作者: Maclean Liu, post on November 2nd, 2010 昨天晚上去客户现场配合一个导入导出作业；这是一套Solaris 10上的10.2.0.1系统，导出采用expdp数据泵工具，需要导出的数据源是一张大小在120G左右的单表，该表存放了最近一年的数据，实际导出时只需要最近三个月的数据，所以使用了QUERY参数,并指定了并行度为2。 该导出作业之前未经测试过，语句也是临时写的，实际执行导出工作时发现在评估阶段(estimate phase)耗费了大约十多分钟的时间，estimate默认使用blocks模式，即通过计算对象段占用的数据库块来预估dumpfile的大小；此外还有statistics模式通过对象的统计信息来推算导出文件的大小:
The block method of estimate is the least accurate. We investigate how many blocks were allocated for the storage segments for the tables specified. If the table had been recently analyzed, the estimate=statistics would be the most accurate. So remember, it is important to generate statistics before calculating the estimate using . . . → Read More: No way to disable datapump estimate？
作者: Maclean Liu, post on November 2nd, 2010 这是一个十分简单的单表导出作业，表上大约有200万条数据；但实际exp导出时dump文件每秒增长不足1MB，速度十分缓慢。
SQL> show user; USER is “SH” SQL> select count(*) from orders; COUNT(*) ———- 2319232 SQL> select bytes/1024/1024 from dba_segments where owner=’SH’ and segment_name=’ORDERS’; BYTES/1024/1024 ————— 261 /*该表大小为261MB*/ /*这里我们使用直接路径导出*/ [maclean@rh2 ~]$ exp sh/sh file=/s01/orders.dmp direct=y tables=orders Export: Release 11.2.0.1.0 – Production on Wed Aug 18 21:52:56 2010 Copyright (c) 1982, 2009, Oracle and/or its affiliates. . . . → Read More: Poor Data Export Performance(revised)
作者: Maclean Liu, post on June 6th, 2010
Recently i find many session are waiting for Event <cursor pin s on x> in my customer’s AIX 10.2.0.4 instance, it’s a new event in the 10gr2,after mutex take place of latch .
When a session is going to parse or reparse one cursor, need to pin X this cursor first. Then the others who . . . → Read More: single-task message and cursor pin S on X
作者: Maclean Liu, post on October 2nd, 2009
作者: Maclean Liu, post on September 23rd, 2009 Applies to:
Oracle Server – Enterprise Edition – Version: 9.0.1.0 to 11.2.0.1.0 – Release: 9.0.1 to 11.2 Oracle Server – Enterprise Edition – Version: 9.0.1.0 to 11.2.0.1.0 [Release: 9.0.1 to 11.2] Information in this document applies to any platform.
Goal
A clear, step by step, method to diagnose an ORA-1555 issue using either
UNDO_MANAGEMENT = AUTO … Automatic Undo . . . → Read More: TROUBLESHOOTING GUIDE (TSG) – ORA-1555
作者: Maclean Liu, post on August 12th, 2009 Applies to:
Oracle Server – Enterprise Edition – Version: 8.0.3.0 to 11.1.0.7 – Release: 8.0.3 to 11.1 Information in this document applies to any platform.
Purpose About this Document
This document mainly discusses few generic concepts on sysdba authentication and corresponding troubleshooting steps , which will be helpful in resolving the error ORA-1031 insufficient privileges, . . . → Read More: Troubleshooting ORA-1031 Insufficient Privilege
作者: Maclean Liu, post on April 29th, 2009 Applies to:
Oracle Server – Enterprise Edition – Version: 9.2.0.1 and later [Release: 9.2 and later ] JDBC – Version: 9.2.0.1 and later [Release: 9.2 and later] Information in this document applies to any platform. ***Checked for relevance on 20-Apr-2010***
Symptoms
fact: JDBC fact: Genesys symptom: Installing 3rd party product Genesys symptom: Installation fails symptom: java.sql.SQLException: symptom: ORA-17401: Protocol . . . → Read More: Installing 3rd Party Product Genesys Fails with java.sql.SQLException
作者: Maclean Liu, post on June 8th, 2008 @Checked for relevance on 30-MAY-2007 Problem Description ——————- You start up the database and receive the following error message: SQL> startup ORACLE instance started. Total System Global Area 252478536 bytes Fixed Size 279624 bytes Variable Size 167772160 bytes Database Buffers 83886080 bytes Redo Buffers 540672 bytes Database mounted. ORA-01092: ORACLE instance terminated. Disconnection forced No . . . → Read More: ORA-1092 During Startup Using AUM (Automatic Undo Management)
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