I'm writing a server that uses a postgresql database, it uses r2d2_postgres for connection pooling. I have a few queries that I'd like to prepare, and there's a prepare() method that returns a Statement. I figured I'd use the connection pool's CustomizeConnection::on_acquire() to prepare the statement. However, I discovered that there's no good place to actually store the Statement (so that is associated with the connection Client).

I figured I'd fall back to using SQL PREPARE and EXECUTE instead.

I prepare a plan using:

  dbclnt.simple_query(
    "PREPARE authplan (TEXT, TEXT) AS
SELECT * FROM users WHERE name=$1 AND passhash = crypt($2, salt);"
  )?;

..and later I attempt to execute it using:

  let row = dbclnt.query_opt("EXECUTE authplan($1, $2);", &[&name, &pass])?;

.. but I get an expected 0 parameters but got 2 error when I do so.

I found some older post about using r2d2 with postgres and prepared statements, which indicates that it used to have a prepare_cached, which does not appear to still be available.

Anyone know why the SQL version doesn't work? Why is it telling me it expected 0 parameters? Or does anyone know how to store/retrieve a Statement when using the r2d2 connection pool?

(One can always create a server-side PL/pgSQL function, but that feels kind of derpy for really small things).

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