Toad World® Forums

Compare Data on a Table containing CLOB corrupts the DATA in the target



When comparing data between two schemas, if one of the fields is a CLOB and there is a difference in aonther field, the resulting update script includes an update of the CLOB field that results in erroneous data.

The update stataement does not replace the data with the data from the source but it adds part of the data to what already exists.

This behavior is similar to what I complained about here:

Whereas that was anuisance reaulting in the way I used the resulting script, the issue I have here is clearly a BUG.


Shimon J.



Thanks for your input. I have not been able to recreate this with a small-ish CLOB (10,000 bytes).

How long is your CLOB?

What version of Toad are you using?


Hi Jeff,

The content of the CLOB is quite small. The field size is large, but I’ll have to check next week to see the exact size.

I’m using Toad for zOS version 6.3 and the 6.5 BETA. It happens in both versions.

Shimon J.


I’m using Toad 6.5 and the CLOB size is (1048576). This happens consistently, and any upserts ( INSERTS based on compare to an empty REF table, and then update based on compare DATA) that I run corrupt the data.

Even if the difference in DATA is in a different field.