- 浏览: 25814 次
- 性别:
- 来自: 北京
最新评论
1.heap table
IOT
PARTITION TABLE
HEAP TABLE
CLUSTER
2.create table t(
id number,
varchar2(80),
name char2(10)
)
pctfree 20
pctused 40
storage(
initial 180k
next 180k
pctincrease 10
miniextents 3
maxextents 5
)
tablespace users
create global temporary table temp(id number,name char(10));
alter table t pctfree 30 pctused 40 storage(initial 180k next 180k minixtents 3 maxextents 5);
alter table t allocate extent(size 600k datafile '/u01/oradata/lsh/data01.dbf');
alter table t move tablespace user1;
truncate table t // no generation undo log,ddl ,can not truncate the table which have refer.realease space. index are truncate
truncate table t reuse storage;
drop table t
alter table t drop column name cascade constraints checkpoint 1000;
alter table t drop columns continue;
alter table t set unused column name cascade constraints;
alter table t dop unused columns checkpoint 1000
alter table t dop columns continue checkpoint 1000
alter table t rename column name to vname
select dbms_metadata.get_ddl('TABLE','T') from dual;
select * from user_object;
select * from user_tables;
1.HEAP TABLE:
Oracle will place the data where it fits, not in any order by date or transaction
You should think of a heap organized table as a big unordered collection of rows. These
rows will come out in a seemingly random order, and depending on other options being used
(parallel query, different optimizer modes, and so on), they may come out in a different order
with the same query. Do not ever count on the order of rows from a query unless you have an
ORDER BY statement on your query!
2.IOT:
Index organized tables (IOTs) are, quite simply, tables stored in an index structure.
We have to make room for both the table and the index on the primary key of the table when using a heap organized table. With an IOT, the space overhead of the primary key index is removed, as the index is the data and the data is the index.
When you want to enforce co-location of data or you want data to be physically stored in a specific order, the IOT is the structure for you.
• Increased buffer cache efficiency, as any given query needs to have fewer blocks in the
cache
• Decreased buffer cache access, which increases scalability
• Less overall work to retrieve our data, as it is faster
• Less physical I/O per query possibly, as fewer distinct blocks are needed for any given
query and a single physical I/O of the addresses most likely retrieves all of them (not
just one of them, as the heap table implementation does)
Each I/O and each consis-tent get requires an access to the buffer cache, and while it is true that reading data out of the buffer cache is faster than disk, it is also true that the buffer cache gets are not free and not totally cheap. Each will require many latches of the buffer cache, and latches are serialization devices that will inhibit our ability to scale.
3.
发表评论
-
from string get number data using pl/sql or sql
2012-02-16 17:32 849declare @aa varchar(80),--- ... -
SQL
2012-02-15 18:01 6761.select sal salary from emp; ... -
modify ip
2012-02-10 17:45 7491.netconfig 2./etc/sysconfig/n ... -
MULTI dbwr or io slaves
2012-02-10 15:21 841thanks dukope of itpub. ... -
FAQS
2012-02-09 15:59 7061.How can I get the largest amo ... -
HOW TO STUDY ORACLE FROM Yong Huang
2012-01-18 14:48 760Assuming you want to study orac ... -
RMAN
2012-01-14 17:07 6501.components of the rman ... -
INSTANCE and CRASH RECOVERY
2012-01-12 10:12 7101.type of checkpoint full c ... -
STARTUP PFILE=
2011-12-31 14:11 11161.vi initdbs.ora spfile=&quo ... -
MONITOR redo size
2011-12-21 17:48 6121.set autot on stat 2.unsin ... -
What do rollback and commit
2011-12-21 11:21 701When we COMMIT, all that is lef ... -
What is the schema ?
2011-12-20 15:18 555A schema is a collection of dat ... -
MANAGE UNDOTABS
2011-12-19 17:15 6501.manual undo_management=ma ... -
DBA SQL
2011-12-19 15:21 4101.select a.name,b.status from v ... -
SEGMENT EXTENTS ORACLEBLOCK
2011-12-15 16:11 7551.SEGMENT: allocated fo ... -
MANAGE TABLESPACE AND DATAFILES
2011-12-13 15:28 5361. tablespace,segment,extent,bl ... -
ORACLE NET
2011-12-12 09:49 6541.net_service_name: servive ... -
SQLPLUS TIPS
2011-12-09 17:51 8671.SQLPLUS : a tool that execute ... -
ORACLE ENVIRONMENT VARIABLES
2011-12-09 17:15 623ORACLE_HOME ORACLE_SID : or ... -
Exam Test1
2011-12-09 16:18 6071.utl_file_dir: indicate the di ...
相关推荐
最近在数据库中删除了一张表,重新执行python manage.py migrate时出错,提示不存在这张表。通过查找相关的资料,最后找到了相关的解决方法,下面话不多说了,来一起看看详细的介绍吧 二、原因 主要是因为django一般...
emWin 设计用于提供高效且独立于处理器和显示控制器的图形用户界面,用于任何使用图形显示进行 操作的应用。它与单任务和多任务环境、专用操作系统或具有任何商业RTOS 兼容,emWin 的发货 形式为C 语言源代码。...
操作系统:Win7 IDE:PyCharm4.5.3 Django:1.10.1 报错代码:request.session[‘key’] = value 描述:今天第一次使用Django中的session,只要出现”...1.9之前的执行’python manage.py syscdb’命令(baidu的时候
CREATE TABLE [dbo].[admintable] ( [ID] [int] NULL , [username] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL , [password] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL , [firstname] [varchar] ...
some table about note manage
CREATE TABLE BookInfo ( bookid int(4) NOT NULL UNIQUE , bookname varchar(100) , pubname varchar(100) , ...CREATE TABLE manage ( manageid int(4) NOT NULL UNIQUE, Pass char(10) ) ; 自己弄的
servlet_user_managejava servlet_user_manage demo project , Just for Learning Java Servlet采用 grade 依赖管理工具管理项目依赖和构建数据库创建语句users用户表创建CREATE TABLE `users` ( `id` int(11) NOT ...
相对与传统的table, 采用DIV+CSS技术的网页,对于搜索引擎的收录更加友好。 4、样式的调整更加方便。内容和样式的分离,使页面和样式的调整变得更加方便。 二、首页简洁,打开响应速度快。 三、有基本的产品,新闻...
It brings additional functionality to the table, something that is lacking in Kubernetes. This new functionality significantly helps software development teams to bring software development processes...
Table of Contents Chapter 1. Introduction to PowerCLI Chapter 2. Learning Basic PowerCLI Concepts Chapter 3. Working with Objects in PowerShell Chapter 4. Managing vSphere Hosts with PowerCLI Chapter ...
Table of Contents Chapter 1 Getting Started with Ansible and Cloud Management Chapter 2 Using Ansible to manage AWS Elastic Compute CLoud (EC2) Chapter 3 Managing Amazon Web Services with Ansible ...
django.db.utils.OperationalError: (1050, "Table 'xxx' already exists") 要处理这种情况,如果是数据表都已经存在了,在migrate时直接使用 –fake-initial 来处理 python manage.py migrate –fake-initial 如果...
Table of Contents Chapter PART I Database Architecture Chapter 1 Getting Started with the Oracle Architecture Chapter 2 Upgrading to Oracle Database 12c Chapter 3 Planning and Managing Tablespaces ...
Next, the book covers how to create and manage Azure storage accounts, including file, blob, and table storage. Moving on, this book covers creating and managing Azure virtual machines, SQL databases...
Table of Contents Chapter 1: An Introduction to the Windows File System Chapter 2: Understanding Windows File Systems Chapter 3: Permissions, Ownership, and Auditing Chapter 4: Managing File Sharing ...
Table of Contents Chapter 1. Introduction Chapter 2. RPC Mechanisms Chapter 3. The RESTful API Service Chapter 4. Junos PyEZ Chapter 5. Commit Scripts Chapter 6. Op Scripts Chapter 7. Event Scripts ...
Table of Contents Chapter 1 An Introduction to Linux Chapter 2 Working with the Linux Shell Chapter 3 Using the vi Text Editor Chapter 4 Managing Linux Files and Directories Chapter 5 Installing Linux...
Table of Contents Chapter 1. OpenStack Networking Components – an Overview Chapter 2. Installing OpenStack Using RDO Chapter 3. Neutron API Basics Chapter 4. Interfacing with Neutron Chapter 5. ...