Processing some queries in batches and new EXPLAIN command

[elcct]

See my comments for #294 and #263

[pauldix]

would be great to move this into a configuration option as you mentioned before

[elcct]

I have added it.

It is now point-batch-size under [leveldb] section in config.toml

[jvshahid]

Thanks @elcct for your contribution. We're really excited about the new features that you added in this pull request. Couple of things that will make it extremely easy for us to merge your changes in the future (I'll put these guidelines in a commiters readme file):

1. Add tests for the changes you're putting in. This will make it easy for us to review the changes and avoid regressions in the future. It's ok for this pr, i'll just add the test
2. Each pull request should contain one feature or bug fix, in this case you have the explain query and partial fix for Engine interface should change to take batches of points #294 combined in the same pr.
3. Commits should be squashed, each feature or bug fix should go in one commit to make it easier to view the history of the project and revert changes (not that we'll every want to do that)
4. You should open pull requests from a branch not from master. Otherwise changes that go in your repo's master will show up in old pull requests that you opened.
5. Normally we'd ask contributors to rebase their branches on top of current master. In this case, I felt master has so many changes that it'd be more appropriate if we did the rebase. See https://github.com/influxdb/influxdb/tree/pr-318 for the squashed commits of the two features that were on your branch.

If you have any questions or comments feel free to tell us.

Cheers,

[elcct]

Thank you. I am sorry for the trouble, next time I will follow those guidelines.

[jvshahid]

I merged my branch which included some tests and bug fixes. I encourage you to take a look and verify that I didn't do something stupid. doing git diff dbe76df..7bda031 should give you the changes that i just merged into master.

Thanks again for your contribution.

[elcct]

Great, i should take a look during the weekend.