Support binary format

[bitonic]

libpq supports a binary interchange format -- see https://www.stackage.org/haddock/lts-17.11/postgresql-libpq-0.9.4.3/Database-PostgreSQL-LibPQ.html#v:execParams .

We recently ran into some performance issues, and I suspect that avoiding to escape the results of queries would greatly help. However I think opaleye and even postgresql-simple do not support the binary format -- so I didn't go very far.

[tomjaguarpaw]

Interesting. I am not familiar with this. Is it just the results of the queries you want to be in binary format, or also the query itself. From the API you linked it looks like only the query parameters can be in binary format, not the query itself. Is that right?

[tomjaguarpaw]

If you can give me an example of how to use the LibPQ API then perhaps I can tell you how to get Opaleye to use it. However, at the moment Opaleye leans very heavily on the parsers in postgresql-simple. It's possible that we would have to rewrite a lot of parsing code.

[bitonic]

My understanding is that it is possible to get results in binary format, see for example https://www.postgresql.org/docs/9.6/libpq-example.html#LIBPQ-EXAMPLE-3 .

However, I have not investigated how to execute a similar query in Haskell yet. I'll update this issue if I get to it, although the performance problems I mentioned are currently not so critical, and so it probably won't happen very soon.

[tomjaguarpaw]

OK, it's good to have this issue here as a reminder that it would be a useful thing to implement. I don't currently have the time to drive this forward myself, but if you discover how to fit all the pieces together I can help you plug it into Opaleye.

(Having said that, it's possible that this should go into postgresql-simple instead, in which case it would fit into Opaleye naturally.)

[ParetoOptimalDev]

Would it be possible to re-use parts from hasql for this?

It uses the binary interface.

[tomjaguarpaw]

Theoretically we could just add a hasql backend. That's what rel8 does.