Sunday, January 31, 2010

Teradata warehouse introduction

http://www.info.teradata.com/eDownload.cfm?itemid=062330006&redirectfromfle=y

A single Teradata system can support a maximum of 16,384 vprocs (virtual processor). The maximum number of vprocs per node can be as high as 128, but is typically between 6 and 12

The AMP is the heart of the Teradata Database. The AMP is a vproc that controls the
management of the Teradata Database and the disk subsystem, with each AMP being assigned to a vdisk.

Vprocs provide the parallel environment that enables the Teradata Database to run on SMP and MPP systems. Vprocs come in two types:
• Access Module Processors (AMPs) ( manage a portion of disk
• Parsing Engines (PEs). (decompose sql and return answer (dispatcher; parser;opti;)

Query are scattered to BYNET linked CLIQUE (Fully inter-linked nodes and arrays), AMP get instruction and return data (3 steps: LOCK for serialization and consistency;

************************************************
Teradata Training Program
Total Training Duration: 3 PD ( 24 Hour)

- Basics (2Hours)
- Architecture (3 hours)
- SQL (4 Hours)
- ETL Utilities (3 Hours)
- Case Study (12 Hours)


Basics:

- Basic Architecture of Teradata
- The uniqueness of Teradata SQL and to know different functions available in Teradata.
- Different Utilities (FastLoad, FastExport, MultiLoad, Tpump,Teradata Warehouse Miner) in Teradata.
- How Teradata is ideal for Datawarehouse application.


Architecture:

Hardware components:
The hardware that supports Teradata RDBMS software is based on off the-shelf Symmetric Multiprocessing (SMP) technology. Hardware Components are:

• SMP Systems
• MPP Systems
• BYNET
• VPROCS
- Parsing Engine (PE )
- Access Module Processor (AMP)

Software Architecture:
• Parallel Database Extensions (PDE)
• Teradata File System
• Trusted Parallel Applications (TPA )
• Virtual Processors - PE and AMP
• PERM Space
• SPOOL Space



SQL:
- Teradata DDL(create, Drop, Alter)
- Teradata DML(Select, Insert,Update, Delete),
- Teradata DCL(Grant, Revoke).
- Teradata extensions to SQL like HELP, SHOW, EXPLAIN, CREATE MACRO, REPLACE MACRO.
- Primary index / Secondary Index
- SET operators(UNION,INTERSECT,EXCEPT, MINUS)


ETL Utilities:

Fload: This utility provides us with facility for loading new tables onto Teradata database

Fast export: This utility exports a large volume of data from Teradata to a host file or user-written application.

Multiload: This utility supports INSERT,UPDATE, DELETE and UPSERTS typically with batch inputs from a host file.

TPump: This utility allows the real time update from transactional systems into warehouse.


Case Study:

Administration:
- To create a user , database and understand the hierarchy of user and database.
- To create a table with columns having datatype integer, char, decimal, date and having one primary index.
- To drop a table in a database or a user.

SQL:
- To use SELECT statement with ORDERBY and GROUPBY clause.
- To use inner join, LEFT Outer Join, Right Outer Join and Full Outer Join on two tables.
- To use CASE, COALESCE, NULLIF, IFNULL
- To use set operators(UNION,INTERSECT,EXCEPT)

Fast Load:
- To create a empty table in TeraData and prepare a flat file containing data. Prepare a script for loading the data from flat file into the empty table.

Fast Export:

- To use the FastExport to create an export file that contains one record for each transaction . Columns from two different tables has to be joined inorder to create the export file.

MultiLoad:
- To use Multiload to delete rows from your three tables. An input file will be created which will contain a control letter(A-Accounts, C-customer, T-trans) followed by a primary index value for the appropriate table

TPUMP:
- Use FastExport to export the records into a flat file. Prepare Tpump script which performs UPSERT operation on another table.Validate your results.

Labels:

Wednesday, January 27, 2010

New smokers

Just a thought, from what channel new smokers started to smoke?
(both manufacturer and government will like to know this!)

Sunday, January 24, 2010

SAP最基本概念:

Transaction code(不同操作功能)
如:AL07 EarlyWatch ReportAL08 Users Logged On

一个SAP transaction是在R/3, CRM, BW或其它SAP系统中的任何逻辑处理。简单来说,一个transaction是一个自包含的单元,一个有起点和终点的步骤集合,最后会有某种输出或是对底层的SAP数据库进行了更新。
SAP transactions的例子有:
创建一个新的客户, 生成一个现有客户表单,处理订单,执行一个程序。”
Tables:

T000: contains defined clients
USR02: store user ID/pass

TRBAT表的列名:
TRKORR
Function
RETCODE
TIMESTMP
TRKORR


The table columns have the following meaning:
TRKORR
Contains the names of the change requests
FUNCTION
Contains a key for the requested action. Possible values are:
A

Thursday, January 21, 2010

Oracle Professional Programming读书微笔记

exclusive lock, shared lock in oracle
Oracle解决多用户的拥塞Contention,很巧妙:用SCN,每个交易有唯一一个递增的SCN,历史SCN修改的表数据在rollback buffer中,如果本交易读写某列时发现该列附属的SCN比自己新,则去找rollback buffer

Saturday, January 16, 2010

国外垄断公用事业单位也是高薪。。

Centrica是英国煤气等垄断国企的控股总公司,FTSE30强,偶然一看,其工资水平了不得,系统维护(电脑)起薪4万4千镑,合人民币50-60万。比普通的电脑维护足足高了一倍不止。。。

而且其网站很怪异,就一个文件,从首页到具体招聘信息,都是用index.asp从数据库调,这实在是让我责怪自己见不多识不广,不知道为何要这么设计。

http://www.centrica.com/index.asp?pageid=366



Desktop Specialist [CEN1661]
Job details

Centrica
• Staines
Sound ByteBase salary up to £44K (experience related) + Bonus + Benefits

Head of IS Architecture [CE1518]
Job details

Centrica Energy
• Windsor
Sound BytePackage c. £150K - £180+

Sunday, January 10, 2010

PWC, E&Y, HP interview 面试要点:

通杀最佳问题:你在这里工作多久,最喜欢哪一点(NLP心理学技巧,让对方有个愉快的心情,因为讲述自己熟悉的东西总是愉快的)
Best questions to ask: how long have you been with, what do you like most about working here

PWC:global core competencies;强调企业对communite的贡献及责任,拥有最多的FTSE客户
PWC六块业务:Assurance(Audit)鉴证,Consulting(战略管理人事咨询)Actuarie(保险,年金精算),Tax, Legal,Advisory(收购,亏损)
PWC希望招人的素质:Curiosity; Flexible(quick-learning and adaptable); Great communication; team working; commercial awareness

问题:9个球,一个重量不同,3次称出

项目实施方法妙语“ask the patient where it hurts before open them up and look around for injuries”
HP惠普:公司定位 technical leader, want to be in top3 in everything it does.注重客户,专注于所在市场,定位是只做前3名。人性化
需要的soft skills: client-focusing, team working, problem-solving, self-motivated, communication,hard-working, reliable

E&Y:team working