In Apache Hive, there are two ways to delete a table: truncating and dropping the table. Here’s an overview of each method:
- Truncating a table: When you truncate a table in Hive, all the data in the table is deleted, but the table metadata and structure remain intact. Truncating a table is a faster operation than dropping a table because it doesn’t involve deleting and recreating the table. However, truncating a table cannot be undone, and the deleted data cannot be recovered.
To truncate a table in Hive, you can use the following command:
TRUNCATE TABLE table_name;
Dropping a table: When you drop a table in Hive, both the table metadata and the data stored in the table are deleted permanently. Dropping a table is a slower operation than truncating a table because it involves deleting the table and all its associated data from the filesystem. However, dropping a table frees up storage space and removes all the metadata associated with the table, including any indexes, statistics, and partitions.
To drop a table in Hive, you can use the following command:
DROP TABLE table_name;
It’s important to note that dropping a table in Hive cannot be undone, and all the data stored in the table will be lost permanently. Therefore, it’s a good practice to take a backup of the data before dropping the table, especially if the data is valuable or irreplaceable.