Most Frequently Asked CouchDB Interview Questions
The couch is an acronym for Cluster Of Unreliable Commodity Hardware and DB for the database. CouchDB is an open source software. Its a complete focus is on the ease of use and embracing the web.CouchDB has a No SQL document-oriented database architecture. CouchDB is written in Erlang language.
Why is CouchDB used?
- CouchDB assists the users with useful data mapping which allows filtering, combining and querying the information.
- CouchDB provides easy replication of the data, and as a result, data between the machines and databases can be copied, shared and synchronized.
- CouchDB can be directly used to write a client’s application.There is no need for another server and as a result, the development time is reduced.
- The filter feature of CouchDB supports to replicate the database of a particular user and CouchDB also supports in replicating the database of a client.
Some of the advantages of CouchDB are:-
- Multi-Version Concurrency Control (MVCC) Support
- Incremental Replication
- Partition Tolerance
- Browser Based GUI
- ACID Properties
This is a fundamental CouchDB interview question
|1.||Data is stored in documents in CouchDB||Data is stored in tables in RDBMS|
|2.||Replication is easy in CouchDB||Replication is difficult in RDBMS|
|1.||In CouchDB, the records are stored in the documents in the database.||In MongoDB, the records are stored in the collection in the database|
|2.||Master-Master replication in CouchDB||Master-Slave replication in MongoDB|
|3.||CouchDB is written in Erlang||MongoDB is written in C++|
|4.||In CouchDB, the interface is REST/HTTP||In MongoDB, the interface is TCP/IP Custom Protocol|
|5.||Slower than MongoDB||Faster than CouchDB|
|1.||In PouchDB Keys are ASCII ordered||CouchDB makes use of ICU to order the keys in a view query|
|2.||In the view results, the actual offset is not returned somewhat offset only mirrors the skip parameter||In the view results, CouchDB returns an offset property|
This is one of the most asked CouchDB interview questions.
- Stores the data in the JSON document.
- It does all the work such as data insertion, replication, etc. via HTTP, so it has a RESTful interface
- It can replicate to those devices that go offline and then take care of the data sync when they come online like Android Phones
- It assists the user in filtering out the data that a user wants to replicate to the different nodes.
- Unlimited amount of ‘masters’ can be used, i.e., in CouchDB, there is multi-master replication
CouchDBkit is a complete package which gives full-featured and easy client framework to the python applications to access and manage CouchDB. CouchDBkit assists in maintaining the databases, CouchDB server, view access, and doc management.
Point to be noted: Go through this Q&A very thoroughly as this is one of the essential CouchDB interview questions.
CouchDB makes the use of a model which is known as an ‘Optimistic Currency’ model. ‘Optimistic Currency’ model grants approval to send a document version with the CouchDB update. CouchDB scans the document version, and if the present document version does not tally with document version which was was sent, then CouchDB rejects the change in the release.
|1.||SQL stores the data by using RDBMS||CouchDB stores the data in the JSON document.|
|2.||SQL prefer an automatic transmission||CouchDB prefers a manual transmission|
|3.||SQL is written in C, C++||CouchDB is written in Erlang|
ETL represents Extracting, Transforming and Loading of the data from any of the systems to the destination. ETL includes 3 steps for the data integration process:
- Extracting: In the method of Extracting the data is first located and then the source file is removed.
- Transforming: In the process of Transforming the file is transported to the required target
- Loading: In the process of loading the data is charged in the target system in the appropriate format.
This is one of the favorite questions in CouchDB interview Questions.
The tools that are used in ETL ( Extracting, Transforming and Loading )are:-
- Cognos Decision Stream
- Oracle Warehouse Builder
- Business Objects XI
- SAS business warehouse
- SAS Enterprise ETL server
Fact is represented as a vital component of a multi-dimensional model which examine all the measures.
There are four types of Facts:-
- Addictive Facts
- Semi-addictive Facts
- Non-addictive Facts
- In Linux or Unix log files are located in /usr/local/var/log/CouchDB/couch.log . This log file location can be set in the default.ini file.default.ini file is located in /etc/CouchDB/path.
- If the user has installed from the source and the user is running the CouchDB in the dev mode, then the location of the log files will be:- YOUR_CouchDB_SOURCE_DIRECTORY/tmp/log/couch.log