Solved

SQL Distinct List for fields in very large tables

Posted on 2014-11-02
4
152 Views
Last Modified: 2014-11-03
Hi

I need to create a distinct list of values for columns in tables that are between 5 and 10 million records.
These lists can be up to 200,000 records long. At the moment I am creating them while my app runs and
it takes a long time. How do I get around this? Should I create views or tables that have a distinct list?
0
Comment
Question by:murbro
4 Comments
 
LVL 48

Accepted Solution

by:
PortletPaul earned 250 total points
ID: 40418824
There is no detail information to work with, so a generic answer would be:

Views will probably be faster than what you do now; Tables would be faster than views.

Indexes on the source table will have a big influence on performance.
0
 
LVL 10

Expert Comment

by:HuaMinChen
ID: 40418866
Hi,
1. put "distinct" to the statement
2. You can then select the records into other table, on which there is table constraint that is ensuring uniqueness of all records.
0
 
LVL 9

Assisted Solution

by:Valliappan AN
Valliappan AN earned 250 total points
ID: 40418920
You can use (NOLOCK) attribute to your select query something like this, to avoid locking of all those records while fetching, which will dramatically give good performance. Something like this:

Select DISTINCT field1, field2,...,fieldn FROM [yourtable] (NOLOCK)
JOIN [anothertable] (NOLOCK) ON <join condition>
 
HTH.
0
 

Author Closing Comment

by:murbro
ID: 40419367
Thanks
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

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

Let's review the features of new SQL Server 2012 (Denali CTP3). It listed as below: PERCENT_RANK(): PERCENT_RANK() function will returns the percentage value of rank of the values among its group. PERCENT_RANK() function value always in be…
Why is this different from all of the other step by step guides?  Because I make a living as a DBA and not as a writer and I lived through this experience. Defining the name: When I talk to people they say different names on this subject stuff l…
Familiarize people with the process of utilizing SQL Server functions from within Microsoft Access. Microsoft Access is a very powerful client/server development tool. One of the SQL Server objects that you can interact with from within Microsoft Ac…
Using examples as well as descriptions, and references to Books Online, show the documentation available for date manipulation functions and by using a select few of these functions, show how date based data can be manipulated with these functions.

777 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