SQL vs NoSQL

-


  • SQL databases are primarily called as Relational Databases (RDBMS). NoSQL databases are primarily called as non-relational, aggregate oriented or distributed databases.
  • SQL databases represent data in form of a table. NoSQL databases represent data in a collection of documents, key-value pairs, graph or wide-column stores.
  • SQL databases are vertically scalable ( scaled by increasing the horse-power of the hardware such as CPU, RAM, SSD etc...). NoSQL databases are horizontally scalable (scaled by increasing the no of database servers).

  • In SQL databases, ACID (Atomicity, Consistency, Isolation and Durability)  is supported. In NoSQL databases, atomicity is only supported with the content of a single aggregate and ACID is not supported when updating across multiple aggregates. NoSQL database follows the  CAP theorem ( Consistency, Availability and Partition tolerance )



Comments

Post a Comment

Popular posts from this blog

Constraints

-
Image
Constraints protect the database from errors. It puts restrictions on database state. Types of Constraints in Relational Model Domain Constraint Key Constraint Entity Integrity Constraint Referential Integrity Constraint  Types of Constraints that cannot be captured in relational model Semantic Constraints (Business Rules)                        eg : Buy one get one free Domain Constraint Value of each attribute in a tuple must be atomic (no repeating values) and consistent with its domain(data type). It could be null if allowed. Key Constraint key constraint specifies that the values in the column declared as a primary key must be unique. Types of keys Candidate Key            A relation has several keys referred to as candidate keys.but one candidate key is unique. it is               called the prima...
Read more

Normalization

-
Image
Normalization is a process for evaluating and correcting table structures to minimize data redundancies, thereby reducing the likelihood of data anomalies. Normalization starts by identifying the dependencies of a given relation and progressively breaking up the relation (table) into a set of new relations (tables) based on the identified dependencies. Normal Forms 0NF            Multi-valued attributes exists 1NF           Any multi-valued attributes (repeating groups) have been removed. 2NF           Any partial functional dependencies have been removed 3NF           Any transitive dependencies have been removed BCNF           Any anomalies resulting from functional dependencies have been removed 4NF           Any multi valued dependencies have been removed 5NF         ...
Read more

Entity Relationship Diagram (Pat II)

-
Image
Mapping Binary Relationships One to one Relationship  Partial participation (Partial participation is represented by single lines.)           Not every professor teaches every student. Every student is not learnt by every professor.             Relational Mapping                                                                   Professor ( Name , Phone , Address )                                                                                       ↑FK            Course   ( CourseId  , ...
Read more