Is it possible to pipe an "incoming" SELECT stream into an "outgoing" INSERT stream?

[runeksvendsen]

I'm in need of:

1. Streaming the output of a SELECT to Haskell
2. Mapping over the stream in Haskell
3. Piping the mapped stream into an INSERT

Is this possible? If so, how do I do it?

If no, please mark this issue as a feature request.

[ocharles]

You probably want https://hackage.haskell.org/package/streaming-postgresql-simple-0.2.0.5/docs/Database-PostgreSQL-Simple-Streaming.html#v:copyIn. It's been a long time since I worked on this library though so that's probably the most help I can provide initially.

[runeksvendsen]

@ocharles thank you for the advice.

For what it's worth, I ended up using fold from postgresql-simple: https://hackage.haskell.org/package/postgresql-simple-0.6.5/docs/Database-PostgreSQL-Simple.html#v:fold

The copyIn functions seems too low level for my needs (streaming raw ByteStrings without parsing into rows).

[ocharles]

If you are ok either collecting all rows and doing a single insert or doing one insert per row that will work well, yep