Re: PATCH: Batch/pipelining support for libpq

On Wed, Mar 29, 2017 at 12:40 PM, Vaishnavi Prabakaran
<vaishnaviprabakaran(at)gmail(dot)com> wrote:
> Michael Paquier wrote:
>>Could you as well update src/tools/msvc/vcregress.pl, aka the routine
>>modulescheck so as this new test is skipped. I am sure that nobody
>>will scream if this test is not run on Windows, but the buildfarm will
>>complain if the patch is let in its current state.
>
> Thanks for the finding. Hmm, modulescheck will not pick up test_libpq as
> "subdircheck" will fail for this module(because it does not have
> "sql"/"expected" folders in it) and hence it will be skipped.
> But, Modified "Mkvcbuild.pm" to exclude "test_libpq" module, as this test
> anyways will not be run in Windows and also because it uses linux specific
> APIs(gettimeofday , timersub).

src/port/gettimeofday.c extends things on Windows, and we could
consider to just drop the timing portion for simplicity (except
Windows I am not seeing any platform missing timersub). But that's
just a point of detail. Or we could just drop those tests from the
final patch, and re-implement them after having some psql-level
subcommands. That would far better for portability.

> There are 2 cases tested here:
>
> 1. Example for the case - Using COPY command in batch mode will trigger
> failure. (Specified in documentation)
> Failure can be seen only when processing the copy command's results. That
> is, after dispatching COPY command, server goes into COPY state , but the
> client dispatched another query in batch mode.
>
> Below error messages belongs to this case :
> Error status and message got from server due to COPY command failure are :
> PGRES_FATAL_ERROR ERROR: unexpected message type 0x50 during COPY from
> stdin
> CONTEXT: COPY batch_demo, line 1
>
> message type 0x5a arrived from server while idle

Such messages are really confusing to the user as they refer to the
protocol going out of sync. I would think that something like "cannot
process COPY results during a batch processing" would be cleaner.
Isn't some more error handling necessary in GetCopyStart()?

> Attached the latest code and test patches.

For me the test is still broken:
ok 1 - testlibpqbatch disallowed_in_batch
ok 2 - testlibpqbatch simple_batch
ok 3 - testlibpqbatch multi_batch
ok 4 - testlibpqbatch batch_abort
ok 5 - testlibpqbatch timings
not ok 6 - testlibpqbatch copyfailure

Still broken here. I can see that this patch is having enough
safeguards in PQbatchBegin() and PQsendQueryStart(), but this issue is
really pointing out at something...
--
Michael