이수안 데이터 연구실

By Craig Utley

Introduction

Creating a Star Schema Database is one of the most important, and sometimes the final, step in creating a data warehouse. Given how important this process is to our data warehouse, it is important to understand how me move from a standard, on-line transaction processing (OLTP) system to a final star schema (which here, we will call an OLAP system).

This paper attempts to address some of the issues that have no doubt kept you awake at night. As you stared at the ceiling, wondering how to build a data warehouse, questions began swirling in your mind:

What is a Data Warehouse? What is a Data Mart?
What is a Star Chema Database?
Why do I want/need a Star Schema Database?
The Star Schema looks very denomalized Won't I get in trouble for that?
Should I repaint the ceiling?

These are certainly burning questions. This paper will attempt to answer these questions, and show you how to build a star schema database to support decision support within your organization.

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The Value of Merge-Join and Hash-Join in SQL Server

이수안 데이터 연구실

Database/MSSQL

2007/06/22 09:30, 글쓴이

Goetz Graefe
Microsoft, Redmond, WA 98052-6399
GoetzG@Microsoft.com

Abstract
Microsoft SQL Server was successful for many years for transaction processing and decision support workloads with neither merge join nor hash join, relying entirely on nested loops and index nested loops join. How much difference do additional join algorithms really make, and how much system performance do they actually add? In a pure OLTP workload that requires only record-to-record navigation, intuition agrees that index nested loops join is sufficient. For a DSS workload, however, the question is much more complex. To answer this question, we have analyzed TPC-D query performance using an internal build of SQL Server with merge-join and hash-join enabled and disabled. It shows that merge join and hash join are both required to achieve the best performance for decision support workloads.

The Value of Merge-Join and Hash-Join in SQL Server.pdf