Ora 01652-unable-to-extend-temp-segment-by-128-in-tablespace-temp

8 min read Oct 11, 2024

The error message "ORA-01652: unable to extend temp segment by 128 in tablespace TEMP" is a common issue encountered in Oracle databases. This error indicates that the temporary tablespace, designated as "TEMP," is unable to allocate sufficient space to accommodate a temporary segment. This segment is required by the database for various operations, such as sorting, joining, and subquery processing.

Let's delve into the reasons behind this error and explore potential solutions to address it.

Understanding the Error

This error message is triggered when the Oracle database needs to expand the temporary segment in the TEMP tablespace, but it lacks the necessary space to do so. The error message includes "128," which represents the number of blocks requested for the extension. This signifies that the database attempted to enlarge the temporary segment by 128 blocks, but the available space in the TEMP tablespace was insufficient.

Potential Causes

Several factors can contribute to the "ORA-01652" error. Let's examine some common culprits:

Insufficient TEMP Tablespace Size: The most straightforward reason is that the TEMP tablespace is simply too small to handle the temporary segment expansion request.
High Usage of TEMP Tablespace: If numerous users or applications are concurrently accessing and using the TEMP tablespace, it can easily become saturated, leading to the inability to extend temporary segments.
Defragmentation Issues: Fragmentation within the TEMP tablespace can hinder the database's ability to allocate contiguous space for segment expansion.
Temporary Segment Size: If the default temporary segment size (typically 64 blocks) is insufficient for a particular operation, it can trigger the error.
SQL Query Complexity: Complex SQL queries, especially those involving large data volumes, may require extensive temporary space, increasing the likelihood of the error.

Troubleshooting Steps

Check TEMP Tablespace Size: Begin by verifying the size of your TEMP tablespace. Use the following SQL statement:
```
SELECT tablespace_name, SUM(bytes) / 1024 / 1024 AS total_mb
FROM dba_data_files
WHERE tablespace_name = 'TEMP';
```
If the size appears inadequate, consider increasing it.

Monitor TEMP Tablespace Usage: Monitor the utilization of the TEMP tablespace to identify potential spikes in usage. You can use the following SQL statement:

SELECT s.tablespace_name, 
       s.seg_type,
       SUM(s.bytes) / 1024 / 1024 AS total_mb,
       s.seg_used / 1024 / 1024 AS used_mb,
       ((s.seg_used / s.bytes) * 100) AS percentage_used
FROM dba_segments s
WHERE s.tablespace_name = 'TEMP'
GROUP BY s.tablespace_name, s.seg_type, s.seg_used, s.bytes
ORDER BY s.tablespace_name, s.seg_type;

If the TEMP tablespace usage consistently approaches its capacity, you might need to expand its size or optimize the queries that heavily utilize it.

Defragmentation: Consider defragmenting the TEMP tablespace to enhance its space allocation efficiency. You can use the DBMS_SPACE_ADMIN package for this purpose.
Increase Temporary Segment Size: For complex queries or operations that demand larger temporary segments, you can increase the default size. This can be accomplished using the following SQL statement:
```
ALTER SESSION SET TEMPORARY_SEGMENT_SIZE = 128;
```
Replace "128" with the desired segment size in blocks.
Optimize SQL Queries: Identify queries that are particularly intensive in their usage of the TEMP tablespace and optimize them to reduce their temporary storage requirements.
Review User Sessions: Analyze user sessions to identify any queries or activities that might be consuming a disproportionate amount of temporary space.
Increase Physical RAM: While not directly related to the TEMP tablespace, increasing your physical RAM can reduce the pressure on the temporary storage by allowing the database to cache more data in memory.

Resolution Examples

Expanding TEMP Tablespace: To expand the TEMP tablespace, you can add a new data file to it. For instance, to add a 10 GB data file:
```
ALTER TABLESPACE TEMP ADD DATAFILE '/path/to/new/temp/datafile.dbf' SIZE 10G;
```
Optimizing a Query: Consider a query that performs an expensive sort operation on a large table:
```
SELECT *
FROM large_table
ORDER BY column1, column2;
```
To reduce the temporary space required, you can add a suitable index on the columns used in the ORDER BY clause.
Defragmentation: Using DBMS_SPACE_ADMIN, you can defragment the TEMP tablespace as follows:
```
BEGIN
  DBMS_SPACE_ADMIN.FRAGMENT_TABLESPACE('TEMP');
END;
/
```

Conclusion

The "ORA-01652" error signifies that the temporary tablespace is insufficient to support the requested segment extension. By analyzing the underlying cause, whether it's inadequate space, excessive usage, or other factors, you can adopt appropriate solutions such as increasing the TEMP tablespace size, optimizing queries, or defragmenting the tablespace. Addressing this error is crucial to ensuring optimal performance and preventing further database operations from being interrupted. Remember to back up your database before making any significant changes to your tablespaces.