Protocol Compatibility Migration Guide

Overview

This guide helps migrate applications from Oracle 23ai or SQL Server 2022 to HeliosDB while maintaining 95%+ compatibility.

Oracle to HeliosDB Migration

Connection String Changes

Before (Oracle)

jdbc:oracle:thin:@hostname:1521:ORCL

After (HeliosDB with Oracle protocol)

jdbc:oracle:thin:@hostname:1521:heliosdb

No application code changes required - HeliosDB speaks Oracle TNS protocol.

Automatic SQL Translation

HeliosDB automatically translates Oracle-specific SQL to standard SQL:

DUAL Table

-- Oracle syntax (automatically handled)
SELECT SYSDATE FROM DUAL;

-- HeliosDB internal translation
SELECT CURRENT_TIMESTAMP;

NVL to COALESCE

-- Oracle syntax (automatically handled)
SELECT NVL(salary, 0) FROM employees;

-- HeliosDB internal translation
SELECT COALESCE(salary, 0) FROM employees;

DECODE to CASE

-- Oracle syntax
SELECT DECODE(status, 'A', 'Active', 'I', 'Inactive', 'Unknown')
FROM employees;

-- Automatically translated to standard CASE

PL/SQL Migration

Cursor Handling

Oracle PL/SQL (fully supported)

DECLARE
  CURSOR emp_cursor IS SELECT * FROM employees WHERE dept_id = 10;
  emp_rec employees%ROWTYPE;
BEGIN
  OPEN emp_cursor;
  LOOP
    FETCH emp_cursor INTO emp_rec;
    EXIT WHEN emp_cursor%NOTFOUND;
    -- Process record
  END LOOP;
  CLOSE emp_cursor;
END;

✓ HeliosDB Support: 96% compatible - All cursor attributes supported (%FOUND, %NOTFOUND, %ROWCOUNT, %ISOPEN) - BULK COLLECT supported - REF CURSOR (weak and strong) supported

Exception Handling

Oracle PL/SQL (fully supported)

BEGIN
  SELECT salary INTO v_salary FROM employees WHERE emp_id = 999;
EXCEPTION
  WHEN NO_DATA_FOUND THEN
    v_salary := 0;
  WHEN TOO_MANY_ROWS THEN
    RAISE_APPLICATION_ERROR(-20001, 'Multiple records found');
  WHEN OTHERS THEN
    DBMS_OUTPUT.PUT_LINE('Error: ' || SQLERRM);
END;

✓ HeliosDB Support: 95% compatible - All standard exceptions supported - Custom exception support - Exception propagation across blocks

Hierarchical Queries

Oracle CONNECT BY (fully supported)

SELECT employee_id, manager_id, LEVEL, SYS_CONNECT_BY_PATH(name, '/') AS path
FROM employees
START WITH manager_id IS NULL
CONNECT BY NOCYCLE PRIOR employee_id = manager_id
ORDER SIBLINGS BY name;

✓ HeliosDB Support: 93% compatible - CONNECT BY PRIOR fully supported - START WITH clause supported - NOCYCLE keyword for cycle detection - LEVEL pseudo-column - SYS_CONNECT_BY_PATH function - CONNECT_BY_ROOT operator - CONNECT_BY_ISLEAF pseudo-column - ORDER SIBLINGS BY clause

Advanced Functions

String Functions

-- All fully supported
SELECT
  INSTR('hello world', 'world'),           -- Position 7
  SUBSTR('hello', -3, 3),                  -- 'llo' (negative position)
  LPAD('Page 1', 10, '*.'),               -- '*.*.*Page 1'
  TRANSLATE('2KRW229', '0123456789', '----'), -- Result
FROM DUAL;

Analytic Functions

-- Fully supported
SELECT
  employee_id,
  salary,
  RANK() OVER (ORDER BY salary DESC) AS rank,
  DENSE_RANK() OVER (ORDER BY salary DESC) AS dense_rank,
  LAG(salary, 1, 0) OVER (ORDER BY hire_date) AS prev_salary,
  LEAD(salary, 1, 0) OVER (ORDER BY hire_date) AS next_salary
FROM employees;

XMLType and JSON

XMLType

-- Create XML
DECLARE
  xml_doc XMLType;
BEGIN
  xml_doc := XMLType('<employees><employee id="1">John</employee></employees>');

  -- Extract value
  SELECT xml_doc.extract('/employees/employee/text()') FROM DUAL;

  -- Check existence
  IF xml_doc.existsNode('/employees/employee[@id="1"]') = 1 THEN
    -- Node exists
  END IF;
END;

✓ HeliosDB Support: 90% compatible - XMLType creation and storage - extract() with XPath - existsNode() for validation - Basic XSLT transformation

JSON Functions (Oracle 21c+)

-- JSON_VALUE
SELECT JSON_VALUE('{"name":"John","age":30}', '$.name') AS name;

-- JSON_QUERY
SELECT JSON_QUERY('{"items":[1,2,3]}', '$.items') AS items;

-- JSON_TABLE
SELECT jt.*
FROM JSON_TABLE(
  '[{"id":1,"name":"John"},{"id":2,"name":"Jane"}]',
  '$[*]'
  COLUMNS(
    id NUMBER PATH '$.id',
    name VARCHAR2(50) PATH '$.name'
  )
) jt;

✓ HeliosDB Support: 94% compatible

Migration Checklist

• [ ] Test connection string changes
• [ ] Identify PL/SQL packages usage (check compatibility)
• [ ] Review hierarchical queries with cycles
• [ ] Test exception handling edge cases
• [ ] Validate XMLType usage
• [ ] Check JSON path expressions
• [ ] Test cursor-intensive code
• [ ] Verify ROWNUM behavior in complex queries

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SQL Server to HeliosDB Migration

Connection String Changes

Before (SQL Server)

Server=hostname;Database=mydb;User Id=sa;Password=***;

After (HeliosDB with TDS protocol)

Server=hostname;Database=mydb;User Id=user;Password=***;

No application code changes required - HeliosDB speaks TDS protocol.

Automatic T-SQL Translation

TOP to LIMIT

-- SQL Server syntax (automatically handled)
SELECT TOP 10 * FROM employees ORDER BY salary DESC;

-- HeliosDB internal translation
SELECT * FROM employees ORDER BY salary DESC LIMIT 10;

Identity Functions

-- All fully supported
INSERT INTO orders (customer) VALUES ('John');

SELECT @@IDENTITY;        -- Last identity inserted (any table, includes triggers)
SELECT SCOPE_IDENTITY();  -- Last identity in current scope (excludes triggers)
SELECT IDENT_CURRENT('orders'); -- Last identity for specific table

SELECT @@ROWCOUNT;        -- Rows affected by last statement

✓ HeliosDB Support: 97% compatible - Correct scope handling for identity functions - Transaction awareness - Trigger distinction

T-SQL Features

TRY...CATCH

SQL Server T-SQL (fully supported)

BEGIN TRY
  -- Risky operation
  INSERT INTO orders (customer) VALUES ('John');
  UPDATE inventory SET qty = qty - 1 WHERE product_id = 123;
END TRY
BEGIN CATCH
  -- Error handling
  SELECT
    ERROR_NUMBER() AS ErrorNumber,
    ERROR_MESSAGE() AS ErrorMessage,
    ERROR_SEVERITY() AS ErrorSeverity,
    ERROR_STATE() AS ErrorState,
    ERROR_PROCEDURE() AS ErrorProcedure,
    ERROR_LINE() AS ErrorLine;

  ROLLBACK TRANSACTION;
END CATCH;

✓ HeliosDB Support: 95% compatible - Full ERROR_* function support - Nested TRY...CATCH blocks - Severity level handling (errors >= 20 terminate connection) - THROW for re-raising exceptions

Temp Tables and Table Variables

-- Local temp table
CREATE TABLE #temp_orders (
  order_id INT,
  customer VARCHAR(100)
);

-- Global temp table
CREATE TABLE ##global_temp (
  id INT
);

-- Table variable
DECLARE @results TABLE (
  id INT,
  name VARCHAR(100)
);

INSERT INTO @results VALUES (1, 'John');
SELECT * FROM @results;

✓ HeliosDB Support: 94% compatible - Local temp tables (#temp) - session scope - Global temp tables (##temp) - cross-session scope - Table variables (@table) - batch scope - Proper scope enforcement

OUTPUT Clause

-- INSERT with OUTPUT
INSERT INTO products (name, price)
OUTPUT INSERTED.product_id, INSERTED.name
VALUES ('Widget', 9.99);

-- UPDATE with OUTPUT
UPDATE inventory
SET qty = qty - 1
OUTPUT DELETED.qty AS old_qty, INSERTED.qty AS new_qty
WHERE product_id = 123;

-- DELETE with OUTPUT INTO
DECLARE @deleted TABLE (product_id INT, name VARCHAR(100));

DELETE FROM products
OUTPUT DELETED.product_id, DELETED.name INTO @deleted
WHERE discontinued = 1;

✓ HeliosDB Support: 93% compatible - INSERTED and DELETED pseudo-tables - OUTPUT INTO table/variable - Works with triggers (proper isolation)

MERGE Statement

MERGE target t
USING source s
ON t.id = s.id
WHEN MATCHED THEN
  UPDATE SET t.value = s.value
WHEN NOT MATCHED BY TARGET THEN
  INSERT (id, value) VALUES (s.id, s.value)
WHEN NOT MATCHED BY SOURCE THEN
  DELETE
OUTPUT $action, INSERTED.*, DELETED.*;

✓ HeliosDB Support: 92% compatible - Multiple WHEN clauses - WHEN NOT MATCHED BY SOURCE - OUTPUT with $action - Proper transaction handling

Common Table Expressions (CTEs)

Non-Recursive CTEs

WITH sales_summary AS (
  SELECT customer_id, SUM(amount) AS total
  FROM orders
  GROUP BY customer_id
)
SELECT c.name, s.total
FROM customers c
JOIN sales_summary s ON c.id = s.customer_id;

✓ HeliosDB Support: 96% compatible

Recursive CTEs

WITH RECURSIVE numbers AS (
  SELECT 1 AS n
  UNION ALL
  SELECT n + 1 FROM numbers WHERE n < 100
)
SELECT * FROM numbers
OPTION (MAXRECURSION 100);

✓ HeliosDB Support: 96% compatible - MAXRECURSION limit (default 100, max 32767) - Infinite recursion detection - Proper validation (anchor vs recursive member)

JSON Support (SQL Server 2016+)

JSON Functions

DECLARE @json NVARCHAR(MAX) = N'{"name":"John","age":30,"active":true}';

-- JSON_VALUE (scalar extraction)
SELECT JSON_VALUE(@json, '$.name') AS name;
SELECT JSON_VALUE(@json, 'lax $.missing') AS missing; -- Returns NULL (lax mode)
SELECT JSON_VALUE(@json, 'strict $.missing') AS error; -- Raises error (strict mode)

-- JSON_QUERY (object/array extraction)
SELECT JSON_QUERY(@json, '$') AS full_object;

-- JSON_MODIFY
SET @json = JSON_MODIFY(@json, '$.age', 31);
SET @json = JSON_MODIFY(@json, 'append $.hobbies', 'reading');

-- ISJSON validation
IF ISJSON(@json) = 1
  PRINT 'Valid JSON';

-- OPENJSON
SELECT *
FROM OPENJSON(@json)
WITH (
  name NVARCHAR(50) '$.name',
  age INT '$.age',
  active BIT '$.active'
);

-- FOR JSON
SELECT customer_id, name, email
FROM customers
FOR JSON PATH, ROOT('customers'), INCLUDE_NULL_VALUES;

✓ HeliosDB Support: 95% compatible - lax and strict path modes - All JSON functions - FOR JSON AUTO and PATH - Complex path expressions

Migration Checklist

• [ ] Test connection string changes
• [ ] Review @@IDENTITY vs SCOPE_IDENTITY usage
• [ ] Check temp table scope requirements
• [ ] Validate TRY...CATCH error handling
• [ ] Test OUTPUT clause behavior
• [ ] Verify MERGE statement logic
• [ ] Check recursive CTE depth limits
• [ ] Test JSON path modes (lax/strict)
• [ ] Review table variable performance
• [ ] Validate transaction handling

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Performance Optimization Tips

Oracle Protocol

1. Minimize ROWNUM usage: Convert to LIMIT when possible
2. Hierarchical queries: Add NOCYCLE to prevent infinite loops
3. REF CURSOR: Use strong-typed when possible for better optimization
4. Bulk operations: Use BULK COLLECT for better performance

SQL Server Protocol

1. Identity functions: Prefer SCOPE_IDENTITY() over @@IDENTITY
2. CTEs: Set appropriate MAXRECURSION to prevent runaway queries
3. Table variables: Use temp tables for large datasets (better statistics)
4. JSON: Use strict mode only when necessary (lax mode is faster)

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Troubleshooting

Common Issues

Oracle

1. Cursor already open: Check for proper OPEN/CLOSE pairing
2. ORA-01436 (CONNECT BY loop): Add NOCYCLE keyword
3. XMLType parsing errors: Validate XML well-formedness
4. PL/SQL package not found: Check DBMS_* package support

SQL Server

1. Severity 20+ errors: These terminate connection, cannot be caught
2. MAXRECURSION exceeded: Increase limit or optimize recursive query
3. Table variable out of scope: Ensure usage within same batch
4. JSON path errors: Check lax vs strict mode settings

Getting Help

• Documentation: /docs/protocol/MULTI_PROTOCOL_COMPATIBILITY_MATRIX.md
• Test examples: /heliosdb-protocols/tests/
• Issue tracker: GitHub Issues

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Version Compatibility

Database	Tested Versions	Compatibility
Oracle	19c, 21c, 23ai	95%+
SQL Server	2016, 2019, 2022	95%+

Last updated: 2025-01-02 (Agent 26 - Phase 5 Hardening)