Solved

Comparing SQL queries to determine work required

Posted on 2016-09-05
4
28 Views
Last Modified: 2016-10-23
Hi,

I am trying to compare different queries queries in SQL server to see how much work it takes to process. So in other words the effort to get the results. So is there some sort of metric I can look at. I am guessing something I can compare in the execution plans.

Thanks,

Ward
0
Comment
Question by:whorsfall
[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
4 Comments
 
LVL 50

Accepted Solution

by:
Vitor Montalvão earned 250 total points
ID: 41784908
You can turn on SET STATISTICS before running each query and then compare the results.
0
 
LVL 34

Assisted Solution

by:ste5an
ste5an earned 250 total points
ID: 41784921
1) Use the actual execution plan. Thus execute both queries in the same window. You can also add a SET STATISTICS IO ON to get thre scans and reads in the message pane, And an SET STATISTICS TIME ON for the exact computation time.
2) Use sys.dm_exec_query_stats. Here you need to tag your queries. E.g. start them with --COMPAREME. Then you can compare the results:

SELECT RANK() OVER ( ORDER BY total_logical_reads + total_logical_writes DESC, sql_handle, statement_start_offset ) AS row_no ,
        creation_time ,
        last_execution_time ,
        total_worker_time / 1000 AS total_worker_time ,
        total_logical_reads ,
        total_logical_writes ,
        execution_count ,
        total_logical_reads + total_logical_writes AS total_logical ,
        CASE WHEN sql_handle IS NULL THEN ' '
             ELSE ( SUBSTRING(st.text, ( qs.statement_start_offset + 2 ) / 2,
                              ( CASE WHEN qs.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX), st.text)) * 2
                                     ELSE qs.statement_end_offset
                                END - qs.statement_start_offset ) / 2) )
        END AS query_text ,
        st.text AS sql_text ,
        DB_NAME(st.dbid) AS database_name ,
        st.objectid AS object_id ,
        qp.query_plan ,
        cp.cacheobjtype ,
        cp.objtype ,
        qs.plan_handle
FROM    sys.dm_exec_query_stats qs
        INNER JOIN sys.dm_exec_cached_plans cp ON cp.plan_handle = qs.plan_handle
        CROSS APPLY sys.dm_exec_sql_text(sql_handle) st
        CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
WHERE   st.text LIKE '--COMPAREME%'
ORDER BY total_logical DESC;

Open in new window


This approach takes a look at the entire history of queries. So you may need to clear the plan cache before testing. This can have an effect in production, cause recompiles are enforced.
0
 
LVL 50

Expert Comment

by:Vitor Montalvão
ID: 41805972
whorsfall, it's your question answered?
0

Featured Post

Optimizing Cloud Backup for Low Bandwidth

With cloud storage prices going down a growing number of SMBs start to use it for backup storage. Unfortunately, business data volume rarely fits the average Internet speed. This article provides an overview of main Internet speed challenges and reveals backup best practices.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
SQL Percentage Formula 7 33
Question about Common Table Expressions 3 45
I have an unknown large SQL database I want to get rid of 10 47
how to use ROW_NUMBER() correctly 8 44
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…
Ever needed a SQL 2008 Database replicated/mirrored/log shipped on another server but you can't take the downtime inflicted by initial snapshot or disconnect while T-logs are restored or mirror applied? You can use SQL Server Initialize from Backup…
Via a live example, show how to extract information from SQL Server on Database, Connection and Server properties
Viewers will learn how to use the UPDATE and DELETE statements to change or remove existing data from their tables. Make a table: Update a specific column given a specific row using the UPDATE statement: Remove a set of values using the DELETE s…

752 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