Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Tune SQL – WHERE by 2 fileds in one Table – 2 indexes or 1 index with 2 fields?

Posted on 2014-10-21
3
Medium Priority
?
136 Views
Last Modified: 2014-10-21
Dear experts,

I have the task to tune one SQL 2008R2 DB. I have follow t-SQL

Select Table1.F1,Table1.F2, Table1.F3, Table1.F4,OtherTable.F10,OtherTable.F11 .... ,OtherTable.F12 FROM ….  JOIN ...  WHERE Table1.F1 <getdate() AND Table1.F2=2 and …

My question is focus on Table1 where I search by 2 criteria. I wonder I should create 2 separated indexes on every filed, or one index with 2 fields. I know the best way it to measure this via Execution plan, but I think this is a common situation with common recommended solution. I’m focused on speed; My Table1 will have less than 10 000 records, will be relative rarely write, but will be read from this SP all the time.

And I have the same question, but for other table which will have millions of records and will be heavy read and write as well. Then what is the standard solution?
0
Comment
Question by:dvplayltd
  • 2
3 Comments
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 2000 total points
ID: 40393843
1 index with the 2 fields would be the general rule, and the field with the best cardinality first.
means if you have the 2 fields like gender + firstname (just an example), gender has 2-3 distinct values, while firstname has lots of different values, so you would create the filter on firstname + gender and not gender + firstname

note that such a index (firstname + gender) will also be able to help queries that will only search by firstname
note that such a index (firstname + gender) will not be able to help queries that will only search by gender
0
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 40393847
in your concrete scenario, there come several possible solution paths:
* clustered index on F2 + F1
* partition on F2 + index on F1
* partition on F1 + index on F2
0
 

Author Closing Comment

by:dvplayltd
ID: 40393866
10x, i got what you mean. I'll put first field of the index Date /may have many different values/, then on second position Type which have 4 possible values only.
0

Featured Post

NFR key for Veeam Agent for Linux

Veeam is happy to provide a free NFR license for one year.  It allows for the non‑production use and valid for five workstations and two servers. Veeam Agent for Linux is a simple backup tool for your Linux installations, both on‑premises and in the public cloud.

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…
What if you have to shut down the entire Citrix infrastructure for hardware maintenance, software upgrades or "the unknown"? I developed this plan for "the unknown" and hope that it helps you as well. This article explains how to properly shut down …
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…
Via a live example, show how to extract insert data into a SQL Server database table using the Import/Export option and Bulk Insert.

916 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