I previously explained that Postgres allows multiple databases per cluster. The outstanding question might be, when should I use multiple clusters, multiple databases, or multiple schemas? The following table outlines the advantages of the various container types:
| Feature | Cluster | Database | Schema |
| Isolated Server Start/Stop | ✓ | ||
| Connection Control | ✓ | ✓ | |
| Private System Tables | ✓ | ✓ | |
| Private Plug-Ins | ✓ | ✓ | |
| Isolated Administration | ✓ | ||
| Shared Administration | ✓ | ✓ | |
| Isolated Resource Usage | ✓ | ||
| Shared Resource Usage(1) | ✓ | ✓ | |
| Data Isolation(2) | ✓ | ✓ | |
| Cross-Container Queries | ✓ |
(1) A large number of data containers increases the usefulness of resource sharing, e.g. shared_buffers.