What is the usage of the explode function in Hive?

In Hive, the explode function is used to split an array or map type column into multiple rows of data. For example, if a column contains an array, the explode function can break down each element of this array into a separate row of data.

For example, suppose there is a table t that contains an array column named col. You can use the explode function to split this array column into multiple rows of data, as shown below:

SELECT explode(col) FROM t;

This will return a result set containing rows with each element from an array column. The explode function can also be used to split columns of map type, separating the key-value pairs in the map into two separate columns, one for the key and one for the value.

In general, the explode function in Hive is used to split array or map type columns into multiple rows of data, making it easier for data processing and analysis.