[DOCS-7300] concurrency docs page needs improvement Created: 29/Feb/16  Updated: 11/Jan/17  Resolved: 29/Feb/16

Status: Closed
Project: Documentation
Component/s: None
Affects Version/s: None
Fix Version/s: 01112017-cleanup

Type: Task Priority: Major - P3
Reporter: Dwight Merriman Assignee: Unassigned
Resolution: Duplicate Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Duplicate
duplicates DOCS-7268 audit faq: Concurrency Closed
Participants:
Days since reply: 7 years, 50 weeks, 2 days ago

 Description   

https://docs.mongodb.org/manual/faq/concurrency/

This page I think has became quite confusing over many iterations as releases have gone by. A lot of the content is about mmap but mmap is not hte default storage engine anymore.

Further the WiredTiger section itself says:

For most read and write operations, WiredTiger uses optimistic concurrency control. WiredTiger uses only intent locks at the global, database and collection levels. When the storage engine detects conflicts between two operations, one will incur a write conflict causing MongoDB to transparently retry that operation.
Some global operations, typically short lived operations involving multiple databases, still require a global “instance-wide” lock. Some other operations, such as dropping a collection, still require an exclusive database lock.

It would be easy for the reader to infer from reading this that there is no document level concurrency with WildTiger.

Some mention of pluggable storage engines right at the top might be helpful.



 Comments   
Comment by Kay Kim (Inactive) [ 29/Feb/16 ]

Agree wholeheartedly. We started to audit and rewrite the various FAQ's. We've hit 3 of them already and this and the remaining 5 are slated to undergo a thorough audit and rewrite.

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