Is there any tool to explain how a query executes in SQL Server

Hi Is there any tool which explains how a query executes in SQL Server.

For example,


in the above query, how data is fetched, how data is filtered, when join is executed such kind of things can any tool explain? i heard about query analyzer but its complex is there any simple tool :)

more ▼

asked Aug 10, 2011 at 11:04 PM in Default

avatar image

174 26 27 30

Pick up any tsql book or read any number of thousands of blogs about tuning sql.

Aug 11, 2011 at 06:20 AM mikelanders
(comments are locked)
10|1200 characters needed characters left

4 answers: sort voted first

Display actual execution plan in the toolbar is a good start (or use: SET STATISTICS XML ON )

I also use Set statistics io on; Set statistics time on;

You can also get the execution plans from the cache by the DMV:

 SELECT * FROM sys.[dm_exec_query_stats] AS DEQS
 CROSS APPLY sys.[dm_exec_query_plan]([DEQS].[plan_handle]) AS DEQP
 ORDER BY [DEQS].[last_execution_time]

This will give you a lot of information about the queries executed. You can sort and find slow or resource intense queries by this query. When you find the "worst" queries you can have a look at the execution plan to see whats wrong with it, and whats wrong always depends, but you can start to look for SCANS or KEY lookups, estimated cost, and the size of the arrows (the wider, the more data from each step). But to fully understand you should read the books from @grant fritchey.

more ▼

answered Aug 10, 2011 at 11:06 PM

avatar image

Håkan Winther
16.6k 37 46 58

(comments are locked)
10|1200 characters needed characters left

In sql server management studio, instead of executing the query; hit Ctrl+L and you'll ser the estimated query plan.

more ▼

answered Aug 10, 2011 at 11:07 PM

avatar image

Magnus Ahlkvist
22k 20 41 42

  • actual and estimated may differ, but you should always show estimated before you execute anything to see if you will get any result within a couple of seconds and not a couple of hours

Aug 10, 2011 at 11:21 PM Håkan Winther

any guide to understand the ouput of query analyzer :)

Aug 10, 2011 at 11:31 PM pvsrinivasrao
(comments are locked)
10|1200 characters needed characters left

To start understand the query plans, you can read article Understanding More Complex Query Plans by @Grant Fritchey and even There are also links to his excelent book Dissecting SQL Server Execution Plans.

more ▼

answered Aug 10, 2011 at 11:45 PM

avatar image

Pavel Pawlowski
22.7k 10 15 26

Of course you can also refer the MSDN: Logical and Physical Operators Reference

Aug 11, 2011 at 12:57 AM Pavel Pawlowski
(comments are locked)
10|1200 characters needed characters left

In addition to the other answers, if you want a detailed explanation of each of the showplan operators then the series of article that Simple Talk has here http://www.simple-talk.com/search/default.aspx?search=showplan+operator+of+the+week is a great reference

more ▼

answered Aug 11, 2011 at 12:15 AM

avatar image

Fatherjack ♦♦
43.8k 79 99 118

That series takes a lot of time to get through, but it is well worth reading if you are trying to understand what the plan means.

Aug 11, 2011 at 09:37 AM TimothyAWiseman
(comments are locked)
10|1200 characters needed characters left
Your answer
toggle preview:

Up to 2 attachments (including images) can be used with a maximum of 524.3 kB each and 1.0 MB total.

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

SQL Server Central

Need long-form SQL discussion? SQLserverCentral.com is the place.



asked: Aug 10, 2011 at 11:04 PM

Seen: 1041 times

Last Updated: Aug 10, 2011 at 11:04 PM

Copyright 2017 Redgate Software. Privacy Policy