Doubt in word count query

Question

What is meant by count(1) n the below code snippet:

select word,count(1) as count from
(SELECT explode(split(sentence, " ")) AS word FROM texttable)tempTable
group by word

Answer 1

The COUNT function returns the number of rows for which the expression evaluates to a non-null value. 

Since the expression "1" evaluates to non-null for every row, and since you are not removing duplicates, COUNT(1) should always return the same number as COUNT(*).