[SERVER-30088] Refresh the in-memory metadata cache on secondaries when invalidated by a primary metadata change Created: 11/Jul/17  Updated: 14/Jul/17  Resolved: 14/Jul/17

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

Type: Task Priority: Major - P3
Reporter: Dianna Hohensee (Inactive) Assignee: Dianna Hohensee (Inactive)
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Sprint: Sharding 2017-08-21
Participants:

 Description   

The current secondary behavior is just to invalidate the secondary's metadata so that the next request to the secondary causes an in-memory refresh. Refreshes require contacting the shard primary, in case the primary is not up to date either and must refresh from the config servers.

A secondary that has the up to date metadata persisted, but hasn't serviced requests in a long while so the up to date metadata hasn't been loaded into memory, can get stuck when it receives a request while either there is no primary or the primary cannot be contacted. To alleviate this situation, we will proactive reload the in-memory cache on receipt of metadata updates. This is a performance improvement.



 Comments   
Comment by Dianna Hohensee (Inactive) [ 14/Jul/17 ]

Closing as won't fix. We decided to do SERVER-30148, which makes this change obsolete.

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