Question

I’m using IBM DB2 9.7.2 on Debian GNU/Linux. I need a conditional DROP INDEX, only if it exists. As it’s not supported I wrote a procedure that accepts IN idx_name VARCHAR(128) as index name. In the procedure I check if index with that name exists in SYSCAT.INDEXES, and if yes I execute

DROP INDEX idx_name;

But apparently DROP INDEX does not accept string.

Alternatively I tried using SYSPROC.SYSTS_DROP() but it gave me an error:

SQL20427N An error occurred during a text search administration procedure or
command. The error message is “CIE00340 Cannot start executable program
“cieadmsv”. “. SQLSTATE=38H14

I probably could modify a procedure to do drop that index and catch an exception so that there is no error if that does not exist but I still don’t know: how can I make DROP INDEX to accept the variable?

Answer 1

DROP INDEX, like most of SQL, doesn’t accept parameters for identifiers (you can’t do this with SELECT statements either). I expect this has to do with the optimizer attempting to validate/prepare the statement – you can only specify them for column contents, after all.

You have two options:

1. Use Dynamic SQL to create the statement, PREPARE and EXECUTE. You should be able to do this from within your stored procedure. However, I’d be careful with this, as it may enable unauthorized people to delete indicies (depending on how the procedure is setup).
2. Ignore the error. Specifically, ignore SQLCODE -204 (well, that’s the iSeries DB2 code). So what if it doesn’t exist? We were trying to remove it anyways… Other errors should still be reported/dealt with.