[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
?
Solved

logical vs physical reads

Posted on 2006-11-16
6
Medium Priority
?
951 Views
Last Modified: 2008-03-17
what is the difference between logical reads and physical reads?
0
Comment
Question by:yanci1179
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
6 Comments
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 1200 total points
ID: 17959845
physical reads means the data has been read from disk into memory
logical reads means the the data was already in memory

1 logical reads means 1 page of data, ie 8KB
0
 

Author Comment

by:yanci1179
ID: 17959911
i read that in books online....but it didn't really mean much.  Ideally which one should be lower?
0
 
LVL 32

Assisted Solution

by:Brendt Hess
Brendt Hess earned 800 total points
ID: 17959980
In a perfect world, physical reads would be equal to the number of data blocks in your database, and all other reads would be logical.  So, by preference logical reads should be the higher of the two.
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 17960495
perfectly, the physical reads should be 0. also, logical reads as low as possible.
0
 

Author Comment

by:yanci1179
ID: 17960572
let me see if I understand this logical data read from what is already in cache.  if it's not there then it has to read the physical tables and retrieve the data?
0
 
LVL 32

Expert Comment

by:Brendt Hess
ID: 17962141
Absolutely correct.
0

Featured Post

Veeam Disaster Recovery in Microsoft Azure

Veeam PN for Microsoft Azure is a FREE solution designed to simplify and automate the setup of a DR site in Microsoft Azure using lightweight software-defined networking. It reduces the complexity of VPN deployments and is designed for businesses of ALL sizes.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A Stored Procedure in Microsoft SQL Server is a powerful feature that it can be used to execute the Data Manipulation Language (DML) or Data Definition Language (DDL). Depending on business requirements, a single Stored Procedure can return differe…
An alternative to the "For XML" way of pivoting and concatenating result sets into strings, and an easy introduction to "common table expressions" (CTEs). Being someone who is always looking for alternatives to "work your data", I came across this …
Via a live example combined with referencing Books Online, show some of the information that can be extracted from the Catalog Views in SQL Server.
Via a live example, show how to extract insert data into a SQL Server database table using the Import/Export option and Bulk Insert.

656 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question