Postgres and Open Source Experts

In PostgreSQL, the CURRENT_DATE function is used to fetch the current date. To get the current date minus 1 day, we must subtract “1” from the CURRENT_DATE

In PostgreSQL, built-in functions like pg_database_size(), and pg_relation_size() are used to get the database and table size respectively.

PostgreSQL offers multiple functions to get the current date and time with or without the time zone, such as NOW(), CURRENT_TIMESTAMP, LOCALTIMESTAMP, etc.

PostgreSQL provides two wildcards: percent % and underscore _ that are used with the aid of the LIKE operator to perform pattern matching.

In PostgreSQL, the DATE_TRUNC() function trims unnecessary values from the date and time and returns a result with specific precision.

The REPLACE() is a very convenient function that is used to search and replace all the appearances of a string with a new substring/text.

In PostgreSQL, the LENGTH() function is used to find the length of a string. It takes a string as a parameter and returns the total number of characters.

PostgreSQL provides several ways to describe a table. For example, the “\d” command, “\dt” command, and information_schema.

In PostgreSQL, the DELETE statement is used with the collaboration of the WHERE clause and IN operator to delete multiple rows from a table.

In older versions of PostgreSQL, a B-tree index only contained pointers to the heap (table) of where a particular set of data could be accessed. This can cause performance issues because we first need to scan the index and then retrieve the data from the table. While Index scans are relatively cheap due to how they store data, table scans can be very expensive because the data can be at any place within the table. Though current enterprise methods of storage have alleviated much of this (SSD/NVME) performance impact, it still exists as we need to search for the data twice.