こんにちは私は現在、MicrosoftSQLServerを使用するRails2プロジェクトに取り組んでいます。バックグラウンドプロセスを可能にするdelayed_jobgemを実装しようとしています。これを行うには、移行時に次のようなテーブルを作成する必要があります。
class CreateDelayedJobs < ActiveRecord::Migration
def self.up
create_table :delayed_jobs, :force => true do |table|
table.integer :priority, :default => 0 # Allows some jobs to jump to the front of the queue
table.integer :attempts, :default => 0 # Provides for retries, but still fail eventually.
table.text :handler # YAML-encoded string of the object that will do work
table.text :last_error # reason for last failure (See Note below)
table.datetime :run_at # When to run. Could be Time.zone.now for immediately, or sometime in the future.
table.datetime :locked_at # Set when a client is working on this object
table.datetime :failed_at # Set when all retries have failed (actually, by default, the record is deleted instead)
table.string :locked_by # Who is working on this object (if locked)
table.timestamps
end
add_index :delayed_jobs, [:priority, :run_at], :name => 'delayed_jobs_priority'
end
def self.down
drop_table :delayed_jobs
end
end
3つの日時列があることに注意してください。ただし、SQLServer構文を使用して純粋なSQLでこれを行う必要があります。W3スクールによると:
timestamp Stores a unique number that gets updated every time a row gets created or modified. The timestamp value is based upon an internal clock and does not correspond to real time. Each table may have only one timestamp variable
CREATE TABLE delayed_jobs
{
id uniqueidentifier,
priority int,
attempts int,
handler text,
last_error text,
run_at timestamp,
locked_at timestamp,
failed_at timestamp,
locked_by varchar(255)
};
- この単一のタイムスタンプ制限を回避するにはどうすればよいですか?
- インデックスを追加するにはどうすればよいですか?