Summary of IMS database types and functions
The following table provides a summary of characteristics, functions, and options of the different types of IMS™ databases.
| Characteristic | HSAM | HISAM | HDAM | PHDAM | HIDAM | PHIDAM | DEDB | MSDB |
|---|---|---|---|---|---|---|---|---|
| Hierarchical structures | Y | Y | Y | Y | Y | Y | Y | N |
| Direct access storage | Y | Y | Y | Y | Y | Y | Y | N |
| Multiple data set groups | N | N | Y | Y | Y | Y | N | N |
| Logical relationships | N | Y | Y | Y | Y | Y | N | N |
| Variable-length segments | N | Y | Y | Y | Y | Y | Y | N |
| Segment Edit/Compression | N | Y | Y | Y | Y | Y | Y | N |
| Data Capture exit routines | N | Y | Y | Y | Y | Y | Y | N |
| Field-level sensitivity | Y | Y | Y | Y | Y | Y | N | N |
| Primary index | N | Y | N | N | Y | Y | N | N |
| Secondary index | N | Y | Y | Y | Y | Y | Y | N |
| Logging, recovery, offline reorganization | N | Y | Y | Y | Y | Y | Y | Y |
| VSAM | N | Y | Y | Y | Y | Y | Y | N/A |
| OSAM | N | N | Y | Y | Y | Y | N | N/A |
| QSAM/BSAM | Y | N | N | N | N | N | N | N/A |
| Boolean operators | Y | Y | Y | Y | Y | Y | Y | N |
| Command codes | Y | Y | Y | Y | Y | Y | Y | N |
| Subset pointers | N | N | N | N | N | N | Y | N |
| Uses main storage | N | N | N | N | N | N | N | Y |
| High parallelism (field call) | N | N | N | N | N | N | N | Y |
| Compaction | Y | Y | Y | Y | Y | Y | Y | N |
| DBRC support | Y | Y | Y | Required | Y | Required1 | Y | N/A |
| Partitioning support | N | N | N | Y | N | Y | Y | N |
| Data sharing | Y | Y | Y | Y | Y | Y | Y | N |
| Partition sharing | N | N | N | Y | N | Y | Y | N |
| Block level sharing | Y | Y | Y | Y | Y | Y | Y | N |
| Area sharing | N/A | N/A | N/A | N/A | N/A | N/A | Y | N/A |
| Record deactivation | N | N | N | N | N | N | Y | N/A |
| Database size | med | med | med | lg | med | lg | lg | sml |
| Online utilities | N | N | N | N | N | N | Y | N |
| Online reorganization | N | N | N | Y | N | Y | Y | N |
| Batch | Y | Y | Y | Y | Y | Y | N | N |
Table notes:
- The IMS catalog is a PHIDAM database. Unlike other HALDB databases, the IMS catalog PHIDAM database does not require DBRC support. However, DBRC support is strongly recommended outside of test and development environments.