ORA-01652: Unable to Extend Temp Segment – Complete Fix Guide

The ORA-01652: unable to extend temp segment error occurs when Oracle Database cannot allocate additional space in the temporary tablespace (TEMP) during query execution.

This issue is very common in systems running large queries, sorting operations, or batch jobs and if not handled properly, it can impact performance and even stop critical processes.

In this guide, you’ll learn how to quickly fix ORA-01652 and prevent it permanently using real-world DBA solutions.

What is ORA-01652 Error?

Oracle uses temporary tablespace for operations like:

• Sorting (ORDER BY)
• Joins and aggregations
• Index creation
• Temporary data processing

When TEMP runs out of space, Oracle throws:

ORA-01652: unable to extend temp segment by <n> in tablespace TEMP

Quick Fix (Immediate Solution)

If you're in a hurry, run this:

 ALTER TABLESPACE temp ADD TEMPFILE 'temp02.dbf' SIZE 1G; 

Or resize existing tempfile:

 ALTER DATABASE TEMPFILE 'temp01.dbf' RESIZE 2G; 

Common Causes of ORA-01652

• TEMP Tablespace Full
• Large Queries or Joins
• Missing Indexes
• Parallel Execution
• Unoptimized SQL
• Multiple Users Consuming TEMP

Step-by-Step Troubleshooting

1. Check TEMP Tablespace Usage

 SELECT tablespace_name, SUM(bytes)/1024/1024 AS MB FROM dba_temp_files 
 GROUP BY tablespace_name; 

2. Identify Sessions Using TEMP

 SELECT s.sid, s.serial#, s.username, t.blocks*8/1024 AS MB_USED 
 FROM v$sort_usage t, v$session s WHERE t.session_addr = s.saddr; 

This helps you find which session is consuming TEMP space.

3. Check Free Space

 SELECT tablespace_name, SUM(bytes_free)/1024/1024 AS FREE_MB FROM v$temp_space_header 
 GROUP BY tablespace_name; 

4. Kill Problematic Sessions (if required)

 ALTER SYSTEM KILL SESSION 'SID,SERIAL#' IMMEDIATE; 

Use with caution in production environments.

5. Add or Resize TEMPFILE

 ALTER TABLESPACE temp ADD TEMPFILE 'temp02.dbf' SIZE 1G AUTOEXTEND ON; 

Special Case: ORA-01652 During Large Queries

Heavy queries like this can cause the issue:

 SELECT * FROM large_table1 t1 JOIN large_table2 t2 ON t1.id = t2.id 
 ORDER BY t1.created_date; 

Fix:

• Add indexes
• Remove unnecessary ORDER BY
• Use WHERE filters

Real-World Scenario

A batch job failed nightly with ORA-01652 during data processing.

Root Cause: Large join without index + small TEMP tablespace

Solution:

• Added index on join columns
• Increased TEMP size
• Enabled AUTOEXTEND

Result: Job executed successfully without errors.

Best Practices to Prevent ORA-01652

• Enable AUTOEXTEND on tempfiles
• Monitor TEMP usage regularly
• Optimize SQL queries
• Avoid unnecessary sorting
• Use proper indexing
• Limit parallel execution where needed

Frequently Asked Questions (FAQ)

Can I delete TEMP files?

No, but you can resize or recreate them safely.

Is ORA-01652 a serious error?

Yes, it can stop queries and batch jobs.

How much TEMP space is enough?

Depends on workload monitor and adjust dynamically.

Related Posts

• ORA-00942: Table Not Found
• ORA-00001: Unique Constraint
• ORA-12154: TNS Error

Final Thoughts

The ORA-01652 error is mainly a resource limitation issue. While increasing TEMP space provides a quick fix, the real solution lies in query optimization and proper monitoring.

By applying the strategies in this guide, you can eliminate this error and significantly improve database performance.