Fix for high concurrency issue

[billwashere]

This pull request does two changes

1) Changes the datatype on the ops and snapshots tables to JSONB

2) Attempts to resolve the high concurrency issue but committing the snapshot and operation in one transaction

[billwashere]

Hi @nornagon I've split out pooling into a seperate change - https://github.com/share/sharedb-postgres/pull/5

[billwashere]

I've this pull request with the required changes.

Additionally

1. Commit no longer requires jsonb, it works fine without it
2. On close, the connection pool drains

[jasoniangreen]

Hey @billwashere and @nornagon, what is the state of this? Do you need any help?

[billwashere]

I believe that it working correctly, however due to the fact that it is such a big change more testing may be required (I'll leave how much testing to @nornagon).

If you want to try it out and see if you can break it, that would be great.

[nornagon]

Would you be able to rebase this on top of master? It looks like mostly minor conflicts. Also retitle the PR, since this is now only addressing the concurrency issue.

Thanks! If this is reported working for a few people, I'm happy to merge it (at least, once I sit down and actually understand what's going on with the query...). The code as it is is not particularly well tested, so new untested code at least won't be a regression, but it'd be great to have better test coverage! especially cool would be if you could construct a test that fails with the old code but passes with the new.

[ianberdin]

@billwashere can you merge this to master and update npm package?

[Utwo]

@billwashere can you merge this to master and update npm package?

I think you can use this package: https://github.com/plotdb/sharedb-postgres

[nornagon]

if @zbryikt or someone wants to take over maintenance of this repo, I'm happy to grant access.