Cannot execute multi-statement queries

[begelundmuller]

This didn't take long, but I encountered a bug with the refactored bindings. Seems like prepared statements can't be used for multi-statement queries.

Executing a query that contains multiple statements, such as:

_, err = db.Exec("INSTALL 'json'; LOAD 'json';")
if err != nil {
	fmt.Printf("error: %v", err.Error())
}

Outputs the following error:

error: Invalid Error: Cannot prepare multiple statements at once!

I don't know how other DB drivers deal with this, but one idea is to only use prepared statements for queries that have args? (Not sure if that has its own caveats.)

[marcboeker]

Thanks for reporting this. I've tested multiple statements with other DuckDB drivers (Rust, Python).
The Python driver uses a very clever way of splitting a string of multiple statements into single statements and executing them one by one. They make use of the ExtractStatements method in the C++ API.
Maybe we can leverage this?

Until we have a fix, I would suggest to merge your quick fix. Could you please open a PR?

[begelundmuller]

Yeah, I noticed the ExtractStatements method in the Python driver as well, unfortunately I was not able to find it in the C API. If you can't find it, do you think it makes sense to request DuckDB to add it?

I submitted a PR for my fix, but please beware that I put it together very quickly, so please double-check it before merging.

[marcboeker]

Thanks, I've tested and merged the PR.
I think we should request the ExtractStatements method for the C API, as this would be a cleaner solution. I'll ask them tomorrow.

[marcboeker]

I've reopened this and requested an ExtractStatements function for the C API. See duckdb/duckdb#4977

[marcboeker]

I think we can close this.