The Ktor or Exposed frameworks do not have any built-in support for database migrations. What's the recommended way to do this?
If you are using Ktor with Gradle I would recommend using Flyway programatically inside the entry point of your Application. This way it could easily be a part of your Continuous Delivery pipeline. You can see the Flyway docs using API here: https://flywaydb.org/documentation/api/
What I essentially do though is add the dependency (using Kotlin DSL):
implementation("org.flywaydb:flyway-core:6.5.2")
And then all you need to do is create an instance of Flyway and call migrate when you load your module:
fun Application.module() {
Flyway.configure().dataSource(/*config to your DB*/).load().migrate()
//the rest of your application
routing {
}
}
You could of course extract the creation of Flyway to your DI tool (e.g. Koin) and add some logging to show progress.
This way your DB will be migrated (if necessary) every time just before your app is started.
As for writing up the actual migration the official docs are very helpful. What you essentially need to do is:
Make sure you have the required directory for migration files - src/main/resources/db/migration by default ).
Write plain SQL in separate migration files in the above directory. The filenames need to stick to the convention too (by default: start with capital V then a number, which you will increment for each new migration, double underscore - this tricked me at the beginning ;) - and a snake_case description, e.g. V1__Create_person_table.sql)
Run the app and observe magic :D
Database tables are migrated at deployment via Flyway and scripts can be added in db/migrations folder to add new tables or execute queries like inserting data etc on server startup.
(https://github.com/arun0009/kotlin-ktor-exposed-sample-api)
Here's how Flyway works: https://flywaydb.org/getstarted/how
Download, install, and configure Flyway (See https://flywaydb.org/getstarted/firststeps/commandline)
Point it to a database, which will be the location of flyway_schema_history
Write your migration files for create table or insert data following their naming convention: V<version number>__<migration description> and run with flyway migrate
Write your repeatable migration files for create view following their naming convention: R__<migration description> and run with flyway migrate
Write your undo migration files for drop table or delete data following their naming convention: V<version number>__<migration description> and run with flyway migrate
Check your migration status with flyway info and commit your files if you're happy
Make any necessary modifications are rerun migration. Repeat and commit.
In case if this is a one time activity, you can try using a Off-the shelf utility like SQL Data Compare.
To make this happen, you would need to ensure that both the databases are accessible locally from your machine so that you can create 2 DB connections and run a comparison against them.
At the end of comparison, you can get a Auto-Generated SQL Script out of it to run against your new schema and make it sychronized.
In case if you wish to compare Schema Objects as well, again Red-Gate provides a similar Schema Compare tool, which they have now started to call as SQL Compare (God knows why !!). This utility would also provide similar auto-generated script to help you.
But, again Red Gate is good for one-time migration and you can use this with their Trial version for a period of 30 days. For similar activity in regular basis, you would need to buy the Licensed version of same software.
For Data Migrantion, I use Navicat Premium which i find very easy to use, but it is not an open source. If you are looking for an Open Source Tool, then You can use SQLines Data which is an open source (Apache License 2.0), scalable, parallel high performance data transfer and schema conversion tool that you can use for database migrations and ETL processes.
SQLines
It is available for Linux, Windows, both 64-bit and 32-bit platforms.
You can also use SQLines Data for cross-platform database migration. The tool migrates table definitions, constraints, indexes and transfers data.
This how you can start with SQLines:
Download and unzip the file, no installation is required
Run sqldataw.exe on Windows to launch the GUI version
Run ./sqldata on Linux to launch the command line tool.
And There are Migration guidelines available for specific databases.Guidelines
I have 2 files: db structure, and db data sql files.
(we are not in part of project where we are creating alter files yet).
Is there a way to achieve running these files before build each time if any of them changed using maven?
The only idea I have is to rename the files (bring the version up) after each change to them making sure flyaway will pick it up.
Is there a smarter way, perhaps using API or some other 'trick'?
Thanks
--MB
You can use flyway migrate with the following configuration
validationMode=ALL
validationErrorMode=CLEAN
For each sql migration a CRC32 checksum is calculated when the sql script is executed. The validate mechanism checks if the sql migrations in the classpath still has the same checksum as the sql migration already executed in the database.
validationErrorMode=CLEAN is exclusively intended as a convenience for development. Even tough we strongly recommend not to change migration scripts once they have been checked into SCM and run, this provides a way of dealing with this case in a smooth manner. The database will be wiped clean automatically, ensuring that the next migration will bring you back to the state checked into SCM.
This configuration can be used from API, maven plugin or command line.
With newer Flyway, you would use
flyway.setInitOnMigrate(true);
flyway.setCleanOnValidationError(true);
flyway.setValidateOnMigrate(true);
To drop everything if the checksum of the file changes or the version table is missing.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Stored procedures/DB schema in source control
What's the best way to version control my tables, views, sprocs, etc? Preferably automated or at least semi-automated :)
Thanks
I asked this one yesterday and got some nice responses:
Stored procedures/DB schema in source control
The articles from K Scott Allen say it all:
http://odetocode.com/Blogs/scott/archive/2008/01/31/11710.aspx
Write migration scripts for all db changes and keep them in a repository. Enforce a policy of making all changes to the db only by running a script; that way there is a record of what has been done, and a way to revert it. Investigate whether there's a migrations framework available for your favorite language/db combination.
I use Visual Studio 2008 Pro create Database projects (Other project types -> Database). We already use SVN as a code repository, so a project with a bunch of .sql files representing your stored procedures is just another thing to put in the repository - you can see diffs/history etc. This works the same with VSS or any other repository you use.
The nice thing about Database projects is that your project will remember your connection string, and all you have to do is right click on a .sql file (or select all of them at once!) and select run to update it in the db. This makes it easy to update your .sql files from the repository and run them all to update all your stored procedures, verifying your database is updated in seconds.
You can also select create a LINQ project (Visual C# -> Database) and store all your LINQ code in your repository.
Hope that helps!
If you were super lazy you could use the SMO (SQL Server Management Objects) or if using SQL Server prior to 2005 the DMO (distributed managmeent objects) to script out all tables/views/stored procedures daily and then compare the script to the script in source control and if there are any changes check the new version in. You won't be able to necessarily have as pretty of a script as if you just created all db changes in scripts, but at least you can recreate all tables/stored procedures/views. For example, in my table creation scripts there are often comments.
Here is an article to get you started on scripting: http://www.sqlteam.com/article/scripting-database-objects-using-smo-updated.
Again, this is mainly if you are too lazy to bother with version control and it won't help if you change something twice in one day. Also any data migration scripts still have to be saved and checked in because this won't pick up ad hoc SQL, only database objects.
I have written a DDL trigger which logs all the changes done to the definition of SQL objects (triggers, tables, SP, view etc). I could very well invoke extended SP from the trigger and store the details in another Database and use that as repository.
But if your team is really disciplined any source control should do the trick. The trigger is used as an audit mechanism and it's ideal for teams which are geographically scattered.
Try Randolph, One of the best SQL Version control tools I know.
I'm using Visual Studio Database edition which can export the schema from SQL Server in to a Visual Studio project. This is then stored in Source Control and can be deployed where ever needed. The VS Database project is just a bunch of scripts though and it's a clunky way of working.
A more robust method would be to use a database migration framework and if you're working with .Net check out this blog post for a good description http://flux88.com/NETDatabaseMigrationToolRoundup.aspx.
Update
As mentioned in the comments, this page is no more. So here is the last known snapshot from wayback machine http://web.archive.org/web/20080828232742/http://flux88.com/NETDatabaseMigrationToolRoundup.aspx
I often run into the following problem.
I work on some changes to a project that require new tables or columns in the database. I make the database modifications and continue my work. Usually, I remember to write down the changes so that they can be replicated on the live system. However, I don't always remember what I've changed and I don't always remember to write it down.
So, I make a push to the live system and get a big, obvious error that there is no NewColumnX, ugh.
Regardless of the fact that this may not be the best practice for this situation, is there a version control system for databases? I don't care about the specific database technology. I just want to know if one exists. If it happens to work with MS SQL Server, then great.
In Ruby on Rails, there's a concept of a migration -- a quick script to change the database.
You generate a migration file, which has rules to increase the db version (such as adding a column) and rules to downgrade the version (such as removing a column). Each migration is numbered, and a table keeps track of your current db version.
To migrate up, you run a command called "db:migrate" which looks at your version and applies the needed scripts. You can migrate down in a similar way.
The migration scripts themselves are kept in a version control system -- whenever you change the database you check in a new script, and any developer can apply it to bring their local db to the latest version.
I'm a bit old-school, in that I use source files for creating the database. There are actually 2 files - project-database.sql and project-updates.sql - the first for the schema and persistant data, and the second for modifications. Of course, both are under source control.
When the database changes, I first update the main schema in project-database.sql, then copy the relevant info to the project-updates.sql, for instance ALTER TABLE statements.
I can then apply the updates to the development database, test, iterate until done well.
Then, check in files, test again, and apply to production.
Also, I usually have a table in the db - Config - such as:
SQL
CREATE TABLE Config
(
cfg_tag VARCHAR(50),
cfg_value VARCHAR(100)
);
INSERT INTO Config(cfg_tag, cfg_value) VALUES
( 'db_version', '$Revision: $'),
( 'db_revision', '$Revision: $');
Then, I add the following to the update section:
UPDATE Config SET cfg_value='$Revision: $' WHERE cfg_tag='db_revision';
The db_version only gets changed when the database is recreated, and the db_revision gives me an indication how far the db is off the baseline.
I could keep the updates in their own separate files, but I chose to mash them all together and use cut&paste to extract relevant sections. A bit more housekeeping is in order, i.e., remove ':' from $Revision 1.1 $ to freeze them.
MyBatis (formerly iBatis) has a schema migration, tool for use on the command line. It is written in java though can be used with any project.
To achieve a good database change management practice, we need to identify a few key goals.
Thus, the MyBatis Schema Migration System (or MyBatis Migrations for short) seeks to:
Work with any database, new or existing
Leverage the source control system (e.g. Subversion)
Enable concurrent developers or teams to work independently
Allow conflicts very visible and easily manageable
Allow for forward and backward migration (evolve, devolve respectively)
Make the current status of the database easily accessible and comprehensible
Enable migrations despite access privileges or bureaucracy
Work with any methodology
Encourages good, consistent practices
Redgate has a product called SQL Source Control. It integrates with TFS, SVN, SourceGear Vault, Vault Pro, Mercurial, Perforce, and Git.
I highly recommend SQL delta. I just use it to generate the diff scripts when i'm done coding my feature and check those scripts into my source control tool (Mercurial :))
They have both an SQL server & Oracle version.
I wonder that no one mentioned the open source tool liquibase which is Java based and should work for nearly every database which supports jdbc. Compared to rails it uses xml instead ruby to perform the schema changes. Although I dislike xml for domain specific languages the very cool advantage of xml is that liquibase knows how to roll back certain operations like
<createTable tableName="USER">
<column name="firstname" type="varchar(255)"/>
</createTable>
So you don't need to handle this of your own
Pure sql statements or data imports are also supported.
Most database engines should support dumping your database into a file. I know MySQL does, anyway. This will just be a text file, so you could submit that to Subversion, or whatever you use. It'd be easy to run a diff on the files too.
If you're using SQL Server it would be hard to beat Data Dude (aka the Database Edition of Visual Studio). Once you get the hang of it, doing a schema compare between your source controlled version of the database and the version in production is a breeze. And with a click you can generate your diff DDL.
There's an instructional video on MSDN that's very helpful.
I know about DBMS_METADATA and Toad, but if someone could come up with a Data Dude for Oracle then life would be really sweet.
Have your initial create table statements in version controller, then add alter table statements, but never edit files, just more alter files ideally named sequentially, or even as a "change set", so you can find all the changes for a particular deployment.
The hardiest part that I can see, is tracking dependencies, eg, for a particular deployment table B might need to be updated before table A.
For Oracle, I use Toad, which can dump a schema to a number of discrete files (e.g., one file per table). I have some scripts that manage this collection in Perforce, but I think it should be easily doable in just about any revision control system.
Take a look at the oracle package DBMS_METADATA.
In particular, the following methods are particularly useful:
DBMS_METADATA.GET_DDL
DBMS_METADATA.SET_TRANSFORM_PARAM
DBMS_METADATA.GET_GRANTED_DDL
Once you are familiar with how they work (pretty self explanatory) you can write a simple script to dump the results of those methods into text files that can be put under source control. Good luck!
Not sure if there is something this simple for MSSQL.
I write my db release scripts in parallel with coding, and keep the release scripts in a project specific section in SS. If I make a change to the code that requires a db change, then I update the release script at the same time.
Prior to release, I run the release script on a clean dev db (copied structure wise from production) and do my final testing on it.
I've done this off and on for years -- managing (or trying to manage) schema versions. The best approaches depend on the tools you have. If you can get the Quest Software tool "Schema Manager" you'll be in good shape. Oracle has its own, inferior tool that is also called "Schema Manager" (confusing much?) that I don't recommend.
Without an automated tool (see other comments here about Data Dude) then you'll be using scripts and DDL files directly. Pick an approach, document it, and follow it rigorously. I like having the ability to re-create the database at any given moment, so I prefer to have a full DDL export of the entire database (if I'm the DBA), or of the developer schema (if I'm in product-development mode).
PLSQL Developer, a tool from All Arround Automations, has a plugin for repositories that works OK ( but not great) with Visual Source Safe.
From the web:
The Version Control Plug-In provides a tight integration between the PL/SQL Developer IDE >>and any Version Control System that supports the Microsoft SCC Interface Specification. >>This includes most popular Version Control Systems such as Microsoft Visual SourceSafe, >>Merant PVCS and MKS Source Integrity.
http://www.allroundautomations.com/plsvcs.html
ER Studio allows you to reverse your database schema into the tool and you can then compare it to live databases.
Example: Reverse your development schema into ER Studio -- compare it to production and it will list all of the differences. It can script the changes or just push them through automatically.
Once you have a schema in ER Studio, you can either save the creation script or save it as a proprietary binary and save it in version control. If you ever want to go back to a past version of the scheme, just check it out and push it to your db platform.
There's a PHP5 "database migration framework" called Ruckusing. I haven't used it, but the examples show the idea, if you use the language to create the database as and when needed, you only have to track source files.
We've used MS Team System Database Edition with pretty good success. It integrates with TFS version control and Visual Studio more-or-less seamlessly and allows us to manages stored procs, views, etc., easily. Conflict resolution can be a pain, but version history is complete once it's done. Thereafter, migrations to QA and production are extremely simple.
It's fair to say that it's a version 1.0 product, though, and is not without a few issues.
You can use Microsoft SQL Server Data Tools in visual studio to generate scripts for database objects as part of a SQL Server Project. You can then add the scripts to source control using the source control integration that is built into visual studio. Also, SQL Server Projects allow you verify the database objects using a compiler and generate deployment scripts to update an existing database or create a new one.
In the absence of a VCS for table changes I've been logging them in a wiki. At least then I can see when and why it was changed. It's far from perfect as not everyone is doing it and we have multiple product versions in use, but better than nothing.
I'd recommend one of two approaches. First, invest in PowerDesigner from Sybase. Enterprise Edition. It allows you to design Physical datamodels, and a whole lot more. But it comes with a repository that allows you to check in your models. Each new check in can be a new version, it can compare any version to any other version and even to what is in your database at that time. It will then present a list of every difference and ask which should be migrated… and then it builds the script to do it. It’s not cheap but it’s a bargain at twice the price and it’s ROI is about 6 months.
The other idea is to turn on DDL auditing (works in Oracle). This will create a table with every change you make. If you query the changes from the timestamp you last moved your database changes to prod to right now, you’ll have an ordered list of everything you’ve done. A few where clauses to eliminate zero-sum changes like create table foo; followed by drop table foo; and you can EASILY build a mod script. Why keep the changes in a wiki, that’s double the work. Let the database track them for you.
Schema Compare for Oracle is a tool specifically designed to migrate changes from our Oracle database to another. Please visit the URL below for the download link, where you will be able to use the software for a fully functional trial.
http://www.red-gate.com/Products/schema_compare_for_oracle/index.htm
Two book recommendations: "Refactoring Databases" by Ambler and Sadalage and "Agile Database Techniques" by Ambler.
Someone mentioned Rails Migrations. I think they work great, even outside of Rails applications. I used them on an ASP application with SQL Server which we were in the process of moving to Rails. You check the migration scripts themselves into the VCS.
Here's a post by Pragmatic Dave Thomas on the subject.