or Null Accepting Semijoin, fixed in 12.2
Document 19567916.8 - Wrong results when GROUP BY uses nested queries in 12.1.0.2 - superseded by
Document 20508819.8 - Wrong results/dump/ora-932 from GROUP BY query when "_optimizer_aggr_groupby_elim"=true - superseded by
Document 21826068.8 - Wrong Results when _optimizer_aggr_groupby_elim=true
Document 20634449.8 - Wrong results from OUTER JOIN with a bind variable and a GROUP BY clause in 12.1.0.2
Bug 20162495 - WRONG RESULTS FROM NULL ACCEPTING SEMI-JOIN, fixed in 12.2.

Statistics

Bug 22081245 - COPY_TABLE_STATS DOES NOT WORK PROPERLY FOR TABLES WITH SUB PARTITIONS
Bug 22276972 - DBMS_STATS.COPY_TABLE_STATS INCORRECTLY ADJUST MIN/MAX FOR PARTITION COLUMNS
Document 19450139.8 Slow gather table stats with incremental stats enabled
Bug 21258096 - UNNECESSARY INCREMENTAL STATISTICS GATHERED FOR UNCHANGED PARTITIONS DUE TO HISTOGRAMS
Bug 23100700 - PERFORMANCE ISSUE WITH RECLAIM_SYNOPSIS_SPACE, fixed in 12.2
Document 21171382.8 - Enhancement: AUTO_STAT_EXTENSIONS preference on DBMS_STATS - Enhancement To turn off automatic creation of extended statistics in 12c
Document 21498770.8 - automatic incremental statistics job taking more time with fix 16851194, fixed in 12.2
Document 22984335.8 - Unnecessary Incremental Partition Gathers/Histogram Regathers

Errors

Document 20804063.8 ORA-1499 as REGEXP_REPLACE is allowed to be used in Function-based indexes (FBI)
Document 17609164.8 ORA-600 [kkqctmdcq: Query Block Could] from ANSI JOIN with no a join predicate
Document 21482099.8 ORA-7445 [opitca] or ORA-932 errors from aggregate GROUP BY elimination
Document 21756734.8 - ORA-600 [kkqcsnlopcbkint : 1] from cost based query transformation
Bug 22566555 - ORA-00600 [KKQCSCPOPNWITHMAP: 0] FOR SUBQUERY FACTORING QUERY WITH DISTINCT
Bug 21377051 - ORA-600 [QKAFFSINDEX1] FROM DELETE STATEMENT
Document 21188532.8 - Unexpected ORA-979 with fix for bug 20177858 - superseded by
Bug 23343584 - GATHER_TABLE_STATS FAILS WITH ORA-6502/ORA-6512
duplicate of Bug 22928015 - GATHER DATABASE STATS IS RUNNING VERY SLOWLY ON A RAC ENVIRONMENT
Document 21038926.8 - ORA-7445 [qesdcf_dfb_reset] with fix for bug 20118383 present, fixed in 12.2
Document 18405192.8 - ORA-7445 under qervwFetch() or qervwRestoreViewBufPtrs() when deleting from view with an INSTEAD OF trigger
Document 21968539.8 - ORA-600 [kkqcscpopnwithmap: 0]
Document 18201352.8 - ORA-7445 [qertbStart] or similar errors from query with DISTINCT and partial join evaluation (PJE) transformation
Document 19472320.8 - ORA-600 [kkqtSetOp.1] from join factorization on encrypted column
Bug 22394273 - ORA-600 [QESMMCVALSTAT4] FROM SELECT STATEMENT
Document 21529241.8 - DBMS_STATS ORA-6502: "PL/SQL: numeric or value error"
Document 20505851.8 - ORA-600 / ORA-7445 qksqbApplyToQbcLoc from WITH query that has duplicate predicates
Bug 19952510 - ORA 600 [QERSCALLOCATE: BUFFER SIZE LIMIT] AND ORA 600 [KEUUXS_1]
Bug 21274291 - ORA-600 :[17147] AND [ORA-600 :[KGHALF] DURING AN INSERT
Bug 21524270 - ORA-28115 ON ORACLE 12C WITH VPD IN MERGE STMT, BUT INSERT SUCCEEDS
Bug 20660917 - INSTEAD OF TRIGGER IS FIRED TWICE INSTEAD OF ONCE WITH FIX TO 13812807, Causes ORA-07445 [kxtifir] in 12.1.0.2 - fixed in 12.2.

Adaptive Query Optimization

Bug 18745156 - ADAPTIVE DYNAMIC SAMPLING CAUSES BAD CARDINALITY ESTIMATE
Bug 16033838 - TST&PERF: ADAPTIVE JOINS LEADS TO WORSE PLAN FOR QUERY B4TKVSMPFSP85
Document 20465582.8 High parse time in 12c for multi-table join SQL with SQL plan directives enabled - superseded
Document 20807398.8 ORA-600 [kgl-hash-collision] with fix to Bug 20465582 installed
Document 18430870.8 Adaptive Plan and Left Join Give Wrong Result
Bug 21912039 : GSIAS: PERF REGRESSION: ADAPTIVE PLAN SQL_ID DN50XQR69FJ0F GETS WORSE
  duplicate of Bug 20243268 : EM QUERY WITH SQL_ID 4RQ83FNXTF39U PERFORMS POORLY ON ORACLE 12C RELATIVE TO 11G
Bug 19731829 - ISSUES WITH PACK AND UNPACK OF SQL PLAN DIRECTIVES
Document 20370037.8 - KGLH0 growth leading to ORA-4031 by cardinality feedback, fixed in 12.2
Document 20413540.8 - Excessive executions of SQL frjd8zfy2jfdq

Library cache / Rowcache / Shared Cursors / Dictionary / Buffer cache

Document 19450314.8 Unnecessary invalidations in 12c
Bug 21153142 - ROW CACHE LOCK SELF DEADLOCK ACCESSING SEED PDB
Bug 22081947 - ORA-4023 MAY OCCUR IN ACTIVE DATA GUARD ENVIRONMENTS
Bug 12387079 - THE CHILD CURSOR IS INCREASED WHEN THE CURSOR IS KEPT AND EXECUTED DDL
  superseded by Bug 19239846 - FIX FOR Bug 12387079 NEEDS TO BE RE-WORKED
Bug 12320556 - HIGH VERSION COUNTS OCCUR DUE TO AUTH_CHECK_MISMATCH, INSUFF_PRIVS_REM=Y
  superseded by Bug 21515534 - QUERY USING 2 REMOTE DB NOT SHARED - AUTH_CHECK_MISMATCH ,INSUFF_PRIVS_REM
Document 21515534.8 Query referencing multiple remote databases not shared with reason AUTH_CHECK_MISMATCH INSUFF_PRIVS_REM
Document 20907061.8 High number of executions for recursive call on col$
Document 20476175.8 High VERSION_COUNT (in V$SQLAREA) for query with OPT_PARAM('_fix_control') hint
Bug 21799609 - ORA-04024 DEADLOCK ON STARTUP ON SYS.ECOL$ ON LOAD HISTOGRAMS
  duplicate of Bug 19469538 - LOADING OF DATA IN ECOL$ TABLE IS NON-OPTIMAL FOR QUERIES
Bug 22586498 - HUGE M000 TRACEFILE DUE TO OBSOLETE CURSOR DUMPS
Document 20906941.8 - DBW0 spins with high CPU
Bug 17700290 - TST&PERF: LIBRARY CACHE MUTEX WAIT TIME INCREASED HUGELY IN MAIN - affected 12.1.0.2, fixed in 12.2 only
Bug 22733141 - GATHERING STATS ON X$KQLFBC HANGS
Bug 23098370 - DBWR CAN ISSUE MORE THAN SSTMXIOB IO'S
Bug 23103188 - Incorrect ORA-1031 or ORA-942 during Grant due to 22677790, fixed in 12.2
Bug 19340498 - CDB:NO ROWS RETURNED WHEN QUERYING V$SQL_SHARED_MEMORY INSIDE A PDB
Bug 23514710 - CROSS-CONTAINER FIXED TABLE NOT OBSOLETED WHEN PARENT IS MARKED OBSOLETE in ADG Env
Document 19392364.8 - Process spin in kkscsFindMatchingRange() with adaptive cursor sharing, fixed in 12.2
Document 2096561.1 - High Amount Of Shared Memory Allocated Into KGLH0 Heap In 12.1.0.2
Document 2119923.1 - Shared Pool from KGLH0 constantly growing causing ORA-04031 and Latch contention
Document 23168642.8 - Sporadic ORA-600 [kglunpin-bad-pin] / ORA-14403 / high 'library cache: mutex x' using partitions and deferred seg creation / ORA-600 [qesmascTrimLRU_1] with fix 21759047, fixed in 12.2
Document 21759047.8 - High 'library cache: mutex x' Contention when Many Sessions are Executing Cursors Concurrently Against a Partitioned Table - superseded, fixed in 12.2
Document 14380605.8 - High "library cache lock", "cursor: pin S wait on X" and "library cache: mutex X" waits, fixed in 12.2
Document 19822816.8 - High parse time for SQL with PIVOT and binds (can block LGWR on "library cache lock"), fixed in 12.2
Document 13542050.8 - 'library cache: mutex X' waits : A mutex related hang with holder around 65534 (0xfffe), fixed in 12.2
Document 21834574.8 - Mutex contention and increased hard parse time due to ILM (segment-access tracking) checking with partitioned objects, fixed in 12.2
Document 19790972.8 - "library cache lock" waits due to DBMS_STATS gather of stats for a subpartition, fixed in 12.2

Server Manageability (SVRMAN)

Bug 21521882 - SQLT CAUSES ORA-00600: [KGHSTACK_UNDERFLOW_INTERNAL_1]
  duplicate of Bug 19593445 - SR12.2CDBCONC3 - TRC - KPDBSWITCH
Document 18148383.8 AWR snapshots stopped , MMON hung with "EMON to process ntnfs" - affected 12.1.0.1, fixed in 12.1.0.2
Bug 20976392 - AWR REPORT: NEGATIVE OR WRONG VALUES IN %TOTAL OF UNOPTIMIZED READS
Document 2016112.1 - Replaying a PRE-12C Capture On 12.1.0.2.0 Encounters Unexpected ORA-1000 Errors
Bug 21117072 - DBREPLAY PATCH BUNDLE 1 FOR 12.1.0.2 , RAT Patch Bundle 1 for 12.1.0.2 is mandatory LGWR
Bug 23501117 - WORKLOAD REPLAY SKIPS USERCALLS FOR WORKLOAD CAPTURED UNDER 11.2.0.4
Document 22345045.8 - ORA-600 [kewrspbr_2: wrong last partition] in AWR internal tables after upgrading to 12.1.0.2
Multiple LGWR

Document 1968563.1 Hang Waiting on 'LGWR worker group ordering' with Deadlock Between LGWR (Log Writer) Slaves (LG0n) when Using Multiple LGWR Processes
Document 1957710.1 ALERT: Bug 21915719 Database hang or may fail to OPEN in 12c IBM AIX or HPUX Itanium - ORA-742, DEADLOCK or ORA-600 [kcrfrgv_nextlwn_scn] ORA-600

Exadata/In-memory/Multitenant

Document 21553476.8 Wrong Results using aggregations of CASE expression with fix of Bug 20003240 present in Exadata
Bug 19130972 - EXTREMELY LONG PARSE TIME FOR STAR QUERY (For In-memory DB, fixed in 12.1.0.2 DBBP 3)
Bug 17439841 - IMC DYNAMIC SAMPLING CAUSE "CURSOR: PIN S WAIT ON X" ON PARALLEL QUERY - affected 12.1.0.2, fixed in 12.1.0.2
Bug 21445204 - PARSING OF A QUERY TAKES LONG TIME WITH IMC
Document 21153142.8 - Row cache lock self deadlock accessing seed PDB, fixed in 12.2.
Bug 20766944 - QUERIES INVOLVING INT$DBA_CONSTRAINTS TAKE A LOT OF TIME, fixed in 12.2.
Document 17805926.8 - Parameter changes at PDB level affect other PDBs, fixed in 12.2

Popular Documents for Known issues/Bugs

Document 2034610.1 Things to Consider Before Upgrading to 12.1.0.2 to Avoid Poor Performance or Wrong Results
Document 2035898.1 Patches to Consider for 12.1.0.2 to Avoid Problems with SQL Plan Management (SPM)
Document 2107602.1 Things to Consider When Using Incremental Statistics
Document 1683802.1 12.1.0.2 Patch Set - List of Bug Fixes by Problem Type
Document 1924126.1 12.1.0.2 Patch Set Updates - List of Fixes in each PSU

Port-Specific

Document 1970525.1 Things to Consider to Avoid RDBMS Performance Problems on SPARC Platforms Using Oracle 12.1.0.2

Reference documents covering 12c new features

The following list of documents cover many of the features that have been introduced or enhanced in 12c and as provided to aid re-discovery:

Document 2031605.1 Adaptive Query Optimization
Document 2002108.1 Dynamic Sampling Level Is Changed Automatically in 12C
Document 2033658.1 Dictionary Queries Running Slow in 12C PDBs
Document 2002089.1 High Latch Free Waits on 'Result Cache: RC Latch' In 12C when RESULT_CACHE_MODE = MANUAL
Document 2004828.1 ORA-20002: Unable To Export Table Stats Using DBMS_STATS Package In 12c Database
Document 2051004.1 ORA-12012 ORA-20000 During Automatic Statistics Collection Job in 12C With Concurrent Option Enabled
Document 1955319.1 Huge Trace Files Created Containing "----- Cursor Obsoletion Dump sql_id=%s -----" From 12.1.0.2
Document 2053877.1 Wrong Results (0 Rows) Returned for Query that Includes Subquery Containing AND ROWNUM when OPTIMIZER_ADAPTIVE_FEATURES = TRUE
Document 2041541.1 Gather_Database_Stats_Job_Proc Taking More Time in 12.1.0.2 Than 11.2.0.4

Documentation

Database SQL Tuning Guide 12.1: http://docs.oracle.com/database/121/TGSQL/toc.htm
Database Performance Tuning Guide: http://docs.oracle.com/database/121/TGDBA/toc.htm
Database Testing Guide (RAT): http://docs.oracle.com/database/121/RATUG/toc.htm

参考：
Commonly Reported Known Issues for Database and Query Performance Reported in 12C (Doc ID 2097793.1 INTERNAL)
Documented Database Bugs With High “Solved SR” Count (Doc ID 2099231.1 INTERNAL)

自由是为自觉的人准备的，可往往少数不自觉的人破坏了大部分人的自由。

1月15日，有一段航拍杭州萧山机场飞机降落的视频，在飞友圈中激起很多反响。

随机，公安机关介入调查：

很快，公安部出台了《治安管理处罚法（修订公开征求意见稿）》，如无意外，一个月后将通过并生效。

飞友们所担心的“一刀切”的管理办法很快就会来临。所谓一刀切，就是没有得到允许，不能飞行。除非是在以下情况下：
1. 在室内运行的无人机；
2. 在视距内运行（半径≤500米；相对高度≤120米）的微型无人机(空机重≤7公斤)；
3. 在人烟稀少、空旷的非人口稠密区进行试验的无人机

这些条件就大大减少了玩无人机的乐趣。如小于120米的高度，基本市区内的很多大楼都是这个高度，自动返航的时候，往往小于120米就会撞楼。

一刀切从本质上来说，就是懒政。

我试着和微信群里面的一些朋友聊天，我认为无人机是个新鲜事物，进步的事物，应该得到保护。而在后续制定规则时，传统的民航部门往往据有话语权。这是不合理的。新鲜事物应该得到保护，应该在规则的制定中更加积极的融入其中，扮演更多的角色。

电灯泡不应该被蜡烛送上绞刑台。

逆向思维的说，我无人机为什么要避让你民航，你民航有告诉我你的升降高度吗？当然，正常情况下，这样的话往往是民航说出来的。

我的想法是，这件事件上，我们不应该仅仅是指责当时在萧山机场拍飞机降落的飞友：
1.为什么要在机场附近飞无人机
2.就算你在机场附近飞，为什么还要拍航路上的飞机降落
2.就算你拍了航路上降落的飞机，为什么还要放到网上来

这种指责的逻辑，其实和指责陈冠希老师拍照片出名是一个道理，为什么你要拍；如果拍了，你就不应该保存在电脑上；就算保存在电脑上，你的电脑不应该拿去修。

我觉得正确的做法应该是无人机行业和民航，需要积极的合作，共同制定相关规则，并且通过国家的认证。如机场几公里不能飞，跑道延伸朝向的几公里不能飞，而不是大疆只是划了一个5公里的圈。飞机在几公里范围能不能下降到多高的高度，无人机在几公里的范围内不能超越多高的高度。

说起认证，当前我国的认证是“三国演义”，都是行业认证，不是国家标准：
1. 由民航总局发的AOPA证书。主要针对大于7kg，超过120米高度，500米距离的无人机。
2. 由国家体育总局发的ASFC证书。主要针对小型无人机，穿越机，航模等等，听说在上海地区比较认可该证书。
3. 有大疆旗下的慧飞公司颁发的UTC证书。目前只有植保机的证书，后续会增加摄影机的证书。

由于三家证书都仅仅是行业证书，所以都互相撕逼，互不承认对方。三家证书都有不少培训机构，诋毁对方，以获得圈钱的优势，已经不是什么奇怪的事情。

所幸，大疆将在技术上做出改进，将推出全新的ADS-B广播式预警系统，帮助航拍飞行器的操作人员避开民航客机。但这仅仅是在技术上，说到指定标准，还需要积极的和民航以及其他部门的配合。但是与肉食者鄙的部门配合，你也知道，在我国是一件非常困难的事情。请证明你妈是你妈给我看看。谢谢！

在oracle数据库hang的情况下，我们可以用sqlplus -prelim / as sysdba登录数据库，进行一些收集信息的操作，也可以进行shutdown database的操作。这里需要注意几点：

1. process满是可以用sqlplus -prelim / as sysdba登录的

2. 从11.2.0.2开始，sqlplus -prelim / as sysdba是不能收集hanganalyze的信息，即使hanganalyze命令运行成功，但是在trace文件中看不到对应的信息，只能看到如下的报错：

ERROR: Can not perform hang analysis dump without a process state object and a session state object.
( process=(nil), sess=(nil) )

3. sqlplus -prelim / as sysdba可以收集process state dump，system state dump，dump errorstack，short_stack的操作。

参考：How to Collect Diagnostics for Database Hanging Issues (Doc ID 452358.1)

对于大表的统计信息收集，我们可以加degree参数，使得扫描大表的时候，进行并行扫描，加快扫描速度。
但是这在收集的时候，还是进行一个表一个表的扫描。并没有并发的扫描各个表。在oracle 11.2.0.2之后，就有了一个参数，可以并发扫描表（或者分区），这就是CONCURRENT参数。你可以通过

SELECT DBMS_STATS.get_prefs('CONCURRENT') FROM dual;

看到你的数据库是否启用了CONCURRENT收集统计信息。

开启方式为:

SQL> begin
  2   dbms_stats.set_global_prefs('CONCURRENT','TRUE');
  3  end;
  4  /

开启concurrent之后，收集统计信息就会以并发的形式进行，会并发出多个job进程。
其收集方式如下图：

从测试结果看，启用concurrent的收集统计信息速度对比：
schema级别的收集，XXX_SCHEMA下有400个多segment，大约20多GB：
默认：

exec dbms_stats.gather_schema_stats(ownname => 'XXX_SCHEMA');
--263秒

开启8个并发：

exec dbms_stats.gather_schema_stats(ownname => 'XXX_SCHEMA',degree => 8);
--95秒。

开启concurrent+8个并发：

begin
dbms_stats.set_global_prefs('CONCURRENT','TRUE');
end;

exec dbms_stats.gather_schema_stats(ownname => 'XXX_SCHEMA',degree => 8);
--61秒

database级别的收集：（600多G数据，9万多个segment）
默认：

exec sys.dbms_stats.gather_database_stats;
--9小时

开启concurrent+8个并发：

begin
dbms_stats.set_global_prefs('CONCURRENT','TRUE');
end;


exec dbms_stats.sys.dbms_stats.gather_database_stats(degree => 8);
--4小时

需要注意的是：
1. 用concurrent收集统计信息，需要收集统计信息用户具有以下权限：
CREATE JOB
MANAGE SCHEDULER
MANAGE ANY QUEUE
即使是该用户具有了dba角色，也还是需要显式授权上述权限。
不然执行job的时候，可能会报错
ORA-27486 insufficient privileges和ORA-20000: Statistics collection failed for 32235 objects in the database

2. concurrent不能控制多少的并发度，所以如果数据库的初始化参数job_queue_processes设置的太高，（注意，在11.2.0.3之后，这个值的默认值是1000，所以就可能并发出1000个job。）
如在测试时，某测试库设置了60个job_queue_processes的时候，数据库中就会并发出60个job来收集统计信息。此时的top情况，可以看到CPU的user部分基本已经在90%以上了。

top - 11:31:08 up 118 days, 19:28,  2 users,  load average: 30.65, 28.13, 25.64
Tasks: 728 total,  50 running, 678 sleeping,   0 stopped,   0 zombie
Cpu(s): 91.7%us,  7.5%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  0.7%si,  0.0%st
Mem:  16467504k total, 16375356k used,    92148k free,   119896k buffers
Swap:  6094844k total,  2106168k used,  3988676k free,  8952852k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
19295 ora       20   0 8856m 154m 119m R 22.9  1.0   0:01.44 ora_j030_mydb12
18503 ora       20   0 8856m 583m 548m R 21.0  3.6   0:25.02 ora_j032_mydb12
19042 ora       20   0 8856m 332m 297m R 21.0  2.1   0:09.21 ora_j026_mydb12
19162 ora       20   0 8856m 273m 238m R 21.0  1.7   0:05.51 ora_j020_mydb12
19203 ora       20   0 8856m 198m 164m R 21.0  1.2   0:02.66 ora_j035_mydb12
19211 ora       20   0 8856m 243m 208m R 21.0  1.5   0:04.03 ora_j024_mydb12
18550 ora       20   0 8856m 526m 491m R 20.0  3.3   0:21.06 ora_j033_mydb12
19009 ora       20   0 8856m 305m 271m R 20.0  1.9   0:07.84 ora_j031_mydb12
18792 ora       20   0 8857m 502m 467m R 19.6  3.1   0:18.23 ora_j022_mydb12
19199 ora       20   0 8856m 204m 169m R 19.3  1.3   0:03.31 ora_j025_mydb12
19137 ora       20   0 8857m 401m 367m R 19.0  2.5   0:06.67 ora_j011_mydb12
14518 ora       20   0 8857m 3.7g 3.6g R 18.3 23.3   1:25.49 ora_j003_mydb12
...
19128 ora       20   0 8857m 257m 222m R 17.0  1.6   0:04.57 ora_j034_mydb12
19255 ora       20   0 8856m 208m 173m R 17.0  1.3   0:02.79 ora_j000_mydb12
19065 ora       20   0 8856m 437m 402m R 16.7  2.7   0:09.31 ora_j001_mydb12
19073 ora       20   0 8856m 262m 227m R 16.7  1.6   0:05.53 ora_j038_mydb12
19195 ora       20   0 8848m 246m 215m R 16.7  1.5   0:04.21 ora_j004_mydb12
19112 ora       20   0 8857m 297m 262m D 16.4  1.9   0:06.68 ora_j017_mydb12
19299 ora       20   0 8856m 155m 120m R 16.4  1.0   0:01.21 ora_j037_mydb12
12088 ora       20   0 8872m 1.4g 1.3g R 16.0  8.8   6:59.12 ora_j021_mydb12
19108 ora       20   0 8856m 310m 275m R 16.0  1.9   0:06.90 ora_j006_mydb12
19191 ora       20   0 8856m 233m 198m R 16.0  1.5   0:04.01 ora_j016_mydb12
19259 ora       20   0 8829m 174m 163m R 15.7  1.1   0:02.84 ora_j008_mydb12
18536 ora       20   0 8857m 516m 481m R 15.4  3.2   0:19.72 ora_j040_mydb12
18939 ora       20   0 8856m 322m 287m R 15.4  2.0   0:07.44 ora_j039_mydb12

所以开启concurrent的另外一个建议，就是使用resource manager。

3. 观察concurrent收集的进度：

select job_name, state, comments
from dba_scheduler_jobs
where job_class like 'CONC%';

select state,count(*)
from dba_scheduler_jobs
where job_class like 'CONC%';
group by state;

4. 当启用concurrent的时候，同时再使用并行，建议将PARALLEL_ADAPTIVE_MULTI_USER设置成false，关闭并发度的自适应调整。
默认值是true，当使用默认值时，使自适应算法，在查询开始时基于系统负载来自动减少被要求的并行度。实际的并行度基于默认、来自表或hints的并行度，然后除以一个缩减因数。该算法假设系统已经在单用户环境下进行了最优调整。表和hints用默认的并行度

5. EBS系统应用是采用自己的并发管理器（FND_STATS）来收集统计信息，而收集统计信息用户往往是没有显式授权CREATE JOB、MANAGE SCHEDULER、MANAGE ANY QUEUE的。且EBS中用户众多，不可能为这些应用用户都显式授权。
所以在EBS中不能开启concurrent参数。EBS的安装文档中（Doc ID 396009.1），也是说将数据上收集统计信息的功能关闭的（_optimizer_autostats_job=false）

参考：
https://blogs.oracle.com/optimizer/entry/gathering_optimizer_statistics_is_one
http://blog.csdn.net/lukeUnique/article/details/51705922
Doc ID 1555451.1 – FAQ: Gathering Concurrent Statistics Using DBMS_STATS Frequently Asked Questions
Doc ID 396009.1 – Database Initialization Parameters for Oracle E-Business Suite Release 12

LAST UPDATE:

Dec 13, 2016

APPLIES TO:

Oracle Database - Enterprise Edition - Version 12.1.0.1 to 12.1.0.2 [Release 12.1]
Information in this document applies to any platform.

PURPOSE:

In recent quarters, during non-code closure bug review for Performance, it was found that more than 50% of duplicates (36,96) closed by Sustaining Engineering (SE) belonged to version 12.1. As a result this document was created to list most commonly reported and share this with Tier-1 engineers so that they could check this before logging any new bugs. Thus the Goal of this document is to provide a list of known bugs reported in 12C for database & SQL performance for support analysts to check before logging new bugs.

In addition to the bugs listed in this article, there is also a useful list of Documented Database Bugs With High "Solved SR" Count where a high number of Service Requests means that there are more than 50 "Solved SR" entries for the bug - ie: all bugs in this doc have > 50 "Solved SR" entries.” :

Document 2099231.1 Documented Database Bugs With High "Solved SR" Count

DETAILS:
Query Optimizer / SQL Execution

Bug 20271226 - QUERY INVOLVING VIRTUAL COLUMN AND PRIMARY KEY CONSTRAINT CRASHES
Document 19046459.8 - Inconsistent behavior of OJPPD
Document 22077191.8 - Create Table As Select of Insert Select Statement on 12.1 is Much Slower Than on 11.2
Bug 20597568 - PJE INCORRECTLY APPLIED TO A CONNECT BY QUERY
Document 18456944.8 - Suboptimal plan for query fetching ROWID from nested VIEW with fix 10129357
Bug 20355502 - QUERY PARSE NEVER ENDS ( BURNING CPU ALL THE TIME)
Document 20355502.8 Limit number of branches on non-cost based OR expansion
Document 20636003.8 - Slow Parsing caused by Dynamic Sampling (DS_SRV) queries in 12.1.0.2
Bug 22513913 - QUERY FAILS WITH ORA-07445: [KKOSJT()+281] WHEN USING DATABASE LINK
Bug 22020067 - UPGRADE 11.2.0.2 TO 11.2.0.4 SCALAR SUBQUERY UNNEST DISABLED
Bug 21099502 - JPPD Not Happening In UNION ALL View Having Group-by and Aggregates
Bug 22862828 - Regression with 22706363, JPPD Does Not Occur Despite the Fix Control 9380298 is ON
Bug 19295003 - High CPU While Parsing Huge SQL [kkqtutlTravOptAndReplaceOJNNCols]
Document 21091518.8 - Suboptimal plan for SQLs using UNION-ALL with bug fix 18304693 enabled
Document 22113854.8 - Query Against ALL_SYNONYMS Runs Slow in 12C
Document 21871902.8 - SELECT query fails with ORA-7445 [qerixRestoreFetchState2] - superseded by
Document 22255113.8 - High parse time with high memory and CPU usage
Document 22339954.8 - Bug 22339954 - High Parse Time for Query Using UNPIVOT Operator
Document 19490852.8 - Excessive "library cache lock" waits for DML with PARALLEL hint when parallel DML is disabled
Bug 20226806 - QUERY AGAINST ALL_CONSTRAINTS AND ALL_CONS_COLUMNS RUNS SLOWER IN 12.1.0.2
duplicate of Bug 20355502 - QUERY PARSE NEVER ENDS ( BURNING CPU ALL THE TIME)
Document 20118383.8 - Long query parse time in 12.1 when many histograms are involved - superseded by
Document 18795224.8 - Hard parse time increases with fix 12341619 enabled, fixed in 12.2
Document 19475484.8 - Cardinality of 0 for range predicate with fix for bug 6062266 present (default), fixed in 12.2
Document 2182951.1 Higher Elapsed Time after Updating from 11.2.0.4 to 12.1.0.2
Document 18498878.8 - medium size tables do not cached consistently causing unnecessary waits on direct path read, fixed in 12.2
Bug 23516956 - DYNAMIC SAMPLING QUERIES CONTAINS INCORRECT HINTS
duplicate of Document 19631234.8 - Suboptimal execution plan for Dynamic Sampling Queries
Bug 20503656 - Remote SQLs having group by with bind variables throw ORA-00979, fixed in 12.2
Bug 19047578 - Optimizer No Longer Uses Function Based Index When CURSOR_SHARING=FORCE
Document 22734628.8 - Wrong results from UNION ALL using OJPPD with cost based transformation disabled, fixed in 12.2
Bug 21839477 - ORA-7445 [QESDCF_DFB_RESET] WITH FIX FOR BUG:20118383 ON, fixed in 12.2
Document 20774515.8 - Wrong results with partial join evaluation, fixed in 12.2
Bug 21303294 - Wrong Result Due to Lost OR Predicate in Bitmap Plan, fixed in 12.2
Document 22951825.8 - Wrong Results with JPPD, Concatenation and Projection Pushdown, fixed in 12.2
Bug 19847091 - HUGE INLIST SQL HANGS DURING PARSE
superseded by Bug 20384335 - CPU REGRESSION DUE TO PLAN CHANGE IN ONE SELECT SQL WITH IN PREDICATE, fixed in 12.2

SQL Plan Management (SPM)

Document 20877664.8 - SQL Plan Management Slow with High Shared Pool Allocations
Document 21075138.8 - SPM does not reproduce plan with SORT UNIQUE, affected from 11.2.0.4 and fixed in 12.2 only
Document 20978266.8 - SPM: SQL not using plan in plan baselines and plans showing as not reproducible - superseded, fixed in 12.2
Document 19141838.8 - ORA-600 [qksanGetTextStr:1] from SQL Plan Management after Upgrade to 12.1
Document 18961555.8 - Static PL/SQL baseline reproduction broken by fix for bug 18020394, fixed in 12.2
Document 21463894.8 - Failure to reproduce plan with fix for bug 20978266, fixed in 12.2
Document 2039379.1 ORA-04024: Self-deadlock detected while trying to mutex pin cursor" on AUD_OBJECT_OPT$ With SQL Plan Management (SPM) Enabled

Wrong Results

Document 20214168.8 - Wrong Results using aggregations of CASE expression with fix of Bug 20003240 present
Bug 21971099 - 12C WRONG CARDINALITY FROM SQL ANALYTIC WINDOWS FUNCTIONS
Document 16191689.8 - Wrong resilts from projection pruning with XML and NESTED LOOPS
Bug 18302923 - WRONG ESTIMATE CARDINALITY IN HASH GROUP BY OR HASH JOIN
Bug 21220620 - WRONG RESULT ON 12C WHEN QUERYING PARTITIONED TABLE WITH DISTINCT CLAUSE
Document 22173980.8 - Wrong results (number of rows) from HASH join when "_rowsets_enabled" = true in 12c (default)
Bug 20871556 - WRONG RESULTS WITH OPTIMIZER_FEATURES_ENABLE SET TO 12.1.0.1 OR 12.1.0.2
Bug 21387771 - 12C WRONG RESULT WITH OR CONDITION EVEN AFTER PATCHING FOR BUG:20871556
Bug 22660003 - WRONG RESULTS WHEN UNNESTING SET SUBQUERY WITH CORRELATED SUBQUERY IN A BRANCH
Bug 22373397 - WRONG RESULTS DUE TO MISSING PREDICATE DURING BITMAP OR EXPANSION
Bug 22365117 - SQL QUERY COMBINING TABLE FUNCTION WITH JOIN YIELDS WRONG JOIN RESULTS
Bug 20176675 - Wrong results for SQLs using ROWNUM<=N when Scalar Subquery is Unnested (VW_SSQ_1)
Document 19072979.8 - Wrong results with HASH JOIN and parameter "_rowsets_enable"
Document 22338374.8 - ORA-7445 [kkoiqb] or ORA-979 or Wrong Results when using scalar sub-queries
Document 22365117.8 - Wrong Results / ORA-7445 from Query with Table Function
Bug 19318508 - WRONG RESULT IN 12.1 WITH NULL ACCEPTING SEMIJOIN - fixed in 12.2
Bug 21962459 - WRONG RESULTS WITH FIXED CHAR COLUMN AFTER 12C MIGRATION WITH PARTIAL JOIN EVAL
Bug 23019286 - CARDINALITY ESTIMATE WRONG WITH HISTOGRAM ON COLUMN GROUP ON CHAR/NCHAR TYPES, fixed in 12.2
Bug 23253821 - Wrong Results While Running Merge Statement in Parallel, fixed in 12.2
Document 18485835.8 - Wrong results from semi-join elimination if fix 18115594 enabled, fixed in 12.2
Document 18650065.8 - Wrong Results on Query with Subquery Using OR EXISTS or Null Accepting Semijoin, fixed in 12.2
Document 19567916.8 - Wrong results when GROUP BY uses nested queries in 12.1.0.2 - superseded by
Document 20508819.8 - Wrong results/dump/ora-932 from GROUP BY query when "_optimizer_aggr_groupby_elim"=true - superseded by
Document 21826068.8 - Wrong Results when _optimizer_aggr_groupby_elim=true
Document 20634449.8 - Wrong results from OUTER JOIN with a bind variable and a GROUP BY clause in 12.1.0.2
Bug 20162495 - WRONG RESULTS FROM NULL ACCEPTING SEMI-JOIN, fixed in 12.2.

Statistics

Bug 22081245 - COPY_TABLE_STATS DOES NOT WORK PROPERLY FOR TABLES WITH SUB PARTITIONS
Bug 22276972 - DBMS_STATS.COPY_TABLE_STATS INCORRECTLY ADJUST MIN/MAX FOR PARTITION COLUMNS
Document 19450139.8 Slow gather table stats with incremental stats enabled
Bug 21258096 - UNNECESSARY INCREMENTAL STATISTICS GATHERED FOR UNCHANGED PARTITIONS DUE TO HISTOGRAMS
Bug 23100700 - PERFORMANCE ISSUE WITH RECLAIM_SYNOPSIS_SPACE, fixed in 12.2
Document 21171382.8 - Enhancement: AUTO_STAT_EXTENSIONS preference on DBMS_STATS - Enhancement To turn off automatic creation of extended statistics in 12c
Document 21498770.8 - automatic incremental statistics job taking more time with fix 16851194, fixed in 12.2
Document 22984335.8 - Unnecessary Incremental Partition Gathers/Histogram Regathers

Errors

Document 20804063.8 ORA-1499 as REGEXP_REPLACE is allowed to be used in Function-based indexes (FBI)
Document 17609164.8 ORA-600 [kkqctmdcq: Query Block Could] from ANSI JOIN with no a join predicate
Document 21482099.8 ORA-7445 [opitca] or ORA-932 errors from aggregate GROUP BY elimination
Document 21756734.8 - ORA-600 [kkqcsnlopcbkint : 1] from cost based query transformation
Bug 22566555 - ORA-00600 [KKQCSCPOPNWITHMAP: 0] FOR SUBQUERY FACTORING QUERY WITH DISTINCT
Bug 21377051 - ORA-600 [QKAFFSINDEX1] FROM DELETE STATEMENT
Document 21188532.8 - Unexpected ORA-979 with fix for bug 20177858 - superseded by
Bug 23343584 - GATHER_TABLE_STATS FAILS WITH ORA-6502/ORA-6512
duplicate of Bug 22928015 - GATHER DATABASE STATS IS RUNNING VERY SLOWLY ON A RAC ENVIRONMENT
Document 21038926.8 - ORA-7445 [qesdcf_dfb_reset] with fix for bug 20118383 present, fixed in 12.2
Document 18405192.8 - ORA-7445 under qervwFetch() or qervwRestoreViewBufPtrs() when deleting from view with an INSTEAD OF trigger
Document 21968539.8 - ORA-600 [kkqcscpopnwithmap: 0]
Document 18201352.8 - ORA-7445 [qertbStart] or similar errors from query with DISTINCT and partial join evaluation (PJE) transformation
Document 19472320.8 - ORA-600 [kkqtSetOp.1] from join factorization on encrypted column
Bug 22394273 - ORA-600 [QESMMCVALSTAT4] FROM SELECT STATEMENT
Document 21529241.8 - DBMS_STATS ORA-6502: "PL/SQL: numeric or value error"
Document 20505851.8 - ORA-600 / ORA-7445 qksqbApplyToQbcLoc from WITH query that has duplicate predicates
Bug 19952510 - ORA 600 [QERSCALLOCATE: BUFFER SIZE LIMIT] AND ORA 600 [KEUUXS_1]
Bug 21274291 - ORA-600 :[17147] AND [ORA-600 :[KGHALF] DURING AN INSERT
Bug 21524270 - ORA-28115 ON ORACLE 12C WITH VPD IN MERGE STMT, BUT INSERT SUCCEEDS
Bug 20660917 - INSTEAD OF TRIGGER IS FIRED TWICE INSTEAD OF ONCE WITH FIX TO 13812807, Causes ORA-07445 [kxtifir] in 12.1.0.2 - fixed in 12.2.

Adaptive Query Optimization

Bug 18745156 - ADAPTIVE DYNAMIC SAMPLING CAUSES BAD CARDINALITY ESTIMATE
Bug 16033838 - TST&PERF: ADAPTIVE JOINS LEADS TO WORSE PLAN FOR QUERY B4TKVSMPFSP85
Document 20465582.8 High parse time in 12c for multi-table join SQL with SQL plan directives enabled - superseded
Document 20807398.8 ORA-600 [kgl-hash-collision] with fix to Bug 20465582 installed
Document 18430870.8 Adaptive Plan and Left Join Give Wrong Result
Bug 21912039 : GSIAS: PERF REGRESSION: ADAPTIVE PLAN SQL_ID DN50XQR69FJ0F GETS WORSE
  duplicate of Bug 20243268 : EM QUERY WITH SQL_ID 4RQ83FNXTF39U PERFORMS POORLY ON ORACLE 12C RELATIVE TO 11G
Bug 19731829 - ISSUES WITH PACK AND UNPACK OF SQL PLAN DIRECTIVES
Document 20370037.8 - KGLH0 growth leading to ORA-4031 by cardinality feedback, fixed in 12.2
Document 20413540.8 - Excessive executions of SQL frjd8zfy2jfdq

Library cache / Rowcache / Shared Cursors / Dictionary / Buffer cache

Document 19450314.8 Unnecessary invalidations in 12c
Bug 21153142 - ROW CACHE LOCK SELF DEADLOCK ACCESSING SEED PDB
Bug 22081947 - ORA-4023 MAY OCCUR IN ACTIVE DATA GUARD ENVIRONMENTS
Bug 12387079 - THE CHILD CURSOR IS INCREASED WHEN THE CURSOR IS KEPT AND EXECUTED DDL
  superseded by Bug 19239846 - FIX FOR Bug 12387079 NEEDS TO BE RE-WORKED
Bug 12320556 - HIGH VERSION COUNTS OCCUR DUE TO AUTH_CHECK_MISMATCH, INSUFF_PRIVS_REM=Y
  superseded by Bug 21515534 - QUERY USING 2 REMOTE DB NOT SHARED - AUTH_CHECK_MISMATCH ,INSUFF_PRIVS_REM
Document 21515534.8 Query referencing multiple remote databases not shared with reason AUTH_CHECK_MISMATCH INSUFF_PRIVS_REM
Document 20907061.8 High number of executions for recursive call on col$
Document 20476175.8 High VERSION_COUNT (in V$SQLAREA) for query with OPT_PARAM('_fix_control') hint
Bug 21799609 - ORA-04024 DEADLOCK ON STARTUP ON SYS.ECOL$ ON LOAD HISTOGRAMS
  duplicate of Bug 19469538 - LOADING OF DATA IN ECOL$ TABLE IS NON-OPTIMAL FOR QUERIES
Bug 22586498 - HUGE M000 TRACEFILE DUE TO OBSOLETE CURSOR DUMPS
Document 20906941.8 - DBW0 spins with high CPU
Bug 17700290 - TST&PERF: LIBRARY CACHE MUTEX WAIT TIME INCREASED HUGELY IN MAIN - affected 12.1.0.2, fixed in 12.2 only
Bug 22733141 - GATHERING STATS ON X$KQLFBC HANGS
Bug 23098370 - DBWR CAN ISSUE MORE THAN SSTMXIOB IO'S
Bug 23103188 - Incorrect ORA-1031 or ORA-942 during Grant due to 22677790, fixed in 12.2
Bug 19340498 - CDB:NO ROWS RETURNED WHEN QUERYING V$SQL_SHARED_MEMORY INSIDE A PDB
Bug 23514710 - CROSS-CONTAINER FIXED TABLE NOT OBSOLETED WHEN PARENT IS MARKED OBSOLETE in ADG Env
Document 19392364.8 - Process spin in kkscsFindMatchingRange() with adaptive cursor sharing, fixed in 12.2
Document 2096561.1 - High Amount Of Shared Memory Allocated Into KGLH0 Heap In 12.1.0.2
Document 2119923.1 - Shared Pool from KGLH0 constantly growing causing ORA-04031 and Latch contention
Document 23168642.8 - Sporadic ORA-600 [kglunpin-bad-pin] / ORA-14403 / high 'library cache: mutex x' using partitions and deferred seg creation / ORA-600 [qesmascTrimLRU_1] with fix 21759047, fixed in 12.2
Document 21759047.8 - High 'library cache: mutex x' Contention when Many Sessions are Executing Cursors Concurrently Against a Partitioned Table - superseded, fixed in 12.2
Document 14380605.8 - High "library cache lock", "cursor: pin S wait on X" and "library cache: mutex X" waits, fixed in 12.2
Document 19822816.8 - High parse time for SQL with PIVOT and binds (can block LGWR on "library cache lock"), fixed in 12.2
Document 13542050.8 - 'library cache: mutex X' waits : A mutex related hang with holder around 65534 (0xfffe), fixed in 12.2
Document 21834574.8 - Mutex contention and increased hard parse time due to ILM (segment-access tracking) checking with partitioned objects, fixed in 12.2
Document 19790972.8 - "library cache lock" waits due to DBMS_STATS gather of stats for a subpartition, fixed in 12.2

Server Manageability (SVRMAN)

Bug 21521882 - SQLT CAUSES ORA-00600: [KGHSTACK_UNDERFLOW_INTERNAL_1]
  duplicate of Bug 19593445 - SR12.2CDBCONC3 - TRC - KPDBSWITCH
Document 18148383.8 AWR snapshots stopped , MMON hung with "EMON to process ntnfs" - affected 12.1.0.1, fixed in 12.1.0.2
Bug 20976392 - AWR REPORT: NEGATIVE OR WRONG VALUES IN %TOTAL OF UNOPTIMIZED READS
Document 2016112.1 - Replaying a PRE-12C Capture On 12.1.0.2.0 Encounters Unexpected ORA-1000 Errors
Bug 21117072 - DBREPLAY PATCH BUNDLE 1 FOR 12.1.0.2 , RAT Patch Bundle 1 for 12.1.0.2 is mandatory LGWR
Bug 23501117 - WORKLOAD REPLAY SKIPS USERCALLS FOR WORKLOAD CAPTURED UNDER 11.2.0.4
Document 22345045.8 - ORA-600 [kewrspbr_2: wrong last partition] in AWR internal tables after upgrading to 12.1.0.2
Multiple LGWR

Document 1968563.1 Hang Waiting on 'LGWR worker group ordering' with Deadlock Between LGWR (Log Writer) Slaves (LG0n) when Using Multiple LGWR Processes
Document 1957710.1 ALERT: Bug 21915719 Database hang or may fail to OPEN in 12c IBM AIX or HPUX Itanium - ORA-742, DEADLOCK or ORA-600 [kcrfrgv_nextlwn_scn] ORA-600

Exadata/In-memory/Multitenant

Document 21553476.8 Wrong Results using aggregations of CASE expression with fix of Bug 20003240 present in Exadata
Bug 19130972 - EXTREMELY LONG PARSE TIME FOR STAR QUERY (For In-memory DB, fixed in 12.1.0.2 DBBP 3)
Bug 17439841 - IMC DYNAMIC SAMPLING CAUSE "CURSOR: PIN S WAIT ON X" ON PARALLEL QUERY - affected 12.1.0.2, fixed in 12.1.0.2
Bug 21445204 - PARSING OF A QUERY TAKES LONG TIME WITH IMC
Document 21153142.8 - Row cache lock self deadlock accessing seed PDB, fixed in 12.2.
Bug 20766944 - QUERIES INVOLVING INT$DBA_CONSTRAINTS TAKE A LOT OF TIME, fixed in 12.2.
Document 17805926.8 - Parameter changes at PDB level affect other PDBs, fixed in 12.2

Popular Documents for Known issues/Bugs

Document 2034610.1 Things to Consider Before Upgrading to 12.1.0.2 to Avoid Poor Performance or Wrong Results
Document 2035898.1 Patches to Consider for 12.1.0.2 to Avoid Problems with SQL Plan Management (SPM)
Document 2107602.1 Things to Consider When Using Incremental Statistics
Document 1683802.1 12.1.0.2 Patch Set - List of Bug Fixes by Problem Type
Document 1924126.1 12.1.0.2 Patch Set Updates - List of Fixes in each PSU

Port-Specific

Document 1970525.1 Things to Consider to Avoid RDBMS Performance Problems on SPARC Platforms Using Oracle 12.1.0.2

Reference documents covering 12c new features

The following list of documents cover many of the features that have been introduced or enhanced in 12c and as provided to aid re-discovery:

Document 2031605.1 Adaptive Query Optimization
Document 2002108.1 Dynamic Sampling Level Is Changed Automatically in 12C
Document 2033658.1 Dictionary Queries Running Slow in 12C PDBs
Document 2002089.1 High Latch Free Waits on 'Result Cache: RC Latch' In 12C when RESULT_CACHE_MODE = MANUAL
Document 2004828.1 ORA-20002: Unable To Export Table Stats Using DBMS_STATS Package In 12c Database
Document 2051004.1 ORA-12012 ORA-20000 During Automatic Statistics Collection Job in 12C With Concurrent Option Enabled
Document 1955319.1 Huge Trace Files Created Containing "----- Cursor Obsoletion Dump sql_id=%s -----" From 12.1.0.2
Document 2053877.1 Wrong Results (0 Rows) Returned for Query that Includes Subquery Containing AND ROWNUM when OPTIMIZER_ADAPTIVE_FEATURES = TRUE
Document 2041541.1 Gather_Database_Stats_Job_Proc Taking More Time in 12.1.0.2 Than 11.2.0.4

Documentation

Database SQL Tuning Guide 12.1: http://docs.oracle.com/database/121/TGSQL/toc.htm
Database Performance Tuning Guide: http://docs.oracle.com/database/121/TGDBA/toc.htm
Database Testing Guide (RAT): http://docs.oracle.com/database/121/RATUG/toc.htm

参考：
Commonly Reported Known Issues for Database and Query Performance Reported in 12C (Doc ID 2097793.1 INTERNAL)
Documented Database Bugs With High “Solved SR” Count (Doc ID 2099231.1 INTERNAL)

APPLIES TO:

Oracle Database - Enterprise Edition - Version 9.2.0.8 and later

PURPOSE:

This note lists "documented" database bugs that have been marked as the solution to a "high number of Service Requests".
For the purpose of this listing:
A "documented" bug means one with a bugno.8 KM document created from BugTag data.
A "high number of Service Requests" means that there are more than 50 "Solved SR" entries for the bug - ie: all bugs in this doc have > 50 "Solved SR" entries from the SR closure data.
It is suggested to restrict the list based on the version of interest, and then use the radio buttons to check on particular features / symptoms / facts linked to the bug descriptions.

The list includes some bugs with a "D" in the "NB" column - this is used to denote a bug fix that is DISABLED by default and so a customer may encounter that issue in DB versions where the bug is marked as fixed.

KNOWN BUGS:

'*' indicates that an alert exists for that issue.
'+' indicates a particularly notable issue / bug.
See Note:1944526.1 for details of other symbols used

参考：
Documented Database Bugs With High “Solved SR” Count (Doc ID 2099231.1 INTERNAL)

LAST UPDATE:

Jun 15, 2011

APPLIES TO:

Oracle Server - Enterprise Edition - Version: 9.2.0.1 to 11.1.0.8 - Release: 9.2 to 11.1
Information in this document applies to any platform.
Customers should have limited access to these scripts. There can be database hangs and impacts to performance running these too often.

PURPOSE:
There are a number of x$ queries in various notes in WebIV. This note is an attempt to collect the commonly used scripts for investigating Shared Pool problems in one place. Attached is a ZIP file with the common scripts for analysis of fragmentation and/or memory problems.

Click here (last updated 2-11-2009) to download the attached zip file.

SOFTWARE REQUIREMENTS/PREREQUISITES:

These scripts access data from the X$ dictionary tables directly.  To run the scripts you will need to login with SYS privileges.
CONFIGURING THE SAMPLE CODE

No special instructions for these scripts.   It may be necessary to adjust the spool output file to use a directory path where you have write privileges.

RUNNING THE SAMPLE CODE:
Scripts:

==>ChunkOverview.sql:
spools to chunkoverview.out

If only able to run one script on the X$ dictionary tables, run this one.  You will see overview information from V$SGA and a high level breakdown of the categories of memory chunks in the Shared pool.   You will also see a more detailed breakdown of chunks with summing up large chunks vs. small chunks.

==>ChunkClassBreakdown.sql:
spools to chunksummary.out

Provides just the high level breakdown of the categories of memory chunks in the Shared Pool.

General rules of thumb:
   a) if free memory (Tot Size) is low (less than 5mb or so) you
       may need to increase the shared_pool_size and shared_pool_reserved_size.
   b) if perm continually grows then it is possible you are seeing system memory leak.
   c) if freeabl and recr are always huge, this indicates that you have lots of cursor
       info stored that is not releasing.
   d) if free is huge but you are still getting 4031 errors, (you can correlate that
       with the reloads and invalids causing fragmentation)

  The key data from this high level look is free and freeable average chunk size.
  If that is in the 100s or even low 1000s of bytes, this points to excessive fragmentation.

==>ChunkByTypeClass.sql:
spools to chunkbytype.out

Shows a more detailed breakdown of what memory is used where in the Shared Pool showing both memory type and memory class.   This information not needed very often.

==>ChunkBreakdown.sql:
spools to chunks.out

Shows the lowest level information of on the memory chunks being used in the Shared Pool.   This information is not needed very often.

CAUTION:

This sample code is provided for educational purposes only and not supported by Oracle Support Services. It has been tested internally, however, and works as documented. We do not guarantee that it will work for you, so be sure to test it in your environment before relying on it.
Proofread this sample code before using it! Due to the differences in the way text editors, e-mail packages and operating systems handle text formatting (spaces, tabs and carriage returns), this sample code may not be in an executable state when you first receive it. Check over the sample code to ensure that errors of this type are corrected.

SAMPLE CODE:

The scripts are attached in a zip file as there are often problems between platforms with cut and paste from a note.

SAMPLE CODE OUTPUT:
ChunkOverview.sql spools to chunkoverview.out

Name BYTES Auto
---------------------------------------- ---------- ----
Fixed SGA Size 1334380 No
Redo Buffers 5844992 No
Buffer Cache Size 268435456 Yes
...

Chunk
Class     Num Chunks             Min Size            Max Size              Avg Size            Tot Size
---------- -------------------------- -------------------- ---------------------- -------------------- -----------------
recr                               60,248                       32               3,977,156                      969      58,395,008
perm                               474                            8               3,981,268               109,155      51,739,720
freeabl                          49,926                       16                  334,348                  1,823      91,062,956
free                                    841                       20               1,058,464                  2,198        1,849,228
R-freea                              102                       24                                                      24          24 2,448
R-free                                  51              212,888                   212,888             212,888      10,857,288
----------------
Total Alloc                                                                                                                      213,906,648

Bucket        From         Count          Biggest           AvgSize
-------------- ------------- --------------- ------------------ ------------
0 (<4400)                   0               805                   392             68
                               500                 11                   936          794
                            1,000                   2                1,276       1,142
                            1,500                   2                1,892       1,844
                            2,000                   7                2,144       2,097
                            2,500                   1                2,852       2,852
                            3,000                   2                3,260       3,146
**********                   ------------
sum                                            830

6+ (4108+)         6,000                   1                6,288       6,288
                           7,000                   1                7,576       7,576
                         12,000                   1             12,288      12,288
                         16,000                   1             16,504      16,504
                         21,000                   1             21,264      21,264
                         32,000                   1             32,888      32,888
                         71,000                   1             71,704      71,704
                         74,000                   1            74,544       74,544
                       454,000                   1          454,184     454,184
                    1,058,000                   1        1,058,464 1,058,464
**********                 ------------
sum                                             10

ChunkClassBreakdown.sql spools to chunksummary.out

Chunk
Class              Num Chunks             Min Size      Max Size      Avg Size      Tot Size
----------------- -------------------------- --------------- ---------------- ---------------- ----------------
recr                                        60,216                 32      3,977,156                 969     58,374,128
perm                                           473                   8      3,981,268          109,386     51,739,720
freeabl                                   49,879                 16         334,348             1,823      90,959,200
free                                             843                  20      1,172,680             2,341       1,973,864
R-freea                                       102                  24                  24                 24                2,448
R-free                                           51         212,888         212,888        212,888       10,857,288
----------------
Total Allo                                                                                                              213,906,648

ChunkByTypeClass.sql spools to chunkbytype.out

Allocation    Chunk
Subpool Type             Class          No. of Chunks     Min Size      Max Size     Avg Size     Tot Size
----------- ---------------- --------------- ---------------------- --------------- --------------- --------------- ---------------
1              CCursor        freeabl                             8976            1,072            3,616             1,187   10,660,112
1                                     recr                                  3511            1,072            1,072             1,072     3,763,792
***************                                                                                                                       ---------------
Total Mem                                                                                                                                       14,423,904


1              CPM trailer   perm                                      2                  8                   8                    8                 16
***************                                                                                                                      ---------------
Total Mem                                                                                                                                                    16


1              Cursor Stats freeabl                              302            4,096            4,096             4,096     1,236,992
1                                     recr                                       4            4,096            4,096             4,096          16,384
***************                                                                                                                      ---------------
Total Mem                                                                                                                                         1,253,376
....

ChunkBreakdown.sql spools to chunks.out

Subpool Allocation Type            NUM_CHUNKS      Min Size      Max Size     Avg Size     Tot Size
------------ ----------------------------- -------------------------- --------------- --------------- --------------- ----------------
1               CPM trailer                                                     2                   8                   8                   8                 16
1               kodosgi kodos                                               1                 16                 16                 16                 16
1               listener addres                                                1                 16                16                 16                 16
1               KSN WaitID                                                   3                  16                16                 16                 48
...
1               reserved stoppe                                         102                 24                24                 24             2,448
...

Attachments:
Various internal scripts – 02-11-2009(2.59 KB)

参考：
Common X$ dictionary table queries for ORA-4031 investigation (Doc ID 742575.1 INTERNAL)