Resolving ORA-10635 and ORA-39171 Errors During BLOB Tablespace Maintenance

Recently, I came across an interesting situation while performing a space management task on one of our databases. The challenge involved a table that contained BLOB data distributed across multiple tablespaces. What seemed like a simple shrink operation ended up turning into a deeper learning experience that I’d like to share.

🧩 Background

In this environment, the main table BINARY_ARCHIVE was stored in the MAIN_DATA tablespace.
Its BLOB segment was placed separately in the ATTACHMENTS_DATA tablespace to improve performance and manage large object storage efficiently.

Additionally, another table called BINARY_OBJECT_LINK maintained a foreign key reference to the BLOB data and resided in the LINK_DATA tablespace.

When I attempted to reclaim space from the BLOB segment using the SHRINK SPACE command, Oracle returned the following error.

⚠️ The Error


ORA-10635: Invalid segment or tablespace type
10635. 00000 - "Invalid segment or tablespace type"
*Cause:    Cannot shrink the segment because it is not in an auto segment space
           managed tablespace, or it is not a data, index, or LOB segment.
*Action:   Check the tablespace and segment type, then reissue the statement.

The error clearly indicated that the tablespace type didn’t support segment shrink. Upon further checking, I confirmed that the tablespace was dictionary-managed — meaning the shrink feature was not applicable in this case.

🧰 The Workaround

Since the direct shrink operation was not feasible, I decided to rebuild the table by exporting and re-importing it. This approach forces Oracle to recreate the table and its associated LOB segments, effectively reclaiming unused space.

Here’s the detailed sequence of steps I followed:

1️⃣ Export Table

I used Oracle Data Pump to export the existing table


expdp system/****** tables=BINARY_ARCHIVE directory=TMP_DUMP2 \
dumpfile=BINARY_ARCHIVE_EXP.dmp logfile=BINARY_ARCHIVE_EXP.log

2️⃣ Rename and Validate the Existing Table

I first renamed the original table and verified its contents:


ALTER TABLE DATA_OWNER.BINARY_ARCHIVE RENAME TO BINARY_ARCHIVE_OLD;

SELECT * FROM DATA_OWNER.BINARY_ARCHIVE_OLD;

3️⃣ Import the Table

I used Oracle Data Pump to re-import it cleanly:

impdp system/****** tables=BINARY_ARCHIVE directory=TMP_DUMP2 \
dumpfile=BINARY_ARCHIVE_EXP.dmp logfile=BINARY_ARCHIVE_IMP.log

This approach successfully rebuilt the table and its LOB segments, reclaiming unused space and refreshing the internal structure.

😣 The Import Issue — ORA-39171

However, during the import process, the job was suspended with the following error message:


ORA-39171: Job is experiencing a resumable wait.
Resumable error: ORA-01654: unable to extend index SYS_IL0018248660C00003$$ by 512 in tablespace ATTACHMENTS_DATA
Resumable stmt: BEGIN SYS.KUPW$WORKER.MAIN('SYS_IMPORT_TABLE_01', 'SYS', 0); END;
Resumable stmt status: SUSPENDED
Resumable stmt start: 11/06/25 04:54:43
stmt suspend: 11/06/25 07:17:23

This indicated that Oracle could not allocate space for the internal LOB index (SYS_IL...) that manages the BLOB segment. The import job entered a resumable wait state, pausing until additional space became available.

✅ Fixing the Space Issue

To resolve the problem, I first checked the datafiles of the ATTACHMENTS_DATA tablespace:


SELECT FILE_NAME,
       ROUND(BYTES / 1024 / 1024 / 1024, 2) AS BYTES_GB,
       ROUND(USER_BYTES / 1024 / 1024 / 1024, 2) AS USER_BYTES_GB,
       ROUND(MAXBYTES / 1024 / 1024 / 1024, 2) AS MAXBYTES_GB,
       AUTOEXTENSIBLE
FROM dba_data_files
WHERE tablespace_name = 'ATTACHMENTS_DATA';

Then, I enabled autoextend and added a new datafile to ensure sufficient space for LOB data growth:


ALTER DATABASE DATAFILE '/data/oradata2/attachments_data_47.dbf' 
AUTOEXTEND ON MAXSIZE UNLIMITED;

COMMIT;

ALTER TABLESPACE ATTACHMENTS_DATA 
ADD DATAFILE '/data/oradata2/attachments_data_50.dbf'
SIZE 1G 
AUTOEXTEND ON NEXT 300M MAXSIZE UNLIMITED;

After adding space, the suspended import job automatically resumed and completed successfully.

🔍 Monitoring Resumable Sessions

I also monitored resumable operations to ensure the job resumed correctly:


SELECT username, status, start_time, suspend_time, resume_time
FROM dba_resumable
ORDER BY start_time DESC;

💡 Key Takeaways

ORA-10635 occurs when attempting to shrink a segment in a dictionary-managed tablespace.
✅ Ensure the tablespace is locally managed with ASSM before using shrink operations.
When shrink isn’t possible, export/import is the safest and cleanest way to reclaim space.
ORA-39171 / ORA-01654 indicates space allocation problems for internal LOB indexes.
✅ Add or resize datafiles to resolve the issue.
Always monitor resumable statements using the DBA_RESUMABLE view to track suspended operations.

📝 Final Thoughts

What started as a simple shrink operation turned into a valuable troubleshooting session. Managing LOB data across multiple tablespaces can sometimes lead to unexpected challenges, especially with space allocation and segment management.

The key lesson here is simple:
Always review tablespace configuration, monitor space usage proactively, and be ready with an export/import plan for complex LOB segments.

This method not only resolved both the ORA-10635 and ORA-39171 errors but also helped optimize overall tablespace utilization effectively.

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