Data loading is one of the most critical operations in modern databases—especially in analytics, ETL pipelines, and high-volume transactional systems. Oracle has long supported Direct Load operations for faster data insertion, but earlier versions came with strict limitations.
With the evolution into Oracle Database 26ai, direct load operations have become significantly more flexible and developer-friendly.
In this blog, we’ll explore how Unrestricted Direct Loads in Oracle 26ai remove traditional constraints, improve performance, and simplify application workflows.
What Are Direct Loads in Oracle?
Direct loads are a high-performance method of inserting data into Oracle tables.
Unlike conventional inserts:
- Data is written directly into data blocks
- New extents are allocated efficiently
- Logging and overhead are minimized
👉 This makes direct loads ideal for:
- Bulk data loading
- ETL processes
- Data warehouse operations
Challenges Before Oracle 23c (Now Improved in 26ai)
Before these improvements, direct load operations had several frustrating limitations.
❌ No Query or DML Before Commit
After performing a direct load:
- You could not query the table
- You could not perform additional DML
Until:
👉 A commit was issued
❌ ORA-12838 Error
A common issue developers faced:
ORA-12838: cannot read/modify an object after modifying it in parallel
This error occurred when:
- Trying to access a table after a direct load
- Within the same transaction
❌ Lock Contention Across Sessions
During direct loads:
- The table was locked
- Other sessions had to wait
👉 This caused:
- Delays
- Performance bottlenecks
- Reduced concurrency
❌ Mandatory Commit Requirement
To continue working:
- Applications had to commit immediately after each load
This resulted in:
- Increased overhead
- Less flexible transaction handling
What’s New in Oracle 26ai?
Oracle 26ai introduces Unrestricted Direct Loads, removing many of these limitations.
Key Enhancements
1. Query Without Commit
You can now:
- Query the table immediately after a direct load
- Without issuing a commit
👉 This is a major improvement for real-time data workflows
2. Perform Additional DML in Same Session
Within the same session, you can:
- Run
UPDATE,DELETE, orMERGE - After a direct load
👉 No need to break transactions
3. Multiple Direct Loads Without Commit
You can:
- Perform multiple direct loads
- In a single transaction
👉 This simplifies bulk data operations significantly
4. Cross-Session Improvements
Other sessions can now:
- Query the same table
- Perform conventional DML
👉 Improved concurrency and collaboration
5. Rollback Support
You can:
- Roll back to a savepoint
- Within the same transaction
👉 Adds flexibility and control
How It Works Behind the Scenes
Previously:
- Direct loads delayed moving the high water mark (HWM)
- Until commit
This caused:
- Restricted access
- Locking issues
Now:
- Oracle manages access more intelligently
- Reduces blocking and contention
👉 Result: More parallelism, less waiting
Remaining Restrictions
While many limitations are removed, some still apply.
❌ Supported Table Types
Only supported:
- Heap tables
Not supported:
- Index Organized Tables (IOT)
- Clustered tables
❌ Tablespace Requirements
Must use:
- Automatic Segment Space Management (ASSM)
Not supported:
- Uniform extent tablespaces
- Temporary tablespaces
👉 These conditions are important for enabling the feature
New Hints for Direct Loads
Oracle introduces improved hint control:
✅ Enable Multi-Append:
INSERT /*+ APPEND MULTI_APPEND */ INTO sales ...❌ Disable Multi-Append:
INSERT /*+ NO_MULTI_APPEND */ INTO sales ...
👉 These hints allow fine control over direct load behavior
Benefits of Unrestricted Direct Loads
1. Improved Performance
- Faster data loading
- Reduced commit overhead
- Better concurrency
2. Flexible Transactions
- No forced commits
- Continuous workflow execution
3. Developer-Friendly
- Simpler application logic
- Fewer errors (like ORA-12838)
4. Better Data Processing
- Real-time analytics
- Continuous ETL pipelines
- Faster reporting
5. No Extra Storage Overhead
- No additional space usage
- No fragmentation issues
👉 Efficient and scalable
Real-World Use Cases
🔹 ETL Pipelines
- Load → transform → query
- All in one transaction
🔹 Data Warehousing
- Continuous data ingestion
- Faster updates to fact tables
🔹 Reporting Systems
- Immediate data availability
- No waiting for commits
🔹 Batch Processing
- Execute multiple loads and updates
- Without interruption
Best Practices
To get the most out of this feature:
✔️ Use Heap Tables
Ensure your tables support direct load improvements
✔️ Enable ASSM Tablespaces
Required for unrestricted behavior
✔️ Use Multi-Append Wisely
Optimize bulk loads with proper hints
✔️ Monitor Concurrency
Take advantage of improved multi-session access
Common Mistakes to Avoid
- ❌ Using unsupported table types
- ❌ Ignoring tablespace configuration
- ❌ Overusing direct loads unnecessarily
- ❌ Not testing transaction behavior
Final Thoughts
Oracle 26ai’s Unrestricted Direct Loads is a major step forward in database performance and usability.
✔️ Key Takeaways:
- Removes commit-based restrictions
- Allows query and DML after direct load
- Improves concurrency across sessions
- Simplifies application workflows
👉 With these improvements, Oracle makes it easier to build high-performance, real-time data pipelines without unnecessary complexity.
