From time to time, we come across the need to transfer data from one SQL Server instance to another, we have several options to choose from and with this blog post, we will compare three common methods: backup and restore, Bulk Copy Program (BCP) Generated Import script and the Export & Import wizard.
Backup and Restore
The Backup and Restore option is the simplest and most reliable method of transferring data between SQL instances. It involves creating a full or differential backup of the source database and restoring it on the destination server.
The advantages of this method are:
- We restore all the database objects (including tables, views, stored procedures), settings and permissions with a single action.
The disadvantages of this method are:
- It requires sufficient disk space on both source and destination servers to store the backup files.
- It may take a long time to complete if the database is large or has a lot of transaction log activity.
- It may cause downtime on the source server if you need to take a full backup or switch to simple recovery model.
- It may not be compatible with different versions or editions of SQL Server.
Best fit use case:
- I use this method whenever I need to copy data from more than a few single tables.
- I use this method whenever I need to ask a “None DBA client” to send me a copy of his dataset.
Bulk Copy Program (BCP)
BCP is a command-line tool that allows you to bulk export or import data from one SQL instance to another. This method is fast and efficient for transferring large amounts of data.
The advantages of this method are:
- Using this method, the exported file format contains both the data and data structure.
- The exported file is quite small and easy to transfer.
- This method is not sensitive to SQL Server version or editions.
The disadvantages of this method are:
- Using this method, we only transfer data, not database objects, settings or permissions.
- Using this method, we are required to create and maintain format files for each table or view you want to transfer (if it does not exist on the destination database).
- It may not support some data types or features that are specific to certain versions or editions of SQL Server.
Best fit use case:
- The BCP method is the most frequently used method I use to move data between servers, I use the BCP method whenever I need to copy more than a single table of few hundred row and as up to three to 5 tables.
Less the that I will consider using the Import Scripts and more than that I will consider using the backup method.
Import script.
We will create an INSERT script via the Generate Script option. The generated result is an SQL script containing both the CREATE statements for the database objects and the INSERT statements for the data.
The advantages of this method are:
- The generated result is an SQL script containing both the CREATE statements for the database objects (including tables, indexes, views, stored procedure act’) and the INSERT statements for the data.
- The generated script is an SQL that can be read and manipulated by the DBA for get different results.
The disadvantages of this method are:
- The generated script file, in most cases, will be a very large that is difficult to manage, execute, move a round.
- The generated script may fail or cause errors if there are dependencies or conflicts between objects or data.
Best fit use case:
- I only use this option if I need to copy small chunks of data between servers.
Export & Import wizard
The Export & Import wizard is a nice util with different inputs and output options but unfortunately, from my experience many DBAs are using this tool to export and import SQL data via text files.
The single advantage I see in this method is when we will use it to export the data into none SQL environments (for example Excel) and assign different separators than the defaults comma or tab if our data is sensitive to these characters.
The same for the Imports wizard, that I use it to Import data into SQL only if the data is separated with nonstandard separators.
Summery
As you can see, each method has its advantages and disadvantages depending on your requirements and scenarios. You should evaluate them carefully before choosing one for your data transfer needs.
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