gitlab-org--gitlab-foss/db/migrate/20170516153305_migrate_assignee_to_separate_table.rb

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# See http://doc.gitlab.com/ce/development/migration_style_guide.html
# for more information on how to write migrations for GitLab.
class MigrateAssigneeToSeparateTable < ActiveRecord::Migration[4.2]
include Gitlab::Database::MigrationHelpers
# Set this constant to true if this migration requires downtime.
DOWNTIME = false
# When a migration requires downtime you **must** uncomment the following
# constant and define a short and easy to understand explanation as to why the
# migration requires downtime.
# DOWNTIME_REASON = ''
# When using the methods "add_concurrent_index", "remove_concurrent_index" or
# "add_column_with_default" you must disable the use of transactions
# as these methods can not run in an existing transaction.
# When using "add_concurrent_index" or "remove_concurrent_index" methods make sure
# that either of them is the _only_ method called in the migration,
# any other changes should go in a separate migration.
# This ensures that upon failure _only_ the index creation or removing fails
# and can be retried or reverted easily.
#
# To disable transactions uncomment the following line and remove these
# comments:
# disable_ddl_transaction!
def up
drop_table(:issue_assignees) if table_exists?(:issue_assignees)
if Gitlab::Database.mysql?
execute <<-EOF
CREATE TABLE issue_assignees AS
SELECT assignee_id AS user_id, id AS issue_id FROM issues WHERE assignee_id IS NOT NULL
EOF
else
ActiveRecord::Base.transaction do
execute('LOCK TABLE issues IN EXCLUSIVE MODE')
execute <<-EOF
CREATE TABLE issue_assignees AS
SELECT assignee_id AS user_id, id AS issue_id FROM issues WHERE assignee_id IS NOT NULL
EOF
execute <<-EOF
CREATE OR REPLACE FUNCTION replicate_assignee_id()
RETURNS trigger AS
$BODY$
BEGIN
if OLD IS NOT NULL AND OLD.assignee_id IS NOT NULL THEN
DELETE FROM issue_assignees WHERE issue_id = OLD.id;
END IF;
if NEW.assignee_id IS NOT NULL THEN
INSERT INTO issue_assignees (user_id, issue_id) VALUES (NEW.assignee_id, NEW.id);
END IF;
RETURN NEW;
END;
$BODY$
LANGUAGE 'plpgsql'
VOLATILE;
CREATE TRIGGER replicate_assignee_id
BEFORE INSERT OR UPDATE OF assignee_id
ON issues
FOR EACH ROW EXECUTE PROCEDURE replicate_assignee_id();
EOF
end
end
end
def down
drop_table(:issue_assignees) if table_exists?(:issue_assignees)
if Gitlab::Database.postgresql?
execute <<-EOF
DROP TRIGGER IF EXISTS replicate_assignee_id ON issues;
DROP FUNCTION IF EXISTS replicate_assignee_id();
EOF
end
end
end