Connection path
Drivers, protocol expectations, endpoints, connection pools, and database tools.
ORACLE MIGRATION EVALUATION
Evaluate compatibility before you estimate the rewrite.
Halo documents Oracle-oriented behavior across protocol, data types, SQL semantics, PL/oraSQL, Package, dictionary views, and remote access. A migration evaluation shows what can remain, what needs configuration, and what still requires change.
Inventory what drives migration effort
Schema and data model
Types, sequences, constraints, indexes, partitions, temporary tables, and object naming.
SQL semantics
Functions, ROWNUM, joins, MINUS, MERGE, hierarchy, analytics, empty strings, and date behavior.
Procedural logic
PL/oraSQL blocks, routines, exceptions, cursors, dynamic SQL, Package APIs, and session state.
Administration and integration
Dictionary views, DBLINK, foreign access, error handling, jobs, reporting, and monitoring.
A four-stage evaluation
Map
Classify dependencies by protocol, schema, SQL, procedural logic, metadata, remote access, continuity, and operations.
Match
Identify documented Halo behavior, configuration requirements, and known boundaries for each dependency.
Validate
Run representative business transactions and operational scenarios in the intended mode and topology.
Decide
Record retained behavior, required configuration, necessary changes, and unresolved risks before setting the plan.
Oracle surfaces available for assessment
Types and data behavior
NUMBER and floating-point families; VARCHAR2 and NVARCHAR2; RAW and large objects; Boolean and date/time families; configurable Oracle-style DATE; and empty-string handling.
SQL behavior
ROWNUM, MINUS, DECODE, MERGE, Oracle outer joins, hierarchy, sequences, SYSDATE, DUAL, common table expressions, analytics, formatting, and selected output behavior.
PL/oraSQL and Package
Blocks, procedures, functions, exceptions, cursors, dynamic SQL, packages, types, variables, constants, and the documented system-package set.
Metadata and integration
Oracle-oriented dictionary views, synonyms, directories, DBLINK, query mapping, historical committed reads, recycle-bin metadata, and session- or transaction-scoped global temporary tables.
Turn rewrite pressure into test questions
| Potential pressure | Halo surface to assess | Evidence to capture |
|---|---|---|
| Changing connectivity | Oracle-compatible endpoint | Driver, pool, and tool results |
| Translating schema types | Oracle-oriented type families | Loaded values, precision, and dates |
| Rewriting SQL | Characteristic Oracle SQL and functions | Representative query and transaction results |
| Rebuilding procedural logic | PL/oraSQL and Package | Compile, state, and execution outcomes |
| Replacing metadata queries | Oracle-oriented dictionary views | Fields used by administrative workflows |
| Redesigning remote access | DBLINK and foreign-data paths | Read/write, key, and transaction expectations |
| Rebuilding continuity | Replication, RMAN2, and Shield | Recovery, failover, reconnect, and runbook evidence |
What a PoC should resolve
- Can representative applications connect through the intended endpoint?
- Are required types, SQL semantics, objects, and procedural behaviors preserved?
- Are transaction isolation, error behavior, and client tooling acceptable?
- Which compatibility settings are required?
- Which documented boundaries affect the workload?
- Do backup, recovery, replication, and failover meet the selected topology’s objectives?
- Which remaining items are application changes, operational changes, or open decisions?
The useful output is a decision record: retained behavior, required configuration, verified changes, and unresolved risk.