Google Cloud Platform Japan 公式ブログ: Google Cloud Datastoreでのデータ整理の考え方

Google Cloud Datastoreでのデータ整理の考え方

2015年8月6日木曜日

* この投稿は、米国時間 8 月 5 日、Google Cloud Platform Developer Programs Engineer の Jon Wayne Parrott によって投稿されたものの抄訳です。Google Cloud Datastore

マルチユーザーブログ

Wiki

Google Cloud Storage マルチユーザーブログ User

Id	Username	Name
1	tonystark	Tony Stark
2	dianaprince	Diana Prince

Post

id	user_id	content
1	1	Hello, world!
2	2	Another post

SELECT * FROM Posts WHERE user_id = {user_id}

エンティティカインド

Key	Data
(Post, 1)	{"user": Key(User, tonystark), "content": "Hello, World!"}
(Post, 2)	{"user": Key(User, dianaprince), "content": "Another post"}
(User, tonystark)	{"name": "Tony Stark"}
(User, dianaprince)	{"name": "Diana Prince"}

datastore.Query(kind='Post', filters=[('user', '=', Key('User', username))])

強い整合性と結果整合性のどちらかを選択できます祖先/1.post
/2.post
/tonystark.user
/dianaprince.user/tonystark.user
/1.post
/dianaprince.user
/2.post/tonystark.user/1.post

Key	Data
(User, tonystark)	{"name": "Tony Stark"}
(User, tonystark, Post, 1)	{"content": "Hello, World!"}
(User, dianaprince)	{"name": "Diana Prince"}
(User, dianaprince, Post, 2)	{"content": "Another post"}

datastore.Query(kind='Post', ancestor=Key('User', username))注： datastore.Query(kind='Post') Wiki /home.page
/ current.revision
/ 05-29-2015-10-30-27.revision
/ 05-20-2015-06-33-11.revision
/another.page
/ current.revision
/ 04-10-2015-11-23-10.revision注： def save_page(ds, page, content):
   with ds.transaction():
       now = datetime.datetime.utcnow()
       current_key = path_to_key(ds, '{}.page/current.revision'.format(page))
       revision_key = path_to_key(ds, '{}.page/{}.revision'.format(page, now))

       if ds.get(revision_key):
           raise AssertionError("Revision %s already exists" % revision_key)

       current = ds.get(current_key)

       if current:
           revision = datastore.Entity(key=revision_key)
           revision.update(current)
           ds.put(revision)
       else:
           current = datastore.Entity(key=current_key)

       current['content'] = content

       ds.put(current)
datastore.Query(kind='revision', ancestor=Key('page', home))def restore_revision(ds, page, revision):
   save_page(ds, page, revision['content'])