SQL Server: How to insert million numbers to table fast?

Yesterday I attended at local community evening where one of the most famous Estonian MVPs – Henn Sarv – spoke about SQL Server queries and performance. During this session we saw very cool demos and in this posting I will introduce you my favorite one – how to insert million numbers to table.

The problem is: how to get one million numbers to table with less time? We can solve this problem using different approaches but not all of them are quick. Let’s go now step by step and see how different approaches perform.

NB! The code samples here are not original ones but written by me as I wrote this posting.

Using WHILE

First idea for many guys is using WHILE. It is robust and primitive approach but it works if you don’t think about better solutions. Solution with WHILE is here.

declare @i as int
set @i = 0

while(@i < 1000000)
begin    
   insert into numbers values(@i)
   set @i += 1
end

When we run this code we have to wait. Well… we have to wait couple of minutes before SQL Server gets done. On my heavily loaded development machine it took 6 minutes to run. Well, maybe we can do something.

Using inline table

As a next thing we may think that inline table that is kept in memory will boost up performance. Okay, let’s try out the following code.

declare @t TABLE (number int)
declare @i as int
set @i = 0

while(@i < 1000000)
begin    
   insert into @t values(@i)
   set @i += 1
end

insert into numbers select * from @t

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