How to Handle Oracle's ORA-01489: 'Result of String Concatenation is Too Long'?

Error Handling in Oracle: ORA-01489: Result of String Concatenation is Too Long

Oracle's ORA-01489 error occurs when the result of a string concatenation exceeds the maximum allowed length. However, this error can sometimes be misleading.

Case 1: Exceeding the SQL Limit

The default SQL limit for string concatenation is 4000 bytes. Concatenating strings beyond this limit triggers the ORA-01489 error. This applies to the LISTAGG function as well.

Workaround:

Use XMLAGG instead of LISTAGG, as it allows for larger concatenated strings.

Case 2: Concatenating Multiple Long Columns

If you are concatenating multiple columns that each exceed 4000 bytes, the result can still trigger the error.

Workaround:

Concatenate the XMLAGG output of each column to avoid the SQL limit. For example:

SELECT rtrim(xmlagg(XMLELEMENT(e,col1,',').EXTRACT('//text()') ).GetClobVal(), ',')
       || 
       rtrim(xmlagg(XMLELEMENT(e,col2,',').EXTRACT('//text()') ).GetClobVal(), ',') 
       AS very_long_text
FROM DATA
GROUP BY ID
ORDER BY ID;

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