Re: exceeded MAX_ALLOCATED_DESCS while trying to open file

The csv has 34 columns and I need to create a crosstab (using 8 columns so
I can't use built in crosstab functions). That is why I need to make
several sql select.

I'm using foreign table so my client can update is csv file without having
to run the ETL to update a table in postgres.
Using temporary table means I got to know when the csv is updated...unless
there is something I misunderstood.

Perhaps the solution is to automate the process to copy the csv in a
table.....

"ktm(at)rice(dot)edu" <ktm
2013-05-28 11:48

A
Steve(dot)Toutant(at)inspq(dot)qc(dot)ca
cc
pgsql-admin(at)postgresql(dot)org
Objet
Re: [ADMIN] exceeded MAX_ALLOCATED_DESCS while trying to open file

On Tue, May 28, 2013 at 11:28:02AM -0400, Steve(dot)Toutant(at)inspq(dot)qc(dot)ca wrote:
> Hi,
> Using postgres 9.2, I created a FOREIGN TABLE on a csv file. It works.
> But I need to change the structure of the data and I created several sql

> select using union, like
> select .... from .foreign table... where...
> union
> select .... from .foreign table... where...
> union
> ...
> It works for the first 10 select but then I get
> ERROR: exceeded MAX_ALLOCATED_DESCS while trying to open file
> "/srv/www/data/antidote/registre.csv"
>
> What is it MAX_ALLOCATED_DESCS? and how can I modify it without changing

> the code and re-compile? I tried using postgref.conf but this parameters

> is not recognize.
> thanks
> steve

Hi Steve,

Each SELECT opens your FOREIGN TABLE so you are opening it 10 times. This
is
hardcoded by a #define in ./src/backend/storage/file/fd.c during the build
so
you would need to recompile the software yourself to change it. Can you
re-
write your query using a single SELECT or possibly read the data into a
temporary table for processing?

Regards,
Ken