[postmodern-devel] Multiple connections and connection pools

[Slobodan Milnović]

Hi,

I have a bit of a problem understanding how multiple connections and
connection pools work.

What I would like to do is to open an connection to the database, read
several rows from one table with doquery, and for each read row
analyze data, and if conditions are met, write a row to another table.
I'd rather not use memory to store the results from the first query
because I am a bit memory constrained.

I have tried the following (just the simplification of the actual
code), for which I get the message "Database error: This connection is
still processing another query."

(defvar *db-parameters* (list "databasename" "databaseuser"
"databasepassword" "dbhostaddress" :pooled-p t))
(defmacro with-db (&body body)
  `(postmodern:with-connection *db-parameters*
  , at body))

(defun process-some-stuff ()
  (with-db (postmodern:doquery (read some stuff from a table)
    (several variables)
    (analyze row)
    (if some conditions
       (with-db (postmodern:query (insert stuff into another table)))))))

Also, I have tried using two postmodern:connection and then after each
with-db, but the error is the same.

I understand that when I use ":pooled-p t" postmodern will use some
kind of pool, but I have'nt been able to understand how to use it
properly, nor did I manage to find any kind of solution on the
internet. The test.lisp in postmodern source directory did test the
pool, but  each time the connection was imediatelly closed after
openning it, and there were no examples like in my situation.

Perhaps the nesting of the querries is not allowed in postmodern?