[WIP] WITH RECURSIVE support

[jordaaash]

New feature and fix for #1755

I'm testing this out and haven't settled on the API yet, so I'm opening this for feedback.

[elhigu]

Thanks for the PR!

Btw. there is currently also couple of bugs in the original .with statement. For example

.with('name', knex('table').update({ a: 1 })); // doesn't work, one has to use knex.raw() for a workaround
.with('name', knex.raw('??', [knex('table').update({ a: 1 })])); // this works, but is ugly
.with('name', builder => builder.table('table').update({ a: 1 })) // creates some invalid select query instead of update

I would be super happy if those could be fixed too with this PR 👍

About this PR I like the API, but with brief look implementation did seem pretty much copy-paste. Could there be more codesharing between normal .with and .withRecursive?

And could those dialect, that doesn't support .withRecursive throw an error?

Generally I think this looks good and is very welcome feature!

[jordaaash]

Hmm, I'm not sure I'm the best candidate to roll CTE updates into this. I don't use them for anything, and I'm not familiar with support for them or their issues (within Knex or any RDBMS).

A cursory reading of the Postgres docs suggests to me that implementation to support them would be complicated:

Recursive self-references in data-modifying statements are not allowed.
~ https://www.postgresql.org/docs/9.6/static/queries-with.html

I want to limit the scope of this to allowing recursive selects in RDBMSs that support them, so I'll research that.

And, you're right that this PR is totally a copy-paste job at the moment :)
I'll refactor.

One thing that this PR doesn't support yet is the use of recursive functions like

WITH RECURSIVE foo(bar, baz) AS (...)

because it wraps the CTE alias e.g. "foo(bar, baz)" which will throw an error. Depending on how the implementation is changed to support them, it may diverge from plain WITH a bit.

[elhigu]

I'll be fixing the bugs I mentioned #2218 (comment), so only some refactoring and documentation would be needed for this.

[timhuff]

@elhigu Any update on the status of this? Dealing with some graph heavy db design and it'd be pretty nice to have. Let me know if I can lend a hand.

[elhigu]

@timhuff if you can take over finishing this it would be great 👍

[kibertoad]

@timhuff Any chance you could still finish this?

[timhuff]

@kibertoad Unfortunately my schedule doesn't currently permit me to work on this. Perhaps here in a few weeks but for the moment I'm booked solid.

[kibertoad]

I'll refactor and document this.

[kibertoad]

Superseded by #2889