[DOCS-11954] Ambiguous terminology is used to describe locking during background index builds Created: 10/Aug/18  Updated: 30/Oct/23  Resolved: 13/Mar/23

Status: Closed
Project: Documentation
Component/s: Server
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Bug Priority: Minor - P4
Reporter: Dmitry Ryabtsev Assignee: Ravind Kumar (Inactive)
Resolution: Gone away Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:
Days since reply: 47 weeks, 2 days ago

 Description   

----------------------------

Original Description

Here in the documentation we currently say that:

  • A foreground index build on a primary requires a DB lock. It replicates as a foreground index build on replica set secondaries, and the replication worker takes a global DB lock that queues reads and writes to all databases on the indexing server.
  • A background index build on a primary replicates as background index builds on secondaries. The replication worker does not take a global DB lock, and secondary reads are not affected.

It is not entirely clear what kind of lock we mean here as (using db.currentOp output as a reference) there are three main types of locks:

  • Global
  • Database
  • Collection

There is no "global DB lock". We should clarify what kind of lock (should be just "global lock", I'm guessing) we are talking about here exactly.

"db.currentOp()"

Show all

			"lockStats" : {
				"Global" : {
					"acquireCount" : {
						"w" : NumberLong(35935)
					},
					"acquireWaitCount" : {
						"w" : NumberLong(16)
					},
					"timeAcquiringMicros" : {
						"w" : NumberLong(1971869)
					}
				},
				"Database" : {
					"acquireCount" : {
						"w" : NumberLong(35935),
						},
					"acquireWaitCount" : {
						"w" : NumberLong(1),
						"W" : NumberLong(1)
					},
					"timeAcquiringMicros" : {
						"w" : NumberLong(27),
						"W" : NumberLong(137317)
					}
				},
				"Collection" : {
					"acquireCount" : {
						"w" : NumberLong(35935)
					}
				}

----------------------------

Description

Scope of changes (files that need work and how much)

Impact to other docs outside of this product

MVP (work and date?)

Resources (e.g. Scope Docs, Invision)



 Comments   
Comment by Ashley Brown [ 13/Mar/23 ]

Hi, we're closing this ticket because we believe the ask no longer applies in the current documentation. If you believe this is an error, please reopen the ticket with a comment explaining why and we'll take a look. Thanks!

Comment by Dmitry Ryabtsev [ 10/Aug/18 ]

The main concern is basically that it could be read as there should not be a Database lock (which is not true).

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