Hi Harry,
Thank you for answering my question, in fact I don’t have deep knowledge about relational dbs, just very little. It’s great that couchdb just store and sync among cluster nodes the changed part of a document, not the whole document, thanks. About the second question, I think it might be impossible to create a separate database for each user if we have thousands of users for a website, and it also might not be a good solution to split some data into separate databases according to its owner, like articles created by users, generally, we keep all the articles in the same database. So does it mean that I shouldn’t use the _users database to keep users info? Thanks & regards, Jinmin ________________________________ From: Harald Kisch <haraldki...@gmail.com> Sent: Thursday, April 26, 2018 4:45:29 PM To: user@couchdb.apache.org Subject: Re: 答复: Some questions about couchdb Hi Jinmin, as Bill answered already. Maybe there are two things worth to mention: First: In 1 and 3 of your questions only the difference between the document changes are stored to disk, not the whole document. Second: Regular Knowledge of relational databases will not help you with schemaless approaches of NoSQL Databases. In my experience so far, there are a lot of confusing misunderstandings if you compare both approaches. If you already have some deep Knowledge about relational databases, it would be helpful for you to keep in mind, that at least CouchDB is not only another way to store data. Harry On Thu, Apr 26, 2018 at 8:38 AM, Martin Broerse <martin.broe...@gmail.com> wrote: > Perhaps also take a look at the https://bloggr.exmer.com exampe to see > CouchDB & PouchDB in action (https://github.com/broerse/ember-cli-blog) > > On Thu, Apr 26, 2018 at 4:26 AM, 明 淨 <jinmin...@outlook.com> wrote: > > > > > > > Thank you, I will check Pouchdb. > > > > > > > > > > > > ________________________________ > > From: Bill Stephenson <b...@cherrypc.com> > > Sent: Thursday, April 26, 2018 9:37:42 AM > > To: user@couchdb.apache.org > > Subject: Re: Some questions about couchdb > > > > Hi Jinmin, > > > > > On Apr 25, 2018, at 7:11 PM, 明 淨 <jinmin...@outlook.com> wrote: > > > > > > What I'm thinking about is the following things: > > > > > > 1. If I store the info of a person as a document in couchdb, will > update > > of a few words in his/her self introduction cause the whole document to > be > > rewrite? also, I have to submit the whole document to make this a few > words > > update? Shall couchdb support field unit update in the future? > > > > In a nutshell yes, you will update the entire document but that’s easy. > > You “get” the document as a JSON object and then update just the parts of > > the object you want and then “put” the updated document object back in > the > > database. > > > > > > > > 2. By default, a user of a database in couchdb can update all the > > documents in the database, but usually in the real world, every document > > has it's owner, and shouldn't be updated by users other than the owner. > Is > > there any mechanism in couchdb to support document unit authorization? > > > > With CouchDB you can set it up so every user has their own database that > > only they can create, modify, and delete documents in. You can assign > other > > users “roles” and add them to a database's “Permissions” that allow them > to > > only read documents in a database as well. > > > > > > > > 3. As replication is the basis of data sync across cluster nodes, so > > will couchdb support field unit update in cluster data sync, not just > > document unit? > > > > I don’t know the answer to this, but I do know you can replicate and sync > > databases between more than one CouchDB server. You don’t need a cluster > to > > do that though. > > > > I will suggest you take a look at PouchDB too. The info on their site > will > > help you get a feel for some of the ways you can manage users and > documents > > and permissions and you can use PouchDB in your web browser offline > without > > a CouchDB server, and you can sync your web browser database with a > remote > > CouchDB server, or just use PouchDB with a remote CouchDB server. > > > > https://pouchdb.com > > > > Also check out their “Authentication” plugin page to learn more about how > > you can manage users and database permissions on your CouchDB: > > > > https://github.com/pouchdb-community/pouchdb-authentication/blob/master/ > > docs/recipes.md > > > > I hope this helps, > > > > Bill > > > -- -- Dipl.-Inf. Harald R. Kisch Falkenstraße 19C 81541 München Germany Mobil DE: +49 (0) 176 56 58 58 38 Skype: harald.kisch Mail: haraldki...@gmail.com
