topic Re: Problem with calculate size/length on column. in Qlik Replicate

Problem with calculate size/length on column.

data_engineer_whop — Fri, 23 Jan 2026 08:32:07 GMT

Hi ,

I have question to calculate length or size with type of column NCLOB /CLOB. This column is document pulled from MOngo db and typical length function returns 0 or null. We tried to do it via global rule and direct operation on column in specific table.

Thanks for any tips and support.

Regards

Re: Problem with calculate size/length on column.

SachinB — Fri, 23 Jan 2026 10:14:12 GMT

Hello @data_engineer_whop ,

LENGTH() is designed for VARCHAR2 / CHAR, not for LOBs.

SELECT LENGTH(your_clob_column) FROM your_table; is always returns zero or null

It appears that is not supported when LOB/CLOB/NLOB data types return zero or null.

Regards,
Sachin B

Re: Problem with calculate size/length on column.

data_engineer_whop — Mon, 26 Jan 2026 14:02:12 GMT

Yes but when we try to do length(X) it doesn t give us number of bytes ..there is still null. Here is a problem . Number of bytes would be still nice for us.

Any ideas ?

Re: Problem with calculate size/length on column.

Dana_Baldwin — Mon, 26 Jan 2026 17:44:55 GMT

Hi @data_engineer_whop

Just to confirm, the LOB column for the row you are working with is not NULL, is that correct? If it is NULL, a check of it's length will always be NULL as it is undefined and mathematical checks of it cannot be determined. Could you use an IFNULL then 0 in your transformation?

Thanks,

Dana

Re: Problem with calculate size/length on column.

DesmondWOO — Tue, 27 Jan 2026 11:37:14 GMT

Hi @data_engineer_whop ,

It appears that we cannot apply any functions to the column '_doc'. I recommend using a function on the target table to get the length. For example, in SQL Server, I can use LEN() to determine the length of the JSON data.

Regards,
Desmond

Re: Problem with calculate size/length on column.

data_engineer_whop — Tue, 27 Jan 2026 16:03:48 GMT

@Dana_Baldwin & @DesmondWOO thanks for your answers :). We don't care honestly if we have 0 or null as far as it is not result of length in bytes or in number characters. So the information below that telling us to use on blob length function to get number of bytes is wrong 😞

Re: Problem with calculate size/length on column.

Dana_Baldwin — Tue, 27 Jan 2026 21:46:19 GMT

Hi @data_engineer_whop

I think the hint in the software is correct for endpoints that support data enrichment, but unfortunately MongoDB is not an endpoint that supports data enrichment. I apologize for not checking that before, it is documented here:

Functions | Qlik Replicate Help

It appears that MongoDB supports this via:

$strLenCP → Counts the number of UTF-8 code points (characters).
$strLenBytes → Counts the number of bytes in the UTF-8 encoding.

Based on this I am not sure why there is a limitation within Qlik Replicate. If this is a feature you would like to see in the product, I encourage you to please submit a feature request here which goes directly to our Product Management team. Other users will have the opportunity to vote on it to increase the chances at adoption (if there is no technical obstacle) and to set the priority: https://community.qlik.com/t5/Ideas/idb-p/qlik-ideas

Thanks,

Dana