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On Wed, Apr 27, 2005 at 02:34:26PM -0400, Mak, Jason wrote:
>
> Yes, my application is a client application that uses libpq api, ie.
> PQexec, etc... I have looked at the "Functions Associated with the COPY
> Command". But I still don't understand. what I really need is an
> example of how those api's(PQputCopyData) are used, other than the
> "simple" example that's provided.
What example are you looking at and what don't you understand about it?
> This "dataload" should be relatively simple. I already have a flat
> file created. I should be able to use some api and say here is the
> pointer to my db connection and here is a pointer to the flat file.
> now do your thing. Perhaps you can explain this to me.
libpq provides the primitives that you could use to implement such
an API: it would be a trivial matter to write a function that opens
the indicated file, reads its contents, and sends them to the
database. As the documentation indicates, you'd use PQexec() or
its ilk to send a COPY FROM STDIN command (see the COPY documentation
for the exact syntax), then PQputCopyData() or PQputline() to send
the data (probably in a loop), then PQputCopyEnd() or PQendcopy()
to indicate that you're finished. Add the necessary file I/O
statements and there's your function.
Do you have a reason for using an intermediate file? Instead of
writing data to the file and then reading it back, you could use
PQputCopyData() or PQputline() to send the data directly to the
database.
Another possibility: if the file resides somewhere the backend can
read, and if you can connect to the database as a superuser, then
you could use COPY tablename FROM 'filename'.
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
