Vaishnavi Prabakaran wrote:

> >      while (QbatchQueueProcess(conn)) {
> >        r = PQsetSingleRowMode(conn);
> >        if (r!=1) {
> >           fprintf(stderr, "PQsetSingleRowMode() failed");
> >        }
> >        ..

> Thanks for investigating the problem, and could you kindly explain what
> "next iteration" you mean here? Because I don't see any problem in
> following sequence of calls - PQbatchQueueProcess(),PQsetSingleRowMode()
> , PQgetResult()

I mean the next iteration of the above while statement. Referring
to the doc, that would be the "next batch entry":

  " To get the result of the first batch entry the client must call
   PQbatchQueueProcess. It must then call PQgetResult and handle the
   results until PQgetResult returns null (or would return null if
   called). The result from the next batch entry may then be retrieved
   using PQbatchQueueProcess and the cycle repeated"

Attached is a bare-bones testcase showing the problem.
As it is, it works, retrieving results for three "SELECT 1"
in the same batch.  Now in order to use the single-row
fetch mode, consider adding this:

    r = PQsetSingleRowMode(conn);
    if (r!=1) {
      fprintf(stderr, "PQsetSingleRowMode() failed for i=%d\n", i);

When inserted after the call to PQbatchQueueProcess,
which is what I understand you're saying works for you,
it fails for me when starting to get the results of the 2nd query
and after. 

Best regards,
Daniel Vérité
PostgreSQL-powered mailer:
Twitter: @DanielVerite

Attachment: test-singlerow-batch.c
Description: Binary data

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