Postgres and Open Source Experts

In Postgres, VACUUM is a command-line utility that vacates the space engaged by obsolete records, tuples, etc. It optimizes the performance of the Postgres databases, records, etc.

The MOD() function is one of the built-in mathematical functions in Postgres that perform the modulo operation on two numbers and retrieves the remainder.

PostgreSQL offers a convenient command named ANALYZE that collects the statistics about a database, table, or table’s columns for the query planner.

Introduction

One vital aspect of database administration is making copies of data and ensuring the replications remain in sync. With PostgreSQL there are two forms of native replication: physical replication, also known as binary replication, which sends changes at a disk block level and logical replication, which offers row-by-row changes streamed from a primary server to a secondary server. One of the major benefits of logical replication is …

In PostgreSQL, column aliases are temporary alternative names assigned to columns. The aliases are temporary alternatives, so they exist temporarily during the query’s execution.

PostgreSQL offers several built-in functions to find duplicate rows/records from a table, such as ROW_NUMBER() and COUNT().

PostgreSQL doesn’t support the ISNULL function. To achieve the functionality of the ISNULL function in Postgres, COALESCE function and CASE expressions are used.

NULLIF takes some arguments and returns a NULL value if both arguments are equal or if one of them is NULL, and it returns first argument if both arguments are not equal.

NOT EXISTS operator negates the working of the EXISTS operator. It returns TRUE if the subquery returns zero rows and FALSE if the subquery returns at least one row.

In Postgres, the EXISTS operator takes a subquery as an argument and checks the existence of a record in the subquery. Consequently, it returns true or false.