In PostgreSQL, log10() is a mathematical function that returns the base 10 logarithm of its argument.
It was added in PostgreSQL 12 as a SQL-standard equivalent of the existing log() function.
There is a difference between the two functions though, because log() allows us to specify which base to use (although it defaults to base 10), whereas log10() uses base 10 only.
In PostgreSQL, we can use the trim_scale() function to remove any trailing zeros from the end of the fractional part.
This doesn’t change the value, it merely reduces the number characters whenever there are unnecessary zeros on the end.
In PostgreSQL, min_scale() is a mathematical function that returns the minimum scale needed to represent the supplied value precisely.
The “scale” is the number of fractional decimal digits. For example, a value of 1.9500 has a minimum scale of 2, whereas 1.957 has a minimum scale of 3.
We pass the value to the function as a numeric argument, and it returns the result as an integer.
In PostgreSQL, we can use the reverse() function to return a specified string with its characters reversed. In other words, the string is returned with its characters in the reverse order to how we provided them.
In PostgreSQL, the regexp_matches() function returns substrings that match a given POSIX regular expression in a given string. We can specify that all matches are returned or just the first match. If all matches are returned, each is returned in a separate row.
We pass the string as the first argument and the pattern as the second argument. We can also provide a flag as an optional third argument, which determines how the function behaves.
Each returned row is a text array containing the whole matched substring or the substrings matching parenthesised subexpressions of the pattern.
In PostgreSQL, the regexp_match() function returns a text array containing substrings that match a given POSIX regular expression in a given string. Only the first match is returned (to return all matches, use regexp_matches() instead).
We pass the string as the first argument and the pattern as the second argument. We can also provide a flag as an optional third argument, which determines how the function behaves.
PostgreSQL has a pg_input_error_info() function that allows us to see the error details that would be returned if we were to pass an invalid value for the specified data type.
Basically it tests whether the given string is valid input for the specified data type. If invalid, it returns the details of the error that would have been thrown. If valid, the result is null.
In PostgreSQL, the pg_input_is_valid() function tests whether the given string is valid input for the specified data type.
It returns a boolean value of either true or false.
This function only works if the data type’s input function has been updated to report invalid input as a “soft” error.
In PostgreSQL we can use the array_replace() function to replace a specified element (or elements) in an array with another element.
The first argument is the array, the second is the element to replace, and the third is the element to replace it with.
In PostgreSQL, we can use the regexp_substr() function to return a substring from a string based on a POSIX regular expression.
We can get the first occurrence or any other subsequent occurrence that matches the expression.