By Igor Borisenko

2014-02-21 08:40:50 8 Comments

I have a table on SQL Asure server with no indexes except clustered. And I insert into this table small amount of data just about 1000 rows and it takes more than 4 minutes. Although, when I do it with SSIS it takes just a second. This is the query:

INSERT INTO DatabaseName.dbo.tmpOurClients
(KodClient,Name ,ShortName,INN,Boss,contact,Email,Adres,Tel,City_ID,DateLop)
SELECT KodClient,Name ,ShortName,INN,Boss,contact,Email,Adres,Tel,City_ID,DateLop
FROM dbo.OurClients

That is how I created the Linked Server:

EXEC sp_addlinkedserver

EXEC sp_addlinkedsrvlogin
@rmtuser='[email protected]',

EXEC sp_serveroption 'Azure', 'Collation Compatible', true;

I've already checked this topic Linked server to SQL Azure very slow but none of suggestions helped me.

Version of local SQL-Server: Microsoft SQL Server 2008 R2 (SP2) - 10.50.4000.0 (X64) Jun 28 2012 08:36:30 Copyright (c) Microsoft Corporation Enterprise Edition (64-bit) on Windows NT 6.1 (Build 7601: Service Pack 1) (Hypervisor)

So, what can be the problem?


@Paul White 2014-02-21 12:21:08

I insert into this table small amount of data just about 1000 rows and it takes more than 4 minutes

Remote data modifications through a linked server use the sp_cursor model. The effect is similar to issuing 1000 separate single inserts (one for each row). If a round trip takes 250ms, 1000 such trips will take 4 minutes and 10 seconds. Using a bulk loading method such as bcp or SSIS will generally be more efficient (unless the number of rows to be inserted is tiny).

Another alternative for ad-hoc needs is to build a string containing a single INSERT statement with multiple rows in the VALUES clause. The statement is then used with EXECUTE AT, for example:

-- Note local-to-azure table name used, not four-part syntax
DECLARE @sql varchar(max) = 'INSERT dbo.Test VALUES ';

-- Build a list of 1000 numbers to insert    
SELECT @sql += '(' + CONVERT(varchar(11), n) + '),'
FROM dbo.Numbers AS N

-- Remove trailing comma
SET @sql = LEFT(@sql, LEN(@sql) - 1);

-- For debugging
PRINT @sql;

-- Execute the finished statement at the remote server;

The constructed insert statement executes at the Azure database, so a local name is used for the table (note: building a dynamic insert statement using a four-part target name buys you nothing).

Note that EXECUTE ... AT requires RPC and RPC OUT enabled in the linked server options.

The VALUES clause for a plan INSERT statement is limited to 1000 elements. There are ways around that (a VALUES clause in a CTE does not have that restriction). You could also choose to build 1000-row batches or build single-row insert statements, but if the there is that much data on a regular basis, you would probably be better off using one of the bulk loading methods instead.

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