PostgreSQL 8.3 or later: Query failed: ERROR: operator does not exist

As a way to speed things up, do you know exactly what changes would be necessary in the SQL for PostgreSQL?

Unfortunately, no. I know that casting issues are problematic to tackle in an cross-DBMS way. The best would be revising the design to avoid casts entirely, but I guess that this would be too much work.

The module generates many where clauses using the '%s >= %u' pattern. I know that enclosing the integer between single quotes (that is, '%s >= \'%u\') would work in both MySQL and PostgreSQL. I have tried to make such changes, but I still get query errors (or, maybe, I have generated different errors). I will try to look into the code further (I'd really need the module to work), but I cannot guarantee a patch.

Eventually, it was not too difficult to circumvent implicit casts: I just had to add more checks based on the value of $use_timestamp. Attached you find a patch, which I have tested with PostgreSQL 8.4 and it works for me. I have not tested it with MySQL, but I see no reason why it shouldn't work there as well.

In a couple of places, I have also changed dates of the form YYYY-MM-00 to YYYY-MM-01, because the former is not a valid date value in PostgreSQL. I have no idea whether this change would cause wrong ranges to be generated.

No, I did not get errors: that was precautionary :)

I do not understand the logic of get_last_day_of_* functions, actually. Say, get_last_day_of_month_from_reference contains the following conditional:

if ($use_timestamp) {
      $last = ($month == 12) ?
        ($year + 1) . '-01-01' :
        sprintf('%04u-%02u-01', $year, $month + 1);
    }
    else {
      $last = ($month == 12) ?
        $year . '-12-31' :
        sprintf('%04u-%02u-00', $year, $month + 1);
    }
    $last = strtotime($last);
    if (!$use_timestamp) {
      $last = date('Ymd', $last);
    }
    return $last;

As far as I can see, if $use_timestamp is false, that function returns a date in YYYYMMDD format. The latter is obtained by converting the $last timestamp, which, unless the month is December, has been obtained from a string YYYY-MM-00. Wouldn't this result in an invalid date? Or am I missing something?

Ah, ok, date(strtotime('YYYY-MM-00')) yields a correct date. I agree, then, that there is no need to change the day to 01.

Here is the updated patch.