Migrations

Tables that have been upgraded to crrs need some extra handling during schema modification. This is because bookkeeping metadata needs to be migrated as well.

When modifying the schema of a crr:

1. Be sure you start that modification with a call to crsql_begin_alter
2. Complete that modification with a call to crsql_commit_alter

calls to crsql_begin_alter and crsql_commit_alter may be nested as well as occur in an outer transaction.

If the alter fails, all levels of transactions and savepoints will be rolled back.

Usage

SELECT crsql_begin_alter('table_name');
...
SELECT crsql_commit_alter('table_name');

Example

SELECT crsql_begin_alter('foo');
ALTER TABLE foo ADD COLUMN c TEXT;
SELECT crsql_commit_alter('foo');
SELECT crsql_begin_alter('bar');
ALTER TABLE bar ADD COLUMN baz TEXT;
SELECT crsql_commit_alter('bar');

Currently supported schema alterations:

1. add columns
2. drop columns
3. rename columns
4. modifying indices

Support for renaming tables is a work in progress.

Automatic Migrations

Automatic migrations work by diffing the current schema of the database with a desired schema. Alter table and index statements are automatically generated and applied to the database.

This will be in the v0.10 release and can be accomplished like so:

SELECT crsql_migrate('contents of your schema file');