• Home
  • SQL Server
    • Articles
    • T-SQL Puzzles
    • Output Puzzles
    • Interview Questions
    • Performance Tuning
    • SQL SERVER On Linux
    • Resources
  • SSRS
    • SSRS Articles
    • Interview Questions
  • SSAS
    • SSAS Articles
    • DAX
  • SQL Puzzles
  • Interview Questions
    • SQL Interview Questions
    • Data Interview Questions
  • Python Interview Puzzles
  • New Features(SQL SERVER)
    • SQL SERVER 2017
    • SQL SERVER 2016
    • SQL SERVER On Linux
  • Social
    • Expert Exchange
      • Top Expert in SQL
      • Yearly Award
      • Certifications
      • Achievement List
      • Top Expert of the Week
    • HackerRank (SQL)
    • StackOverflow
    • About Me
      • Contact Me
      • Blog Rules

Improving my SQL BI Skills

Improving my SQL BI Skills

Tag Archives: Yet Another Temp Tables Vs Table Variables Article

Which one is better | Temp Table or Table Variable?

12 Friday Jun 2015

Posted by Pawan Kumar Khowal in SQL Performance Tuning

≈ 1 Comment

Tags

26 performance tuning questions and solutions, difference between temp table and table variable in sql server 2008, difference table variable and temp table, Differences between SQL Server temporary tables and table variable, How to tune SQL queries, Interview questions for SQL Server Performance Tuning, Looking for SQL Optimization Interview Questions, performance sql server, Performance tips for faster SQL queries, Performance Tuning, Performance Tuning for SQL Server, Query Optimization, Query Performance Tuning, SQL Complex Queries, SQL Optimization Interview Questions, sql performance, sql performance and tuning, sql performance explained pdf, sql performance tips, SQL Performance Tuning, sql performance tuning and optimization, sql performance tuning interview questions, sql performance tuning tips, SQL Query Optimizer, SQL Query Tuning or Query Optimization, SQL SERVER – Difference TempTable and Table Variable, SQL SERVER Interview questions, SQL server optimization interview questions and answers, sql server performance query, sql server performance slow, SQL Server Performance Tuning, SQL Server Performance Tuning Tips, SQL SERVER Tips, SQL Tuning Overview, table variable statistics, Table Variable V/S Temporary Table, table variable vs temp table, table variable vs temp table in sql server, table variable vs temp table in sql server 2008, table variable vs temp table in sql server performance, temp table and table variable, temp table and table variable difference, temp table and table variable performance, Temporary Tables vs. Table Variables and Their Effect on SQL performance, Tips for SQL Database Tuning and Performance, Top 10 performance tuning tips for relational databases, What's the difference between a temp table and table variable, Yet Another Temp Tables Vs Table Variables Article


Which one is better | Temp Table or Table Variable?

Download PDF – Which one is better | Temp Table or Table Variable?

Whether to use temp tables or table variables is an old interesting question since they were first introduced. In this post we will touch-base the differences between the table variable and Temp Tables.

Let’s check out the differences below then we will see which is better for performance.

Detail Temp Tables Table Variables
Storage Location Stored in TempDB Stored in TempDB
Indexes Yes. Temp table allows both clustered and non-clustered indexes 1 PK/UK Only
Truncate Table Yes No
Alter Table Yes No
SELECT INTO Yes No
Types Yes – Local and Global No
Transaction participation Yes No
Log file writing Yes Yes
Insert with Exec Yes Yes
Statistics Yes No(1 Row always)
Parallelism participation Yes No
Recompiles Yes No

Temp tables are like normal SQL tables that are defined and stored in TempDB. The only difference between Temp table and a physical table is that temp table doesn’t allow foreign keys.

You can view the temp tables currently defined via SSMS by going to TempDB and Expanding Temp Tables.

TempTables

As per my experience temp tables are better than table variables. The problem with the table variables is that query optimizer will generate bad/unpredictable query plans as they don’t have statistics on them.
If you check the estimated number of rows then it will always be 1.


DECLARE @tab AS TABLE ( ID INT )

INSERT INTO @tab
SELECT TOP 100 [CustomerID] FROM [dbo].[CustomerInfo]

SELECT ID FROM @tab

Output see below image
-----------

TableVariables

As a general rule of thumb across many SQL SERVER communities is that if you have 1000 rows or less then go for table variable otherwise go for temp table.
Well we can influence the query optimizer. One of the ways is given below-


DECLARE @x AS INT = 100

DECLARE @tab AS TABLE ( ID INT )
INSERT INTO @tab
SELECT TOP (@x) [CustomerID] FROM [dbo].[CustomerInfo]

Output
-----------

Influenced Table Variable


Table variables do not qualifying for parallelism that’s why they are better suited for small amounts of data.

Table Variables can write to the disk if threshold goes over a certain number of records.

Table variables do write to the log file and they can have non clustered indexes if associated with a ‘NONCLUSTERED UNIQUE’ or ‘NONCLUSTERED PRIMARY KEY’ constraint.

Share this

  • LinkedIn
  • Facebook
  • Twitter
  • WhatsApp
  • Email

Blog Stats

  • 1,097,257 hits

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 1,131 other subscribers

Pawan Khowal

502 SQL Puzzles with answers

Achievement - 500 PuzzlesJuly 18, 2018
The big day is here. Finally presented 500+ puzzles for SQL community.

200 SQL Server Puzzle with Answers

The Big DayAugust 19, 2016
The big day is here. Completed 200 SQL Puzzles today

Archives

June 2023
M T W T F S S
 1234
567891011
12131415161718
19202122232425
2627282930  
« Oct    

Top Articles

  • pawankkmr.wordpress.com/2…
  • pawankkmr.wordpress.com/2…
  • pawankkmr.wordpress.com/2…
  • pawankkmr.wordpress.com/2…
  • pawankkmr.wordpress.com/2…

Archives

  • October 2020 (29)
  • September 2018 (2)
  • August 2018 (6)
  • July 2018 (25)
  • June 2018 (22)
  • May 2018 (24)
  • April 2018 (33)
  • March 2018 (35)
  • February 2018 (53)
  • January 2018 (48)
  • December 2017 (32)
  • November 2017 (2)
  • October 2017 (20)
  • August 2017 (8)
  • June 2017 (2)
  • March 2017 (1)
  • February 2017 (18)
  • January 2017 (2)
  • December 2016 (5)
  • November 2016 (23)
  • October 2016 (2)
  • September 2016 (14)
  • August 2016 (6)
  • July 2016 (22)
  • June 2016 (27)
  • May 2016 (15)
  • April 2016 (7)
  • March 2016 (5)
  • February 2016 (7)
  • December 2015 (4)
  • October 2015 (23)
  • September 2015 (31)
  • August 2015 (14)
  • July 2015 (16)
  • June 2015 (29)
  • May 2015 (25)
  • April 2015 (44)
  • March 2015 (47)
  • November 2012 (1)
  • July 2012 (8)
  • September 2010 (26)
  • August 2010 (125)
  • July 2010 (2)

Article Categories

  • Analysis Services (6)
    • DAX (6)
  • Data (2)
    • Data warehousing (2)
  • Integration Services (2)
  • Magazines (3)
  • Python (29)
  • Reporting Services (4)
  • SQL SERVER (820)
    • Download SQL Interview Q's (212)
    • SQL Concepts (323)
    • SQL Performance Tuning (155)
    • SQL Puzzles (331)
    • SQL SERVER 2017 Linux (6)
    • SQL Server Interview Questions (308)
    • SQL SERVER Puzzles (332)
    • T SQL Puzzles (547)
    • Tricky SQL Queries (439)
  • UI (30)
    • ASP.NET (5)
    • C# (13)
    • CSS (9)
    • OOPS (3)
  • Uncategorized (5)

Recent Posts

  • Python | The Print and Divide Puzzle October 30, 2020
  • Python | Count consecutive 1’s from a list of 0’s and 1’s October 30, 2020
  • Python | How to convert a number into a list of its digits October 26, 2020
  • Python | Validate an IP Address-IPV6(Internet Protocol version 6) October 26, 2020
  • Python | Print the first non-recurring element in a list October 26, 2020
  • Python | Print the most recurring element in a list October 26, 2020
  • Python | Find the cumulative sum of elements in a list October 26, 2020
  • Python | Check a character is present in a string or not October 26, 2020
  • Python | Check whether a string is palindrome or not October 26, 2020
  • Python | Find the missing number in the array of Ints October 26, 2020
  • Python | How would you delete duplicates in a list October 26, 2020
  • Python | Check whether an array is Monotonic or not October 26, 2020
  • Python | Check whether a number is prime or not October 26, 2020
  • Python | Print list of prime numbers up to a number October 26, 2020
  • Python | Print elements from odd positions in a list October 26, 2020
  • Python | Print positions of a string present in another string October 26, 2020
  • Python | How to sort an array in ascending order October 26, 2020
  • Python | How to reverse an array October 26, 2020
  • Python | Find un-common words from two strings October 26, 2020
  • Python | How to convert a string to a list October 26, 2020
  • Python | Find unique words from a string October 26, 2020
  • Python | Calculate average word length from a string October 26, 2020
  • Python | Find common words from two strings October 26, 2020
  • Python | Find the number of times a substring present in a string October 26, 2020
  • Python | Find maximum value from a list October 26, 2020
  • Python | How to find GCF of two numbers October 26, 2020
  • Python | How to find LCM of two numbers October 26, 2020
  • Python | How to convert a list to a string October 26, 2020
  • Python | Replace NONE by its previous NON None value October 26, 2020
  • Microsoft SQL Server 2019 | Features added to SQL Server on Linux September 26, 2018

Create a website or blog at WordPress.com

  • Follow Following
    • Improving my SQL BI Skills
    • Join 231 other followers
    • Already have a WordPress.com account? Log in now.
    • Improving my SQL BI Skills
    • Customize
    • Follow Following
    • Sign up
    • Log in
    • Report this content
    • View site in Reader
    • Manage subscriptions
    • Collapse this bar
 

Loading Comments...
 

You must be logged in to post a comment.