How to Resolve the "LOB Segment Cannot Be Extended" Error

Introduction

In the world of databases, encountering error messages that seem confusing at first glance is not uncommon. A frequent error message in Oracle databases is: "LOB segment cannot be extended". In this post, you will learn what this error message means, why it occurs, and how you can resolve it.

What Does the Error Message Mean?

The error message "LOB segment cannot be extended" indicates that a Large Object (LOB) in the database no longer has enough space to grow. This happens when the allocated space (tablespace) for the LOB is full.

Why Does This Error Occur?

This error can occur for several reasons:

• Insufficient Space: The tablespace where the LOB is stored does not have enough free space.
• Lack of Auto-Extension: The database file is not configured to automatically extend.
• Limited Maximum Size: There is a set maximum size for the tablespace that has been reached.

How to Resolve This Error

To resolve this error, you can take the following steps:

• Check Available Space: Run an SQL script to check the current space and free space in the tablespaces.

 

SQL

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10

 

1

SELECT 

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    dt.tablespace_name,

3

    SUM(df.bytes) / 1024 / 1024 AS Total_MB,

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    SUM(fs.bytes) / 1024 / 1024 AS Free_MB

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FROM 

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    dba_tablespaces dt

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    JOIN dba_data_files df ON dt.tablespace_name = df.tablespace_name

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    LEFT JOIN dba_free_space fs ON dt.tablespace_name = fs.tablespace_name

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GROUP BY 

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    dt.tablespace_name;

• Find the Database File: Determine the exact file representing the tablespace to check its properties.

 

SQL

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1

SELECT 

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    file_name,

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    bytes / 1024 / 1024 AS Size_MB,

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    autoextensible,

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    maxbytes / 1024 / 1024 AS Max_Size_MB

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FROM 

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    dba_data_files

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WHERE 

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    tablespace_name = 'APEX_2200';

• Extend the Tablespace: Log in as a DBA and configure the database file to auto-extend.

 

SQL

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ALTER DATABASE DATAFILE '/opt/oracle/oradata/ORCL/ORCLPDB/APEX_2200.dbf' 

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AUTOEXTEND ON NEXT 100M MAXSIZE UNLIMITED;

• Test the Changes: Verify that the changes were successful and that the file is now auto-extensible.

 

SQL

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11

 

1

SELECT 

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    file_name,

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    autoextensible,

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    increment_by * block_size / 1024 / 1024 AS increment_size_MB,

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    maxbytes / 1024 / 1024 AS max_size_MB

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FROM 

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    dba_data_files

8

JOIN 

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    dba_tablespaces ON dba_data_files.tablespace_name = dba_tablespaces.tablespace_name

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WHERE 

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    file_name = '/opt/oracle/oradata/ORCL/ORCLPDB/APEX_2200.dbf';

Conclusion

Resolving the "LOB segment cannot be extended" error is crucial to ensure the performance and reliability of your Oracle database. By understanding the causes and applying the right solutions, you can ensure that your database operates smoothly.

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