Tom Lane wrote:
Andrew Chernow <[EMAIL PROTECTED]> writes:
PGresult *PQresultDup(
PGconn *conn,
PGresult *res,
int ntups,
int numAttributes,
PGresAttDesc *attDescs);
I don't understand why this is a "dup" operation. How can you "dup"
if you are specifying a new tuple descriptor? I'd have expected
something like
PGresult *PQmakeResult(PGconn *conn, int numAttributes, PGresAttDesc *attDescs)
producing a zero-row PGRES_TUPLES_OK result that you can then load with
data via PQresultSetFieldValue calls. (Even the conn argument is a bit
of a wart, but I think we probably need it so we can copy some of its
private fields.)
Copying an existing PGresult might have some use too, but surely that
can't change its tuple descriptor.
regards, tom lane
Yeah, "dup" wasn't the best name.
You need more arguments to makeresult though, since you reomved the
'source' result. You need binary, cmdStatus, noticeHooks and
client_encoding.
PQmakeResult(conn,
PQcmdStatus(res),
PQbinaryTuples(res),
?client_encoding?,
?noticeHooks?,
ntups, /* this interacts with setfieldvalue */
numAttributes,
attDescs);
For client_encoding and noticeHooks, the conn can be NULL. Previously,
we copied this info from the source result when conn was NULL.
> producing a zero-row PGRES_TUPLES_OK result that you can then
>load with data via PQresultSetFieldValue calls.
I like this idea but you removed the 'ntups' argument. There is no way
to adjust ntups after the makeresult call, its a private member and
setfieldvalue has no concept of incrementing ntups. Since you are not
appending a tuple like pqAddTuple, or inserting one, you can't increment
ntups in setfieldvalue.
But, you could have a function like PQresultAddEmptyTuple(res) which
would have to be called before you can set field values on a tup_num.
The empty tuple would grow tuples when needed and increment ntups. The
new tuple would be zerod (all NULL values).
....something like below
res = PQmakeResult(...);
for(ntups)
{
PQresultAddEmptyTuple(res); // or PQresultMakeEmptyTuple?
for(nfields)
PQresultSetFieldValue(res, tup_num, field_num, ....);
}
--
Andrew Chernow
eSilo, LLC
every bit counts
http://www.esilo.com/
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