Re: PATCH: Batch/pipelining support for libpq

Craig Ringer wrote:

> I think it's mostly of interest to app authors and driver developers
> and that's what it's aimed at. pg_restore could benefit a lot too.

Wouldn't pgbench benefit from it?
It was mentioned some time ago [1], in relationship to the
\into construct, how client-server latency was important enough to
justify the use of a "\;" separator between statements, to send them
as a group.

But with the libpq batch API, maybe this could be modernized
with meta-commands like this:
\startbatch
...
\endbatch
which would essentially call PQbeginBatchMode() and PQsendEndBatch().
Inside the batch section, collecting results would be interleaved
with sending queries.
Interdepencies between results and subsequent queries could
be handled or ignored, depending on how sophisticated we'd want
this.

This might also draw more users to the batch API, because
it would make it easier to check how exactly it affects
the performance of specific sequences of SQL statements to be
grouped in a batch.
For instance it would make sense for programmers to benchmark mock-ups
of their code with pgbench with/without batching, before embarking on
adapting it from blocking mode to asynchronous/non-blocking mode.

[1]
https://www.postgresql.org/message-id/alpine.DEB.2.20.1607140925400.1962%40sto

Best regards,
--
Daniel Vérité
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