Thread: Problem with SQLColAttributes(SQL_COLUMN_DISPLAY_SIZE)

Hi all,


After I have had recently updated a number of components on my system
(W2K, Cygwin), I have today started to pick up a PostgreSQL project
that I had lying around.  First I also got a recent ODBC driver.
After that one of the first things I noticed was a new bug, that I
promptly investigated.

The symptom is that the expression "SELECT COUNT(*) FROM anytable"
returns an empty string.  Actually the same happens with any aggregate
function that I have tried.

Delving into the C source of the ODBC wrapper I am using, I find that
this function call

  rc = SQLColAttributes(stmt, col, SQL_COLUMN_DISPLAY_SIZE,
      NULL, 0, NULL, &cbValueMax);

puts 0 into "cbValueMax".

The implementation of SQLColAttributes() in psqlodbc/results.c has
this handler (code re-wrapped to 80-character lines)

  case SQL_COLUMN_DISPLAY_SIZE: /* == SQL_DESC_DISPLAY_SIZE */
      value = fi ? fi->display_size : pgtype_display_size(stmt,
                                         field_type, col_idx, unknown_sizes);

      mylog("PGAPI_ColAttributes: col %d, display_size= %d\n", col_idx, value);

      break;

And indeed I find that log entry in my log files:

  [2124]PGAPI_ColAttributes: col 0, display_size= 0

The variable "fi" is only set, when "ci->drivers.parse" is true, so I
deactivate the checkbox "Parse Statements" on the data source and my
aggregates begin to work again.  So I have a workaround.


Questions:

- Why is "fi->display_size" not set for aggregate function results?

- If that is intentional or unavoidable, shouldn't the code in
  psqlodbc/results.c read

      value = fi && 0 != fi->display_size
          ? fi->display_size
          : pgtype_display_size(...

  or something similar?


benny

Hi all,


Is nobody interested in this bug?  Or maybe it isn't a bug and I am
just misunderstanding something?  "Is there anybody out there?" ;-)


Benjamin Riefenstahl <Benjamin.Riefenstahl@epost.de> writes:
> The symptom is that the expression "SELECT COUNT(*) FROM anytable"
> returns an empty string.  Actually the same happens with any
> aggregate function that I have tried.
>
> Delving into the C source of the ODBC wrapper I am using, I find
> that this function call
>
>   rc = SQLColAttributes(stmt, col, SQL_COLUMN_DISPLAY_SIZE,
>       NULL, 0, NULL, &cbValueMax);
>
> puts 0 into "cbValueMax".


benny