Skip binding of missing parameter placeholders

[vibridi]

This is more of a question than an actual bug report:

Code Example

func doQuery(...) ([]interface{}, error) {
	args := []interface{}{
		"foo",
		2,
		"bar",
	}
	query := `
SELECT * FROM my_table m WHERE m.count = $2 AND m.title = $3
`
	db.SelectContext(ctx, dest, query, args...)
}

Here I have a query with three arguments but only two parameter placeholders, starting from $2.

Expected
Not sure if it's reasonable to expect this: intuitively, I would like simply $2 to bind to the second param 2, and $3 to bind to the third param bar.

Actual
pq: could not determine data type of parameter $1 (even though there's no $1 param in the source query).

Of course it's reasonable that the lib complains about mismatches between input arguments and placeholders, but I also wonder if it would equally make sense to handle this case more gracefully; i.e. as long as the length of args is >= the highest number among placeholders, it might as well not fail.

Use Case
My use case is a big query with a few UNION'ed blocks that is composed dynamically.
Let's say I have three main sub-queries A,B and C, where:

• A contains a $1 placeholder
• B and C don't
• the composed query Q might be either only A, A U B U C or B U C according to a bunch of if conditions.
  So the params $2, $3, $x are the same in all A,B, C chunks, except that A has also $1.

I would like to hear your opinion on this.

[johto]

Of course it's reasonable that the lib complains about mismatches between input arguments and placeholders, but I also wonder if it would equally make sense to handle this case more gracefully; i.e. as long as the length of args is >= the highest number among placeholders, it might as well not fail.

The server doesn't accept it, so this is a non-starter:

=# prepare qwr as select $2;
ERROR:  could not determine data type of parameter $1