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Database Set up Liquibase
Liquibase is an open-source database schema change management solution which enables you to manage revisions of your database changes easily. Liquibase makes it easy for anyone involved in the application release process to:
- Eliminate errors and delays when releasing databases.
- Deploys and Rollback changes for specific versions without needing to know what has already been deployed.
- Deploy database and application changes together so they always stay in sync.
Yes. Since each change is independent, database changes that had been made in a different branch, then merged in will be run the next time Liquibase is run. You may run into a problem with the order that the statements are ran, but any issues you have can be easily solved by re-ordering the changelog files.
Liquibase Community is released under the Apache License, version 2.0. Liquibase Pro is released under a commercial license. The main Liquibase jar file also contains commercially licensed Liquibase Pro code that is only active when a license key is provided.
Liquibase uses a distributed locking system to only allow one process to update the database at a time. The other processes will simply wait until the lock has been released.
The source is available from the main liquibase.org/download page or directly from Github.
How does Liquibase compare to tools that compare development database with production databases to generate change lists?
Liquibase works better because it understands what the changes are. For example, a database comparison program would simply see the "person" table on integration has a "firstname" and a "lastname" column, but on live, the "person" table has a "name" column. It would report that you need to drop the "name" column and add a "firstname" and a "lastname" column. While this would leave you with the correct schema, you would lose everyone's name in the process. With Liquibase, you would have a changeset that says "rename 'name' to 'lastname' and add a 'firstname' column" or, even better, "split the name column on a space and place the values in new 'firstname' and 'lastname' columns, then drop the ‘name' column." Knowing why they are different allows changes to production databases without the fear of losing valuable data.
Liquibase uses a distributed locking system to only allow one process to update the database at a time. The other processes will simply wait until the lock has been released.
Yes. Since each change is independent, database changes that had been made in a different branch, then merged in will be run the next time Liquibase is run. You may run into a problem with the order that the statements are ran, but any issues you have can be easily solved by re-ordering the changelog files.
Liquibase is designed to manage the structure and code. It’s great for concise data fixes and updates, but massive datasets are better handled with vendor-specific tooling or a purpose-built tool.
Nevertheless, you can use the loadData Change Type and load data from a CSV file into an existing table when you add it to your changelog.
Why not just an "id" tag? The main reason for both the author the id attribute tag is because it is too easy for more than one person to a tag with the same "id" value–especially when using multiple branches. The source control system is going to resolve and merge two changesets added on different branches, but it won't care that there are two different changesets with the same "id", and once a changeset has been run against a database with one id, you can't (easily) change it. By also determining changeset uniqueness based on an author tag, the chance of duplicates is lowered.
There are times an organization would not want to have changes tied back to a particular individual or if the original author isn't actually known. If this is the case, simply make up a value such as "UNKNOWN".
We do not currently have a way to specify vendor specific extensions to the create table tag, and so you would need to use the tag and specify your create table statement manually. Of course you would be able to configure your mysql install to use innodb as the default storage engine with default-storage-engine=INNODB.