data-migration

Are there any Ruby gems/libraries that help you migrate from an old DB structure to a new structure? ActiveRecord migrations do a good job keeping track of a new db structure, but I wonder if there's something that helps you migrate an entire legacy db to a new structure: transfer_from(:source_table => 'person', :destination_table => 'dudes_and_dudets') do from :name, :to => :full_name from :dob, :to => :age do |dob| # this would, for example, load the result (Date.today - dob)/60/60/24/365 # of the block into :age end end (I realize you could do these transforms just as easily with AR, but I

I have a web application using sqlalchemy (within Pylons). I need to effiently change the schema to be able to change the production version at least on a daily basis, maybe more, without losing the data. I have played a little bit with sqlalchemy-migrate over the week-end and I would say that it gave me a bad impression. First I think it cannot help with migration between two databases engines ; that's something that could probably be done with sqlalchemy alone. Second the docs do not seem up to date. I had to change some command-line options, like giving the repository path at each command,

DISCLAIMER: This question is similar to the stack overflow question here , but none of those answers work for my problem, as I will explain later. I'm trying to copy a large table (~40M rows, 100+ columns) in postgres where a lot of the columns are indexed. Currently I use this bit of SQL: CREATE TABLE <tablename>_copy (LIKE <tablename> INCLUDING ALL); INSERT INTO <tablename>_copy SELECT * FROM <tablename>; This method has two issues: It adds the indices before data ingest, so it will take much longer than creating the table without indices and then indexing after copying all of the data. This

After making some changes in my models (eg. new field in a model and a new model) what is the best way of reflecting these changes to my populated database? PS: I wanted to see many solutions in one place rated. Apparently more solutions are already listed here . Farinha I've asked a similar question here and got quite a few answers. There are quite a lot of ways of doing it, like manually doing the dumping and reloading with SQL, using fixtures or using one of the "emerging" schema-evolution packages for Django: Django Evolution South dmigrations (there's a DjangoCon video of a panel on

We are looking to upgrade from Apache Solr 4.7 to ApacheSolr 5.2. upgraded server and run script to upgrade the data index. it is showing below errors. ./upgradeindex.sh -t 5 /home/solr Target version is 5 Downloading http://central.maven.org/maven2/org/apache/lucene/lucene-backward-codecs/4.10.4/lucene-backward-codecs-4.10.4.jar curl: (7) couldn't connect to host Downloading http://central.maven.org/maven2/org/apache/lucene/lucene-backward-codecs/5.5.4/lucene-backward-codecs-5.5.4.jar curl: (7) couldn't connect to host Downloading http://central.maven.org/maven2/org/apache/lucene/lucene

I have one table: drupal.comments , with amongst others, the columns: cid: primary key uid: foreign key to users table, optional name: varchar, optional email: varchar, optional The description says: UID is optional, if 0, comment made by anonymous; in that case the name/email is set. I want to split this out into two tables rails.comments and rails.users , where there is always a user: id: primary key users_id: foreign key, always set. So, for each drupal.comment, I need to create either a new user from the drupal.comments.name/drupal.comments.email and a rails.comment where the rails.comment

If data model changes,and need be backward compatible to use old data source,we must consider data migration for database application. What is the common strategy for core data in iOS dev ? Is there any mature open source project to handle this problem ? 来源： https://stackoverflow.com/questions/4601339/what-is-common-data-migration-strategy-for-core-data-in-ios-development