You are viewing a plain text version of this content. The canonical link for it is here.

Posted to notifications@couchdb.apache.org by GitBox <gi...@apache.org> on 2020/03/20 23:57:25 UTC

[GitHub] [couchdb] chewbranca opened a new pull request #2690: Fix create db options on secondary shard creation

chewbranca opened a new pull request #2690: Fix create db options on secondary shard creation
URL: https://github.com/apache/couchdb/pull/2690

<!-- Thank you for your contribution!

Please file this form by replacing the Markdown comments
with your text. If a section needs no action - remove it.

Also remember, that CouchDB uses the Review-Then-Commit (RTC) model
of code collaboration. Positive feedback is represented +1 from committers
and negative is a -1. The -1 also means veto, and needs to be addressed
to proceed. Once there are no objections, the PR can be merged by a
CouchDB committer.

See: http://couchdb.apache.org/bylaws.html#decisions for more info. -->

## Overview

This is a continuation of the work in https://github.com/apache/couchdb/pull/2672 to fix issues around secondary shard creation when nodes re-enter a cluster after a database was created while the node was down (or potentially in maintenance mode).

This PR introduces logic to handle the following four scenarios while opening a db in context of `fabric_rpc` and `mem3_rpc`:

1) the db already exists
- just return the db as normal
2) the db does not exist locally, but the dbs db doc with db create options is present
- load the db create options and create the local shard
3) the db does not exist locally but it's not a sharded database
- just create the local db as expected
4) the db does not exist locally, it's a sharded database, and the dbs db doc is not present
- throw an error and prevent creating the db with incomplete settings

This PR changes the behavior of scenario 2) by loading the appropriate config and creating the db with the desired parameters, and of scenario 4) by no longer allowing the db to be created inappropriately.

For scenario three, I've taken the approach of not loading config as a non sharded db won't have a dbs db doc. In particular here, we want to properly handle updates to internal dbs like `_dbs` and also `sys_dbs` like `_users`.

Another open item here is the merging of the db create options and the provided options. Right now, I'm just doing `DbOpts ++ Opts` basically, but I wrote a functions `opts_merge/{2,3}` that will merge two proplists, prioritizing the first list of items, and supports atoms. It's... a bit gnarly, and I'm not convinced we should use it. So we need to figure out what to do with the options lists here, but I _think_ we might be ok just combining the two.

While in the general neighborhood, I took the opportunity to de-duplicate some of the shards_db config lookups as well. I've isolated those changes to a dedicated commit.

## Testing recommendations

This needs more testing. I've got a WIP commit for adding a test suite here that is not yet complete. I figured it was worthwhile to get this PR out for feedback while continuing to work on the tests.

## Related Issues or Pull Requests

https://github.com/apache/couchdb/pull/2672

## Checklist

- [ ] Code is written and works correctly
- [ ] Changes are covered by tests
- [ ] Any new configurable parameters are documented in `rel/overlay/etc/default.ini`
- [ ] A PR for documentation changes has been made in https://github.com/apache/couchdb-documentation

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org

With regards,
Apache Git Services