Postgre SQL
PostgreSQL is a very powerful and open source object-relational database system. It is known for very strong reliability, data integrity, and accuracy.This is known to run on all major operating systems which includes Linux, UNIX and Windows.

  PostgreSQL manages multiple computations, through a system known as (MVCC).Here each transaction, allows changes to be made without hampering other transactions until and unless other changes are made. It completely eliminates the need for read locks ensuring the database maintains the atomicity, consistency, isolation, durability. PostgreSQL offers three levels of transaction which is :Read Committed, Repeatable Read and Serializable. PostgreSQL supports full serializability.

PostgreSQL includes the built-in synchronous replication. The durability of the transaction whether it is asynchronous or synchronous can be specified as per the database. This can be made per-user, per-session or even per-transaction. This is useful for the workloads where there are not many guarantees.

In PostgreSQL, the schema holds all the objects exception of roles and tablespaces. Schemas effectively act like the namespaces, which allows objects of the same name for co-existing in the same database. The newly created databases have a schema which is called "public".Here the public schema is not mandatory.
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