Internal Tables (Managed Tables)
Internal tables are managed by Hive, meaning Hive controls both the metadata and the underlying data files.
Characteristics:
- Hive manages the complete lifecycle of the table and its data
- Data is stored in Hive's warehouse directory (typically
/user/hive/warehouse/) - When you DROP the table, both metadata and data are deleted
- Hive has full control over the data location and format
External Tables
External tables are not managed by Hive - Hive only manages the metadata while the data remains in its original location.
Characteristics:
- Hive only manages table metadata, not the actual data
- Data can be stored anywhere in HDFS or other file systems
- When you DROP the table, only metadata is deleted, data remains intact
- Useful for sharing data with other systems or when data is managed externally
Key Differences Summary
| Aspect | Internal Table | External Table |
|---|---|---|
| Data Management | Managed by Hive | Managed externally |
| Data Location | Hive warehouse directory | Any HDFS location |
| DROP Behavior | Deletes both metadata and data | Deletes only metadata |
| Data Sharing | Difficult to share with other systems | Easy to share with other systems |
| Use Case | Hive-only data processing | Data shared across multiple systems |
| Performance | Slightly better (optimized location) | Depends on location and access patterns |
When to Use Each
Use Internal Tables when:
- Data is exclusively used by Hive
- You want Hive to manage the complete data lifecycle
- You need maximum performance optimization
- Data doesn't need to be shared with other systems
Use External Tables when:
- Data is shared with other systems (Spark, MapReduce, etc.)
- You want to preserve data when dropping tables
- Data is managed by external ETL processes
- You're working with existing data that shouldn't be moved
- You need to point to data in different locations or formats
External tables provide more flexibility and are commonly used in enterprise environments where data needs to be accessed by multiple tools and systems.
Top comments (0)