SSDT + DACFx = Cool Database Version Control
For years, building and deploying a database to multiple clients was all pain and a lot of work. I have relied mostly in hand-coded solution to keep my sanity intact. The goal was simply to synchronize all databases deployed to various clients from a single schema which our company maintains. The goal was very simple, yet it was easier said than done. Often, one or more of these databases gets less and less updates over time which made things difficult to track. Some of these are of our own doing and some due to the inherent nature of our business as we don’t necessarily and automatically update databases as we wish. Clients need to sign up and approve of the updates and upgrades to the system and the databases.
In our case, there are tens of thousands of stored procedures to maintain and hundreds of tables, indexes and other SQL objects to track.These objects should be also in synched with the applications as version 1.0 of apps have different sets of Sql Server objects than application version 2.00. And we maintain up to 3 different versions hoping the clients would sign-up to upgrade to the latest faster than we solve all these complications. Some of these objects evolved from more than a decade of operation. In the end, databases get out of synched from the model that we have at hand as versions upon versions in various clients change. Today, the challenges are even greater. As we transition to a more faster and smaller roll out of updates (people refer nowadays to a more ‘agile’ way of evolving applications), new features, changes, fixes, deprecations, or whatever is on the plate increase the chances of our database out there getting out of synched.
A Viable Solution : SSDT and DACFx
Now enter the realm of SSDT and DACFx, it has provided us a free and automated way of doing what yesterday was a major headache for most of us. Some semblance of these workings started with SQL Server 2005 SP4 but I have waited for SSDT to have gone out to fully embrace the solution. Now there is that ‘silver bullet’ that would allow us to slay a werewolf of database proportions. So what are these tools to build databases incrementally and have all the increments deployed in an automatic manner (yes, it only involves a single command with a few parameters to dabble with!)?
All we need now are the following:
- SQL Server Data Tools (SSDT). A free database development tool that will allow us to design our databases and package it for deployment from version 1.0 to a series of minor and major updates to its schema. It is better to check out what it is if you still have not heard of SSDT. Coupled with DACFx, you can build Data Tier Applications (DAC).
- DACFx. SQL Server Data-Tier Application Framework which is a set of tools, API’s and services intended to simplify our development, deployment and management of SQL Server schemas. The framework specifically allows us to build Data Tier Applications (DAC).
- SQLPackage.Exe, a DAC tool use to deal with DACPACs and a lot more.
How These Things Work
Here, I would simply present a typical scenario everyone can relate and see how these tools work. Our goal is to deploy TESTDB v1.0 and update it with TESTDB v1.1. Using SSDT, I will have to author my TESTDB v1.0 with probably Table1 and StoredProcedure1 in it. Then I have to get the database snapshot.
This forces SSDT to generate a DACPAC file containing metadata and instructions on how my TESTDB v1.0 is like when it is deployed. For this article I got the file TESTDB_20130301_11-32-20.dacpac under the snapshots folder of the project. The file naming gives me instant version management of some sort and that is neat. Using SQLPackage.Exe, I could go to any client’s SQL Server, fire up CMD and run TESTDB_20130301_11-32-20.dacpac.
SQLPackage.Exe will proceed to deploy TESTDB v1.0 on any instance of SQL Server that I want. I basically only need to know the proper connection string that I can use for the process. But of course there is more to that, but I leave all that outside of this article for now as I wanted to show how easy it is all these can be achieved.
At this point in time, I got the following:
- A simple, stand-alone dacpac file that I can use to deploy TESTDB v1.0 on more servers. I can have others or the clients do that for me. No more of those hand-coded scripts that could easily get tampered or accidentally modified for me. I can keep this file knowing this sets up the schema version 1.0 for my TESTDB. And I can use it weeks, months or even years after without worrying to recall what it needs to do.
- A ‘testdb1′ database sitting on a new server
- and a head-ache free afternoon
At some point in time, I probably might need to upgrade TESTDB with new tables and stored procs. We can refer to this as TESTDB v1.1. I can do that with SSDT by opening the TESTDB project, add the new objects and have a snapshot once again of the latest version of TESTDB to get a new DACPAC associated to TESTDB’s new version/updates. I just have to run the new DACPAC file on new or existing servers. This is where these tools get interesting and there are possibly varying outcomes depending on what SQLPackage.Exe encounters:
- if testdb1 exists in the target server, SQLPackage.EXE will update the schema as necessary. It will check existing objects, leave it as is or update it as necessary and add new ones. It will do this without DATA LOSS. Yes, no DATA LOSS.
- if testdb1 does not exist in the target server, it will simply create testdb1. Objects from previous versions (e.g. TESTDB v1.0) will be recreated up to the latest version (which is TESTDB v1.1)
- A possibility of DATA LOSS is also detected during this process. For example, if a certain column from v1.0 was changed from VARCHAR to INT in v1.1, SQLPackage.Exe prompts the user and cancels the entire update. THIS prevents DATA LOSS.
- A version drift is also detected during this process. A user is prompted if a modification of the database schema outside this formal and controlled process of deployment is present. Once detected, it also cancels the entire update. THIS prevents DATA LOSS and structural modifications on databases that were tweaked outside of this process for some valid reasons.
With all these free and simple yet very effective deployment tools, I’d have my weekends for more non-tech activities. Oh well, I should have gone fishing but these tools tell me to tell others so they can go fishing too.
𝗦𝘂𝗹𝗳𝘂𝗿-𝗯𝗶𝗹𝗹𝗲𝗱 𝗡𝘂𝘁𝗵𝗮𝘁𝗰𝗵, 𝘚𝘪𝘵𝘵𝘢 𝘰𝘦𝘯𝘰𝘤𝘩𝘭𝘢𝘮𝘺𝘴
Photographed in Mountain Province
Toto Gamboa is a consultant specializing on databases, Microsoft SQL Server and software development operating in the Philippines. He is currently a member and one of the leaders of Philippine SQL Server Users Group, a Professional Association for SQL Server (PASS) chapter and is one of Microsoft’s MVP for SQL Server in the Philippines. You may reach him by sending an email to firstname.lastname@example.org