[Dev-C++] RE: ODBC for free tables (Was: SQL "SELECT COUNT(*)" loads whole table into memory)

[Ed C. <em...@ed...>]

Hi all,

I'm going to try rephrasing my question. If I'm using an ODBC driver to
connect to a Visual FoxPro (.dbf) data file, can I run queries without
loading the whole file into memory? For example, if I just want to count
records in a table, I would run the query "SELECT COUNT(*) FROM
[c:\somefile.dbf]", but the ODBC driver loads the whole table into RAM =
to
figure this out. How can I do this better?=20

Thanks for any help.

-Ed



-----Original Message-----
Sent: Friday, January 02, 2004 2:00 AM
To: dev...@li...
Subject: [Dev-C++] SQL "SELECT COUNT(*)" loads whole table into memory


Hi all,

Not technically a Dev-Cpp question, but I'm hoping somebody can help,
anyway. I'm working with an ODBC driver for Visual FoxPro 6 (as well as =
ODBC
drivers for several other RDBMSs). My application is supposed to loop
through a list of tables, run the single SQL statement "SELECT COUNT(*) =
FROM
tblname", get the result, then move on. At the end, I go back and tally =
all
the row counts.

In the process, I am simply reusing all my handles (environment,
connections, and recordsets), calling SQLGetData and SQLCloseCursor =
after
each query.

Now, here's the problem: even though I'm just doing SELECT COUNT(*), the
entire table is getting loaded into memory. My application's memory =
usage
goes from 6 MB to 100 +, though if I comment out just the FoxPro =
database
interaction, it stays around 8 MB, where I would expect it to be. The =
logic
and coding I'm doing for the FoxPro queries is absolutely identical to =
the
logic I'm using on the other databases, except, of course, for the
connection string, and I'm not having this problem with the other =
systems. I
should also point out that removing some of the larger tables from the =
list
of tables to check results in an almost perfectly corresponding drop in =
RAM
usage.

For what it's worth, doing the same query directly from Visual FoxPro 6
results in a RAM spike under 1 KB.

Anybody know what's wrong? Is there a driver setting I need to use or
something?

Thanks!

-Ed