Andrew Dunstan írta:
Mark Woodward wrote:
"Jim C. Nasby" <[EMAIL PROTECTED]> writes:
On Mon, Jun 05, 2006 at 11:27:30AM -0400, Tom Lane wrote:
I'm reading this as just another uninformed complaint about libpq's
habit of buffering the whole query result. It's possible that
there's
a memory leak in the -A path specifically, but nothing said so far
provided any evidence for that.
Certainly seems like it. It seems like it would be good to allow for
libpq not to buffer, since there's cases where it's not needed...
See past discussions. The problem is that libpq's API says that
when it
hands you back the completed query result, the command is complete and
guaranteed not to fail later. A streaming interface could not make
that
guarantee, so it's not a transparent substitution.
I wouldn't have any strong objection to providing a separate API that
operates in a streaming fashion, but defining it is something no one's
bothered to do yet. In practice, if you have to code to a variant API,
it's not that much more trouble to use a cursor...
Wouldn't the "COPY (select ...) TO STDOUT" format being discussed solve
this for free?
Yes, it would for me.
It won't solve it in the general case for clients that expect a result
set. ISTM that "use a cursor" is a perfectly reasonable answer, though.
The general case cannot be applied for all particular cases.
E.g. you cannot use cursors from shell scripts and just for
producing an "export file" it's not too reasonable either.
Redirecting psql's output or COPY is enough.
Best regards,
Zoltán Böszörényi
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