PostgreSQL is an open-source and free database management system. It emphasizes SQL compliance and extensibility. The original name of PostgreSQL was POSTGRES. The name is the successor to the Ingres database that was the product of the University of California. It got a new name, ‘PostgreSQL,’ that reflects the system’s support for SQL.
This DMS is one of the strongest database systems which extend SQL language with features that help to store and scale complex data jobs. Origins of this system date back to 1986, which is a part of the POSTGRES project. It has almost 30 years of development on the core platform.
It has a popular and great reputation for its reliability, architecture, data integrity, extensibility, robust feature set, and dedication to the open-source community. The software consistently delivers innovative solutions. This DMS can run on the major operating systems, and it has been ACID-compliant. It has strong add-ons like PostGIS and a geospatial database extender. It is an open-source relational database that many organizations and people select.
It has transactions with Consistency, Atomicity, Isolation, and Durability properties. It has automatically updatable views, triggers, materialized views, foreign keys as well as stored procedures. It handles different workloads, including single machines to data warehouses and web services with concurrent users. It is available for Linux, Windows, OpenBSD, and FreeBSD and is a default database for the macOS Server.
PostgreSQL has a built-in binary replication that ships the changes to replica nodes asynchronously. It can run read-only queries in contradiction of replicated nodes. This allows for the splitting of reading traffic efficiently among the many nodes.
It has a built-in synchronous replication which ensures for each write transaction; the master waits until one replica node has written data to the transaction log. Unlike the database systems, the durability of this synchronous or synchronous transaction can be easily specified per-database, per-session, per-user, and per-transaction. This is useful for workloads that don’t require guarantees. Not all data would need it as it reduces the performance due to the requirement of confirmation of the transaction that is reaching a synchronous standby.
Standby servers may be asynchronous or synchronous. The synchronous standby servers are specified in a configuration that determines the servers that are a candidate for synchronous replication.
PostgreSQL core does not include synchronous multi-master replication. Postgres-XC relates with PostgreSQL, and it provides synchronous and scalable multi-master replication. Related projects are Postgres-XL. Another fork is Postgres-R, an asynchronous multi-master replication system, i.e., Bidirectional replication. DMS uses it.
Many asynchronous replication packages are trigger-based. They are useful after the introduction of expanded core abilities. They are useful for situations where binary replication of database clusters is unsuitable.
PostgreSQL development has built-in support for the hash table and regular B-tree indexes. It has four index access methods: generalized inverted indexes, generalized search trees, Block Range Indexes, and Space-Partitioned. One can create user-defined index methods, but this is a highly involved process.
The schema in this system holds all the objects except tablespaces and roles. Schemas also act as namespaces; it allows objects of similar names to co-exist in a single database. This new databases’ schema is “public.” Any further schemas can fit in, and public schema is not mandatory.
Search_path is a setting that determines the order in which the DMS checks the schemas for any unqualified objects. It is set as $user, public by default. $user is the database user that is currently connected. The default can be set on a role level or a database. It is a session parameter, and you can change it freely, even during client sessions. It just affects one session.
Another data type is the domain, and it is the same as other data types. It has optional constraints that are defined by the domain creator. Thus, any data that enters into the column using a domain that will conform to whatever constraints were defined within the domain.
Procedural languages help the developers to extend their database with custom functions. These are stored procedures. The functions build the database triggers, custom data types, or aggregate functions. Procedural languages activate without crucial functions; it uses the DO command at the SQL level.
Languages are divided into various groups, which include procedures that are written in safe languages. They develop safely, and different users use them. Superusers create procedures that have unsafe languages. They allow bypassing of the database's security restrictions. It can access sources that are external to the database.
It has many features that help the developers in building applications. It also helps administrators to protect the integrity of the data. They build fault-tolerant environments, and users can manage this data even if the dataset is small or big. PostgreSQL is extensible apart from being free or open-source. Users can define their data types, build custom functions, and write code from various programming languages. This does not need the recompilation of the database.
PostgreSQL development conforms to SQL standards, and this conformance doesn’t contradict the traditional features. It could also lead to deprived architectural decisions. These features are mandatory for SQL standards and have the support of different functions or syntax. It moves towards conformance, and it can be expected over some time. PostgreSQL conforms to 170 out of 179 mandatory features for SQL: 2016. No relational database has met with full conformance to this standard.
Data type represents a data range easy to use. These are range types. There can be continuous or discrete ranges. Built-in range types are available, and this includes a huge range of integers, decimal numbers, dates, and time stamps.
It links to the other systems and helps to retrieve data using foreign data wrappers. They can take the form of a data source like a file system, web service, or relational database management system. Thus, the regular database queries use data sources like multiple data sources or regular tables.
PostgreSQL development is extensible, and its many features like indexes define APIs, which help to build out with PostgreSQL web applications. It is scalable in the quantity of data that is manageable. It can also accommodate a huge number of concurrent users. Many clients hire PostgreSQL developers to create strong web applications.