65 lines
1.6 KiB
Markdown
65 lines
1.6 KiB
Markdown
# Database migration
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[Detailed information about this](http://ian-shafer.github.io/2016/02/02/db-migrations/)
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## Setup
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#### Configuration
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The credentials for each environment that could be updated is stored in the
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`env/` directory.
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***Example***
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`env/default.conf` could look like this:
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```
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#!/bin/bash
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export PSQL_OPTS="-h HOST_NAME -U USER_NAME"
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export DB_NAME=DATABASE_NAME
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```
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Create one file for each environment you'd be able to migrate.
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When `db-upgrade` is issued, it takes the first part of any name as argument and
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performs the migration on selected environment.
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`$ ./db-upgrade localhost` would for example find a file named `localhost.conf`
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and use the credentials inside for the migration.
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To avoid having to enter password for selected user on each run, just use a
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[.pgpass](http://www.postgresql.org/docs/9.3/static/libpq-pgpass.html) file.
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`db-upgrade` assumes the `default` environment should be used if it's argument
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is omitted. So, start by creating an initial `default.conf` with credentials for your localhost or some non-critical environment.
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#### Migration files
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The files in the /migrations directory are changes to the scheme, not the full
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scheme.
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The naming convention for migration files are:
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- 000.000.sql
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- 000.001.sql
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- 000.002.sql
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- 000.003.sql
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- 000.004.sql
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- ...and so on
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**Example**
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The first file, `migrations/000.000.sql` may look like this:
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```
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create table users (
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name varchar(32) not null,
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primary key (name)
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);
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```
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The second file, `migrations/000.001.sql` may look like this:
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```
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alter table users
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add email varchar(256) not null;
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```
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To do the actual migration, then just run:
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```
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# ./db-upgrade [ENVIRONMENT NAME]
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```
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