I am trying to access one database collection in a different database. Is it possible in arangodb.
Regards,
Sajeev
No, its not possible.
ArangoDB strictly separates databases, so AQL doesn't know about databases in first place, its concept is below the database layer.
As we also discussed in the github issue we actually don't intend to implement support for this.
Related
How do you perform queries without specifying shard key in mongodb api and how do you query across partitions?
In sql api the latter is enabled by setting EnableCrossPartitionQuery to true on the request but I'm not able to find anything like that for the mongodb api. And my queries that work on an unsharded collection now fails(queries that specify the shard key works as expected).
The queries fail indiscriminately of whether I use the AsQueryable extension syntax or the aggregation framework.
As I know, no such property similar to EnableCrossPartitionQuery in CosmosDB Mongo API. In fact, CosmosDB is an independent server implementation that does not directly align with MongoDB server versions and features.
CosmosDB supports a subset of the MongoDB API and translates requests into the CosmosDB SQL equivalent. CosmosDB has some different behaviours and results, particularly with their implementation of partitioning as compared to MongoDB's sharding. But the onus is on CosmosDB to improve their emulation of MongoDB.
Certainly, you could add feedback here to get official assistance or consider using MongoDB Atlas on Azure if you'd like full MongoDB feature support.
Hope it helps you.
Was confirmed a bug by the Product Group team! Will be fixed in first two weeks of september in case anyone runs into the same problems in the mean time.
I'm quite new to CouchDB... let say that I have a multiple databases in my CouchDB, one per user, each of db have a one config document. I need to add a property to that document across all dbs. Is it possible to update that config document in all databases (not doing it one by one)? if yes what is the best way to achieve this?
If I'm reading your question correctly, you should be able to update the document in one database, and then use filtered replication to update the other databases (though you can't have modified the document in those other databases, otherwise you'll get a conflict).
Whether it makes sense for the specific use case, depends. If it's just a setting shared by all users, I'd probably create a shared settings database instead.
I do not think that is possible, and I don't think that is the intended use for CouchDB. Even if you have everything in a single database it's not possible to do it in a quick way (there is no equivalent to a SQL update/where statement).
I'm currently involved in a app project, and I'm incharge of setting up the backend.
What i'm use to using is a MYSQL database + php for cleaning and managing the data sent to and fro the front end, which I have much more experience in. However, because of certain preferences of my bosses, on this project I've found myself looking at IBMs Bluemix and Cloudant software. Cloudant is a NoSQL database(like CouchDB) and my experience regarding noSQL is severely lacking. All I've mananged to do so far is to create a few JSON documents, and some basic views
What I need to figure out is how to perform the CRUD(create,read,update,delete) actions on a NoSQL database, or at least what it would look like.
In addition to this, I need to know if there are ways to implement security measures(implement security and anti-hacking functions) on a NoSQL database without an external source, or will I need to learn how to reroute the data through some sort of php function first, if i want it cleaned, before sending it to the Cloudant server where my database sits.
Let me know if my attempt to explain my problem is lacking in clarity. I'll try my best to state a different way, if need be.
Generally speaking, there is nothing equivalent to an ANSI to NoSQL databases. In other words, NoSQL databases are not as standardized as SQL databases. All standards are starting to appear. You can think of it as a technology still in the making.
What you have in general is an API with methods such as put_record or delete_record, or a REST interface that is logically equivalent. Also, in general you CRUD the whole record, not parts of the record.
Take a look at the reference: Cloudant - Reading and Writing
Having that said, in your case I would recommend abstracting away from the specific implementation of the NoSQL you want to use if you care about avoiding vendor lock-in. So I would suggest you to wrap CRUD functions using PHP functions that later can be replaced if you want to change the NoSQL database flavor.
This approach has the additional advantage to provide an abstraction for you to implement your own security. Some important NoSQL databases have no concept of multi-tenancy or just implemented that. Again, it is a technology in the making.
When your mindset is the relational one, you tend to think of the database as something that will help you guarantee data consistency as much as possible. But NoSQL databases are not like that. Think of them as a simple repository of documents (in a JSON or XML structure, for instance), without cross references.
Then the obvious question is perhaps: why would anyone want such a thing? One of the possible answers is because NoSQL databases may hold an aggregate of consolidated data. You can then retrieve aggregates to save time reprocessing or re-retrieving data unnecessarily.
As for security, most (if no all) NoSQL databases have some pretty good authentication mechanisms.
I've been able to sync data from my cloudant instance to my nodejs based pouchdb, however I need to setup a secondary search index and therefore I created a view on the couchdb instance however I am unable to see it in my synced pouchdb instance.
I see it in cloudant, in all documents, however after syncing and calling alldocs on pouchdb, it's not there. Also, i'm using the pouchdb-find plugin and I can't reference the secondary index search fields. Of course from pouchdb if if set the secondary index, it works fine.
Am I missing something? Does sync not replicate design docs in PouchDB? If not, what's the best way to create a persistent secondary index?
Any good docs for this? (Nolan....?) Speaking of docs, or support, is there an IRC room or some other live support for couchdb from the user community?
Thanks for your attention,
Paul
pouchdb-find is a reimplementation of Cloudant Query Language, not their search index (which is what I think you're talking about). It's also not done; I've only written about half of the operators. :) You may also want to try the pouchdb-quick-search plugin, which is for full-text search.
In general, the advice I usually give people is to not sync design documents at all – just replicate using a filter to avoid syncing design docs. Then you can create design documents that are optimized for whatever platform you happen to be on (PouchDB, CouchDB, Cloudant, the various PouchDB plugins, etc.).
And yeah, we are usually pretty responsive inside of the IRC channel and on the mailing list, but it's a small operation because we aren't sponsored by Cloudant or Couchbase or anybody. The core PouchDB team are all hobbyists. :)
Maybe this is stupid but, does the user that access couch has the admin role? Only admins can see and edit design documents.
I have a User database that houses all of the user information plus permissions to applications, etc. If I have a general database as described and then other databases for each Web Application, can I link up databases to make Relationships between the two databases using Fluent API or Code First? There are not so elegant ways to do this, but I wanted to ask the question first before getting involved with a custom solution.
For example: 1 DbContext, DbSets for each table in the 2 databases. Ability to relate entities between databases with Fluent API.
Thanks in advance.
The answer is no. The context is related to a single database. There is even no easy way to hack this because the context still can create queries only for a single database so if you want to have access to multiple databases you need either a context for each database (no cross context queries or relations exists) or you need to expose all tables from other databases as views or aliases in the database used by the context.