![]() Search engine databases work similarly to document databases, the main difference is that the database will search all the text in the documents and create an index of the searchable terms. The most popular key-value databases: Neo4j, Giraph, RedisGraph. Use-cases could be a recommendation engine or a knowledge graph. That kind of database can be used when your data looks like a graph like in social networks. You can make queries by relationships which is difficult with the other kind of databases. Graph databases are about relationships between entities. ![]() The most popular key-value databases: Redis, Memcached. Good examples of use could be: caching or pub/sub. If you need fast access to data, and no complex querying, key-value databases are a good option. Unfortunately, it makes them limited in space since the memory space is smaller than the disk space. Since they run on memory instead of disk, they are also more expensive to run. Moreover, the use of unique keys makes it even quicker from its conception itself.Īs we can see key-value databases are very fast however, you need to be sure that their keys are unique. You do have a key that is associated with a value.īecause they are storing the data in the RAM instead of the disk, it allows key-value databases having fast access. Key-value databasesĪ key-value database is probably the easiest database to explain. The most popular columnar databases: Cassandra, HBase. Moreover, you can use a columnar database for your logs since you will most probably use a few columns for your queries. This makes it very efficient for column-based queries.Ī good use for a columnar database is data science where each column represents a feature. Columnar databasesĬolumnar databases also called wide-columnar databases, store records in columns rather than by rows, unlike SQL databases. The most popular document-oriented databases: MongoDB, CouchDB. Good use-cases for the document-oriented database are data analysis, mobile games, content management, and IoT This is really handy since it offers very good flexibility for the developers. Each document can have a different schema and contains different fields. That kind of database is storing documents that are JSON objects. In contrary to SQL databases, NoSQL databases don't expect a structured fixed schema for their records. ![]() Popular relational databases: MySQL, PostgreSQL. The primary keys allow you to perform joins between multiple tables to access all required data. One more important point about relational databases is that they do support SQL-like language. The relational databases are following a fixed schema for each record, and they need to stick to it. As well, the users' id inside the merchants' database as id. ![]() You will find the country_code of users as code inside the countries database. In the diagram above, the database merchants and countries relate to the users' database. Durability: guarantees that transactions that have been committed will survive permanently.Isolation: determines how transaction integrity is visible to other users and systems.Consistency: the data written to the database must be valid according to all defined rules.Atomicity: the database's operations either all occur, or nothing occurs.Relational databases support ACID transactions (atomicity, consistency, isolation, and durability). Each table relates to each other and each of their rows represents a record identified by a primary key. Relational databases (SQL)Ī relational database is a database where the information is organized in tables (two-dimensional arrays). You need to know that there are two types of databases: SQL databases (relational) and NoSQL databases. Is this project only a proof of concept?.Is performance something important in this project?.Before you do go that route, you might consider a few things: For your next project, you might choose the same database you are used to working with, and this might be totally fine.
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