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Frequently Asked Basic PostgreSQL Interview Questions and Answers PostgreSQL is the widely used open source database. If you are preparing for PostgreSQL interview, following list of basic PostgreSQL interview questions and answers might help you in your interview preparation. Following PostgreSQL interview questions and answers cover PostgreSQL basic concepts like feature and advantages of PostgreSQL, key difference between MySQL and PostgreSQL, basic PostgreSQL database administration commands and tools, general PostgreSQL database concepts like Stored Procedures, Functions, Triggers, Cursor, Index, Joins, Subqueries etc.  1. What is PostgreSQL? What do you know about PostgreSQL? PostgreSQL, often simply "Postgres", is an open-source object-relational database management system (ORDBMS) with an emphasis on extensibility and standards-compliance. It is released under the PostgreSQL License, a free/open source software license, similar to the MIT License. PostgreSQL is develo...

16 PostgreSQL Database Administration Commands Following are basic PostgreSQL database administration commands which each PostgreSQL database administrator should know. These PostgreSQL database administration commands include creating users in PostgreSQL, setting up user credentials in PostgreSQL, change / update PostgreSQL user password, check whether PostgreSQL is up and running, commands to create, delete, drop, start, stop, restart, backup, restore PostgreSQL database, getting the list of all databases in PostgreSQL, finding out what version of PostgreSQL is running, PostgreSQL help and history commands, commands to get the list of all the tables in a PostgreSQL database, commands to turn on timing and checking how much time a query takes to execute, commands to see the list of available functions in PostgreSQL etc. Lets have a look on following PostgreSQL Database Administration Commands. 1. How to change PostgreSQL root user password? $ /usr/local/pgsql/bin/psql postgres postgre...

MongoDB vs Cassandra: Difference and Similarities between MongoDB and Cassandra MongoDB and Cassandra have occupied a very big market of NoSQL Schema-Free databases. So, before going to choose any one of them, it is logical to compare basic features of both MongoDB and Cassandra. MongoDB and Cassandra both are fully-featured NoSQL databases and choosing one of them heavily depends upon your application requirements. There are a lot of similarities and differences between MongoDB and Cassandra. Following is the basic comparison of MongoDB and Cassandra in terms of data storage model, usage etc. Differences between MongoDB and Cassandra 1. MongoDB has a document-oriented data model while Cassandra has column-oriented data model and storage type.  MongoDB acts much like a relational database. Its data model consists of a database at the top level, then collections which are like tables in MySQL (for example) and then documents which are contained within the collection, like rows in M...

Types and Examples of NoSQL Databases NoSQL databases are growing with very rapid speed because of their exciting features like more flexibility and scalability, schema-free architecture, easy replication support, simple API, consistent / BASE (not ACID), support for big data and more. Key-Values Stores, Column Family Stores, Document Databases, Graph Databases are the types of NoSQL Databases. MongoDB, CouchDB, CouchBase, Cassandra, HBase, Redis, Riak, Neo4J are the popular NoSQL databases. MongoDB, CouchDB, CouchBase are document-oriented NoSQL databases, Redis and Riak are key-value stores, Cassandra and HBase are column family stores and Neo4J is a graph database. Lets discuss these types of databases in detail. 1. Key-Values Stores The main idea here is using a hash table where there is a unique key and a pointer to a particular item of data. The Key/Value model is the simplest and easiest to implement. But it is inefficient when you are only interested in querying or updating par...

28 MongoDB NoSQL Database Interview Questions and Answers MongoDB is the best free open source NoSQL document oriented database. If you are preparing for the technical interview on MongoDB NoSQL database, must prepare the following MongoDB NoSQL database interview questions. These MongoDB NoSQL database interview questions cover basic concepts of NoSQL databases, Replication, Sharding, Transactions and Locking, Profiler, Nuances, Journalling features etc. Lets have a look on following MongoDB NoSQL database interview questions: 1. What do you mean by NoSQL databases? What is the difference between NoSQL and RDBMS? Why and why not to use NoSQL databases? What are the various advantages of NoSQL databases? I have written a complete blog post to answer above questions here . 2. What are the various types of NoSQL databases? Types of NoSQL Databases Examples: MongoDB, Cassandra, CouchDB, Hypertable, Redis, Riak, Neo4j, HBASE, Couchbase, MemcacheDB, RevenDB and Voldemort are the examples o...

CouchDB vs CouchBase: Differences and Similarities between CouchDB and CouchBase Apache CouchDB and CouchBase, both are Free, Open Source, NoSQL document databases using JSON as their document format. Apache CouchDB and CouchBase have a lot of similarities and differences. Basically CouchBase is made up by combining the features of CouchDB and MemBase databases. CouchDB's document-oriented data model, indexing and querying capabilities are combined with MemBase's distributed key-value data model, high performance, easily scalable, always-on capabilities are combined to form CouchBase.  In short, we can say: CouchBase = CouchDB + MemBase But, CouchBase is not a new version of CouchDB but it is in fact a new version of MemBase. CouchBase Server is actually a new name for the MemBase Server. CouchBase is  not a drop-in replacement for CouchDB but is a drop-in replacement for Memcached.  CouchBase  still uses the Memcached protocol and not the RESTful API of CouchDB. Mea...

12 Best Free and Open Source NoSQL Databases NoSQL databases are becoming popular day by day. I have come up with the list of best, free and open source NoSQL databases. MongoDB tops the list of Open Source NoSQL databases. This list of free and open source databases comprises of MongoDB, Cassandra, CouchDB, Hypertable, Redis, Riak, Neo4j, HBASE, Couchbase, MemcacheDB, RevenDB and Voldemort. These free and open source NoSQL databases are really highly scale-able, flexible and good for big data storage and processing. These open source NoSQL databases are far ahead in terms of performance as compared to traditional relational databases. However, these may not be always the best choice for you. Most of common applications can still be developed using traditional relational databases. NoSQL databases are still not the best option for a mission critical transaction needs. I have listed down a small description of all these best free and oper source NoSQL databases. Lets have a lo...

NoSQL vs RDBMS: Why and why not to use NoSQL over RDBMS?  NoSQL (not only SQL) is not a relational database management system (RDBMS).  We will discuss what is the difference between NoSQL databases and Relational Databases and then why and why not to use NoSQL database model over traditional and relational database model (RDBMS) in detail. As NoSQL is the new technology, it is also facing many challenges, so will also have a look upon them. Today, the internet world has billions of users. Big Data, Big Users, and Cloud Computing are the big technologies which every major internet application is using or preparing to use because internet application users are growing day by day and data is becoming more and more complex and unstructured which is very hard to manage using traditional relational database management system (RDBMS). NoSQL technology has the answer to all these problems. NoSQL is meant for Unstructured Big Data and Cloud Computing. A NoSQL datab...