Postgres and Open Source Experts

In PostgreSQL, the log functions are used to find the logarithm of a particular number(provided in the function as a parameter). These functions include: log(), ln(), and log10().

In PostgreSQL, the extensions can be dropped by using the DROP EXTENSION statement which is followed by the name of the extension.

We can switch a user in PostgreSQL by simply executing the SET ROLE command. But the point to be noted is that we can only switch the user if it already exists.

The generated columns do not have a fixed value; rather this value is automatically computed by the expression that is determined at the time of column definition.

In PostgreSQL, the crosstab() function and the unnest() function are used to transpose columns into rows. These functions help us transform the table by returning the transposed table.

To get random rows from a database table, use the RANDOM() function with the ORDER BY clause. We can also specify the limit of the number of rows we want to fetch/retrieve.

The lcm() and gcd() functions take two numeric type parameters and return their lowest common factor and the greatest common divisor respectively.

To get the data between two specified date ranges, use the “WHERE” and “AND” clauses, the BETWEEN operator, the SYMMETRIC keyword, and the Range data types.

To find the size of the Postgres Tablespace, use the “pg_tablespace_size” function that takes the tablespace name as an argument and returns its size.

To find the average of a column we use the AVG() function taking the name of the column as a parameter. The ROUND() function rounds off a specified number up to particular decimal places.