I had to migrate from a mySql based ruby on rails app to using postgresql. No problems but one so far, and I don't know how to solve it.
The migration of data brought ids along with it, and postgresql is now having problems with existing ids: it's not clear to me where it gets the value that it uses to determine the base for nextval: it certainly isn't the highest value in the column, although you might think that would be a good idea. In any case, it's now colliding with existing id values. id column, created from a standard RoR migration is defined as
not null default nextval('geopoints_id_seq'::regclass)
Is there some place that the value it uses as a base can be hacked? This problem could now arise in any of 20 or so tables: I could use
'select max(id) from <table_name>'
but that seems to make the idea of an autoincrement column pointless.
How is this best handled?
There is a
reset_pk_sequences!
method on the Postgres adapter. You can call it and it will set it to max(id) + 1, which is probably what you want.In some projects I get data ETL'ed in often enough to warrant a rake task to do this for all models, or for a specified model. Here's the task - include it in some Rakefile or in it's own under lib/tasks:
Now you can run this either for all models (defined under RAIS_ROOT/app/models) using
rake reset_sequences
, or for a specific model by passing in a class name.