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Asked: 2026-06-06T19:22:25+00:00

While transforming some data to SQL Azure, I have noted an unexpected behavior. I

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While transforming some data to SQL Azure, I have noted an unexpected behavior.
I did a quick test and this is the result:

I have a single table in the DB with 1M records and the DB size is 230MB, this without the non-clustered index.

I did a simple test by creating a new table with the same schema and just copied the data from one table to another like this:

INSERT INTO [dbo].[lete_new]
           ([str_en]
           ,[str_en_fp])
SELECT [str_en] ,[str_en_fp] FROM [dbo].[lete]

First of all, on me local workstation (SELECT [str_en] ,[str_en_fp] FROM [dbo].[lete]) takes 8 seconds, so on-top of that is the time that it takes to do the insert.
When I ran the insert on my local WS, it took 10 seconds to copy the data to the new table. The big surprise was when I ran the same query on Azure, it took 30 seconds.

I know that this is not exactly a programming question, but still this will impact the program performance an I want to know why is the performance drop?

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1 Answer

  1. Editorial Team

    There quite a few things coming into play here. With this type of operation, the one the is affecting you the most is that the storage system on you local drive is not the same as what SQL Azure runs on top of. Keep in mind that all writes are replicated so that failures can be handled quickly. With this many writes, I suspect that this is where the majority of the difference is seen.

    Also, keep in mind that a SQL Azure instance is shared with other users and it sits on commodity hardware. The performance of a system with 4 cores dedicated to a single user (your desktop) is going to differ from any server that is running with other users (SQL Azure).

    In general you will not be able to equate performance of a single dedicated resource to that of a cloud provider. The benefits come from lower cost ramp up and scale out instead of scaling up.

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