DB2 LOAD修饰符-GeneratedOverride或IdentityOverride

Question

I am performing a DB2 load, and I am struggling to understand the impact of using GeneratedOverride over IdentityOverride. When I run the following command:

db2 load from tab123.ixf of ixf replace into application.table_abc

All rows are rejected, with the following error being the culprit:

SQL3550W The field value in row row-number and column column-number is not NULL, but the target column has been defined as GENERATED ALWAYS.

So to try and step around this, I executed :

db2 load from tab123.ixf of ixf modified by identityoverride replace into application.table_abc

But this immediately returned this error:

SQL3526N The modifier clause "IDENTITY OVERRIDE" is inconsistent with the current load command. Reason code: "3".

From checking the reason code I see that the issue is "Generated or identity related file type modifiers have been specified but the target table contains no such columns." .. but the SQL3550W error seems to infer that the columns are generated always!

The only way I can get these rows to commit to the table is to run..

db2 load from tab123.ixf of ixf modified by generatedoverride replace into application.table_abc

Can anyone enlighten me to why I am recieving the SQL3526N error, or what the implications of running generatedoverride are?

Thanks for sticking with me..

Answer 1

Generated columns are not necessarily identity columns, apparently that's the case in your situation. Check the CREATE TABLE syntax to see what are other ways to generate column values.

By using the GENERATEDOVERRIDE option during the load you are obviously replacing (overriding) the generated values with those from the input file.