[SERVER-26757] Add featureCompatibilityVersion as a command line option Created: 25/Oct/16  Updated: 31/Oct/16  Resolved: 28/Oct/16

Status: Closed
Project: Core Server
Component/s: Admin
Affects Version/s: None
Fix Version/s: None

Type: Improvement Priority: Minor - P4
Reporter: Joe Drumgoole (Inactive) Assignee: Andy Schwerin
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:

 Description   

Would be great if we could set featureCompatibilityVersion.

1. Its a easy way to configure it.

2. It documents the feature via the -h command.



 Comments   
Comment by Kyle Suarez [ 31/Oct/16 ]

joe.drumgoole, I've added a comment to DOCS-9201 to make sure that the setFeatureCompatibilityVersion command and the general work on Upgrade/Downgrade is appropriately documented.

Comment by Joe Drumgoole (Inactive) [ 31/Oct/16 ]

Somebody should explain what this option is actually doing. Its obviously doing more than just turning on the new 3.4 features. Is it reversible? i.e. can you flick it on and off? What does it do to the database.

Comment by Andy Schwerin [ 28/Oct/16 ]

You cannot reconfigure a replica set from the command line. Also, slowms is not a good analog to featureCompatibilityVersion, because adjusting slowms cannot affect the integrity of the stored data, only the contents of the diagnostic logs.

I agree that for standalone mongod instances, configuring from the command line would be convenient, but the work involved to make it safe is pretty involved and easy to get wrong, so I'm going to close this as "Won't Fix". Thanks for pushing on this, though.

Comment by Joe Drumgoole (Inactive) [ 28/Oct/16 ]

SlowMS is configurable after the fact and is a command line pattern.

You can also reconfigure a replica set and that is also a command line option.

Basically this would consistent with other variables we can set on the command line and reset inside the shell.

Comment by Eric Milkie [ 27/Oct/16 ]

Would you then prohibit allowing someone to subsequently change it with the command, if started with an explicit command line option? Otherwise, you could now end up with a server whose live featureCompatibilityVersion wouldn't match the command line option.

Comment by Joe Drumgoole (Inactive) [ 27/Oct/16 ]

Got it. Still from a developer perspective it would make life easier if single instance mongods could be configured from the command line.

Comment by Eric Milkie [ 27/Oct/16 ]

Sorry, I should have explained. The feature compatibility version affects what data is allowed to be inserted. Therefore, on a sharded or replicated system, it needs to change globally across all of the nodes at the same time. That would be impossible to do with a command line option.

Comment by Joe Drumgoole (Inactive) [ 27/Oct/16 ]

I don't understand this question. Why would it not work on a replicated/sharded system?

Comment by Eric Milkie [ 25/Oct/16 ]

I'm not sure this is a good idea. How would it work on a replicated or sharded system?

Generated at Thu Feb 08 04:13:07 UTC 2024 using Jira 9.7.1#970001-sha1:2222b88b221c4928ef0de3161136cc90c8356a66.