Items tagged postgresql, migrations
Filters: postgresql × migrations × Sorted by date
pgroll (via) “Zero-downtime, reversible, schema migrations for Postgres”
I love this kind of thing. This one is has a really interesting design: you define your schema modifications (adding/dropping columns, creating tables etc) using a JSON DSL, then apply them using a Go binary.
When you apply a migration the tool first creates a brand new PostgreSQL schema (effectively a whole new database) which imitates your new schema design using PostgreSQL views. You can then point your applications that have been upgraded to the new schema at it, using the PostgreSQL search_path setting.
Old applications can continue talking to the previous schema design, giving you an opportunity to roll out a zero-downtime deployment of the new code.
Once your application has upgraded and the physical rows in the database have been transformed to the new schema you can run a --continue command to make the final destructive changes and drop the mechanism that simulates both schema designs at once. # 30th January 2024, 9:27 pm
migra (via) This looks like a very handy tool to have around: run “migra postgresql:///a postgresql:///b” and it will detect and output the SQL alter statements needed to modify the first PostgreSQL database schema to match the second. It’s written in Python, running on top of SQLAlchemy. # 26th February 2022, 11:23 pm
How to Create an Index in Django Without Downtime (via) Excellent advanced tutorial on Django migrations, which uses a desire to create indexes in PostgreSQL without locking the table (with CREATE INDEX CONCURRENTLY) to explain the SeparateDatabaseAndState and atomic features of Django’s migration framework. # 11th April 2019, 3:06 pm