couchdb

问题 I'm looking for a common data access framework that will provide portability across various nosql databases like SimpleDB, Azure Tables, Cassandra, CouchDB, MongoDb, etc. I'm building an app and would like my customers to be able to use which ever nosql store they want. In a more relational scenario, I'd use Linq over nHibernate or Entity Framework, but I haven't found an equivalent framework for nosql databases. All I've found is database specific API's even though there seem to be

问题 I have been reading and learning about NoSQL and MongoDB, CouchDB, etc, for the last two days, but I still can't tell if this is the right kind of storage for me. What worries me is the eventual consistency thing. Does that type of consistency only kick in when using clusters? (I'm hosting my sites in a single dedicated server, so I don't know if I can benefit from NoSQL) For which kind of applications is OK to have eventual consistency (instead of ACID), and for which ones it isn't? Can you

问题 I am implementing a filter feature for my application and having trouble with writing the view on CouchDB. While in SQL, this would be a statement with multiple join. How to replace multiple join in CouchDB. This article covers single join: http://www.cmlenz.net/archives/2007/10/couchdb-joins. However, it's not obvious to me how to extend this approach to multiple join. Imagine my object has a dozen properties and each property can have its individual filter. For simplicity, let's assume it

问题 I'm new to CouchDB and have a question. I'm saving messages with the ID of the parent message as an attribute. A message can also have a childMessage as parent, so it looks like a tree. How can i query all childs including the childs of the childs? Thank you 回答1: This is the commonly used method when dealing with hierarchical data: http://probablyprogramming.com/2008/07/04/storing-hierarchical-data-in-couchdb/ 回答2: CouchDB works best with the de-normalized data. You should consider de

问题 I'm currently playing a bit with couchdb. I'm trying to migrate some blog data from redis (key value store) to couchdb (key value store). Seeing as I probably migrated this data a gazillion times from and to different blogging engines (everybody has got to have a hobby :) ), there seem to be some encoding snafus. I'm using CouchREST to access CouchDB from ruby and I'm getting this: <JSON::GeneratorError: source sequence is illegal/malformed> the problem seems to be the body_html part of the

问题 What are the major differences between MongoDB and CouchDB, and are there any other major NO-SQL database-servers out there worth mentioning? I know that CERN uses CouchDB somewhere in their LHC back-end; huge stamp of approval. What are MongoDB - and any other major servers' - references? Update One of the major selling points of CouchDB, to me, is the REST-based API and seamless JavaScript integration using JSON as a data-wrapper. Is this possible with any of the other NO-SQL databases

问题 What are the major differences between MongoDB and CouchDB, and are there any other major NO-SQL database-servers out there worth mentioning? I know that CERN uses CouchDB somewhere in their LHC back-end; huge stamp of approval. What are MongoDB - and any other major servers' - references? Update One of the major selling points of CouchDB, to me, is the REST-based API and seamless JavaScript integration using JSON as a data-wrapper. Is this possible with any of the other NO-SQL databases

问题 I've been toying around with Map Reduce with CouchDB. Some of the examples show some possibly heavy logic within the map reduce functions. In one particular case, they were performing for loops within map. Is map reduce run on every single possible document before it emits your selected documents? If so, I would think that means that running any kind of iterative processing within the map reduce functions would increase processing burden by an order of magnitude, at least. Basically it boils

问题 I've been toying around with Map Reduce with CouchDB. Some of the examples show some possibly heavy logic within the map reduce functions. In one particular case, they were performing for loops within map. Is map reduce run on every single possible document before it emits your selected documents? If so, I would think that means that running any kind of iterative processing within the map reduce functions would increase processing burden by an order of magnitude, at least. Basically it boils

问题 The way of resolving replication conflicts recommended by official documentation is: Read conflicting revisions using document's _conflicts field (e.g. via a view) Fetch docs for all revisions listed Perform application-specific merging Remove unwanted revisions The problem comes in when I want to merge deleted documents. They do not show up in _conflicts field, but in _deleted_conflicts . If I merge only using _conflicts field, and a document is deleted in the local database and edited in