Hive coalesce vs nvl: Key Differences Explained

In Hive, coalesce and nvl are both functions used to handle NULL values, but they have some differences.

1. The coalesce function can take multiple arguments and returns the first non-NULL value from the list. For example, coalesce(null, 1, 2) will return 1, since 1 is the first non-NULL value. On the other hand, the nvl function can only accept two arguments and will return the second parameter if the first one is NULL. For instance, nvl(null, 1) will return 1.
2. The coalesce function is more convenient when dealing with multiple arguments, as it can handle multiple potentially NULL values at once, while the NVL function can only handle two arguments.
3. In Hive, the coalesce function is a standard SQL function, while the nvl function is a unique function in Oracle. Although Hive also supports the nvl function, there may be compatibility issues when porting to other databases, so it is recommended to use the coalesce function.