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When you are programming in SQL, you often have the choice of using table variables or temporary tables. This blog considers whether one method is substantially quicker than the other (spoiler alert: not really).
- Are Temporary Tables or Table Variables Quicker in SQL?
- The Example Used for this Speed Comparison
- Speed Comparison - Temporary Tables
- Speed Comparison - Table Variables (this blog)
- Comparison of Results
Posted by Andy Brown on 02 March 2017
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Speed Comparison - Table Variables
The SQL query to generate the table of rows for table variables is nearly identical to the one for using a temporary table:
-- create a new one
DECLARE @AdviceRows TABLE (
ID int,
OwlyAdvice varchar(100)
)
-- the number of rows to generate
DECLARE @max int = 100000
-- loop counter used and string variable
DECLARE @i int = 1
DECLARE @s varchar(100)
-- keep going till we've created enough rows
WHILE @i <=>
BEGIN
-- text to store
SET @s =
CASE
WHEN @i % 3 = 0 THEN 'This too shall pass'
WHEN @i % 3 = 1 THEN 'Look before you leap'
ELSE 'Fortune favours the brave'
END
INSERT INTO @AdviceRows (ID,OwlyAdvice)
VALUES (@i,@s)
SET @i = @i + 1
END
SELECT
a.OwlyAdvice AS Advice,
COUNT(*) AS Frequency
FROM
@AdviceRows AS a
GROUP BY
a.OwlyAdvice
ORDER BY
Frequency ASC
SELECT * FROM @AdviceRows
Now we've seen the two test queries, it's time to compare the results!
- Are Temporary Tables or Table Variables Quicker in SQL?
- The Example Used for this Speed Comparison
- Speed Comparison - Temporary Tables
- Speed Comparison - Table Variables (this blog)
- Comparison of Results