weejar zhang – Page 52

Oracle GoldenGate Trail File

2013-03-20 by weejar zhang

Trail files are generated by both the original extract and the Data Pump (extract) process. Trail files are read by the Data Pump (extract) and Replicat (replicat) processes

Schema level flashback(闪回用户或方案)

2013-03-14 by weejar zhang

Technically there is no schema level flashback feature available. and flashback database is a binary operation, the bits and bytes of the flashed back data are identical to what they used to be, it is not a ‘logical’ flashback, it is a physical flashback. However, provided your recovery period does not include any data dictionary … Read more

Script: Who’s using a database link?(找出谁在使用dblink)

2018-11-012013-03-14 by weejar zhang

Every once in awhile it is useful to find out which sessions are using a database link in an Oracle database. It’s one of those things that you may not need very often, but when you do need it, it is usually rather important. Yong Huang includes this script on his website, and notes that … Read more

More about index

2013-03-252013-03-13 by weejar zhang

创建索引可以方便的给DB带来查询上的性能提升，但是DML时index的维护代价也是昂贵的。合理的创建索引，删除不必要的索引。

Tuning PGA Memory

2013-03-11 by weejar zhang

You can get the correct size of PGA using V$PGA_TARGET_ADVICE, dynamic performance view.

HAVING expression default Selectivity

2013-03-01 by weejar zhang

In some cases the query optimizer might can not accurately estimate cardinality (e.g. group by having or like with bind variables cause etc..),therefore the Cardinality estimates are based on default seletivity of build-in oracle coredefault seletivity(5%).

oracle forall instructs must be followed by DML

2013-02-26 by weejar zhang

Oracle BULK COLLECT and Oracle FORALL are the new features in Oracle 8i, 9i and 10g PL/SQL that can really make a different to you PL/SQL performance. The keyword FORALL instructs the PL/SQL engine to bulk-bind input collections before sending them to the SQL engine. Although the FORALL statement contains an iteration scheme, it is … Read more

goldengate extract process abending caused by nologging DDL

2013-09-102013-01-30 by weejar zhang

I use goldengate(for oracle) to do a SCHEMA synchronized,include DDL operrations. when the the EXTRACT process was running to capture the changes ,then if you try do a DDL such as “alter table t_a no logging” on the capture table will cause EXT process ABENDING, I hit these errors today. ogg version: Oracle GoldenGate Command … Read more

US7ASCII DMP 导入 ZHS16GBK DB 一方案

2014-06-132013-01-28 by weejar zhang

exp 时注意保证三处的字符集一致，对于本例的US7ASCII(10g) DMP 导入 ZHS16GBK DB (11g),采用了修改dmp文件中的两处字符集编号，最终解决了字符集乱码问题。

The lowercase and quotes table names may not be able to audit(小写表名可能不会审计)

2013-01-25 by weejar zhang

昨一好朋友问我开了审计，有些表但无审计记录。下面我来还原这个问题 db_version oracle 10201 for linux SQL> show parameter audit NAME TYPE VALUE ———————————— ———– —————————— audit_file_dest string /u1/oracle/admin/ORCL/adump audit_sys_operations boolean FALSE audit_syslog_level string audit_trail string DB, EXTENDED audit select any table by access; SQL> select os_username,username,terminal,timestamp,owner,obj_name,audit_option from DBA_AUDIT_TRAIL order by 4; OS_USERNAM USERNAME TERMINAL TIMESTAMP OWNER OBJ_NAME AUDIT_OPTION ———- ———- ———- ——————- —————————— … Read more

ORA-1688: unable to extend table SYS.WRH$_ACTIVE_SESSION_HISTORY

2013-01-22 by weejar zhang

1) Export the snapshots and then do a manual purge To purge the Table SYS.WRH$_ACTIVE_SESSION_HISTORY, you may first query the Snapshot History with the query below: select snap_id, begin_interval_time from sys.dba_hist_snapshot order by snap_id; Then, you choose the range of snapshot you want to delete, and you execute the following Procedure: exec dbms_workload_repository.drop_snapshot_range ( low_snap_id … Read more

batch change read only DB in mssql 2K

2013-01-22 by weejar zhang

I had an issue while dropping a mssql user today, I was unable to drop the user and it failed with the user in an read_only db. I had many db in the server(more than 200),and many read-only db,so To delete an user must setting there DB to read write status.

How TO Kill and Logout users in pts/* Linux

2013-01-21 by weejar zhang

In Linux, PTS stands for Pseudo Terminal Slave. PTS refers to a user currently logged in to your terminal using an SSH or telnet connection.

DB File Sequential and Scattered Reads

2013-01-17 by weejar zhang

Both “db file sequential read” and “db file scattered read” events signify time waited for I/O read requests to complete.

Changing SYS Password in RAC (修改SYS密码)

2013-01-10 by weejar zhang

We know that changed a normal user password has no diffrence between a single instance database and a RAC database,we just have to perform “alter user xxx identified by xxx” and the password will be cheanged.

Script: TOP logical read within a specific time period(指定时间逻辑读最多的对象)

2014-03-042013-01-09 by weejar zhang

根据AWR的收集信息查询出指定时间段内的逻辑读最高的几个对象，script

goldengate supports sync data from no-partition table to partition table(OGG同步非分区表到分区表)

2013-09-102013-01-07 by weejar zhang

OGG可以是否从SOURCE db 一个非分区表到TARGET db 的一个分区表的同步么？DDL/DML是否都可以？

How to limit program access to database(限止连接数据库使用程序)

2013-01-06 by weejar zhang

有时出于安全考虑限制个别用户只允许特定程序连接或连接数，比如下面的例子是只允许ANBOB用户使用pl/sql dev连接此数据库。

statement suspended, wait error to be cleared(二)

2013-01-05 by weejar zhang

Oracle Database provides a means for suspending, and later resuming,
the execution of large database operations in the event of space allocation failures.

本站2012年年终报告

2012-12-31 by weejar zhang

2012年最后一天，2B政策非要上班，未见预测世界末日，只当做为新的开端。日志数 491 只是工作日发表，一年大概有240多个工作日，目标是每天学2个以上知识点，每个工作日在此站点记录一篇，看来从建站到今天还是有些日子偷懒了。本站从2010-11-22 起来加入CNZZ.com统计 PV 独立访客 IP 每日平均： 189 146 142 历史最高： 662 (2012-07-05) 601 (2011-01-19) 370 (2012-06-05) 历史累计： 103100 78316 72833 访问分布全国各省份和10几个国家 top 5 地区分布北京广东上海美国江苏 top 5 浏览器 chrome IE8 firefox 360 IE9