[DOCS-4581] 2.6 covered queries for sharded collections Created: 23/Dec/14  Updated: 12/Jan/15  Resolved: 12/Jan/15

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: v1.3.16, mongodb-2.6

Type: Task Priority: Major - P3
Reporter: Kay Kim (Inactive) Assignee: Kay Kim (Inactive)
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to DOCS-4571 In 2.8 sharded clusters support cover... Closed
is related to DOCS-2473 Covered index queries in sharded envi... Closed
Participants:
Days since reply: 9 years, 5 weeks, 2 days ago

 Description   

queries on sharded collections run against primary can be covered. Behavior seems to have changed starting 2.6.4.

mongos limitation seem unchanged (until 2.8)

MongoDB shell version: 2.6.3
connecting to: 127.0.0.1:27018/test
shardA:PRIMARY> db.foo.find( { a: 1 }, { _id: 0 } ).explain()
{
	"cursor" : "BtreeCursor a_1",
	"isMultiKey" : false,
	"n" : 1,
	"nscannedObjects" : 1,
	"nscanned" : 1,
	"nscannedObjectsAllPlans" : 1,
	"nscannedAllPlans" : 1,
	"scanAndOrder" : false,
	"indexOnly" : false,
 

sharda-265:PRIMARY> db.foo.find( { a: 1}, { a: 1, _id: 0 } ).explain()
{
	"cursor" : "BtreeCursor a_1_b_1",
	"isMultiKey" : false,
	"n" : 1,
	"nscannedObjects" : 0,
	"nscanned" : 1,
	"nscannedObjectsAllPlans" : 0,
	"nscannedAllPlans" : 2,
	"scanAndOrder" : false,
	"indexOnly" : true,
 



 Comments   
Comment by Githook User [ 12/Jan/15 ]

Author:

{u'username': u'kay-kim', u'name': u'kay', u'email': u'kay.kim@10gen.com'}

Message: DOCS-4581 2.6 sharded collection covered queries
Branch: v2.6
https://github.com/mongodb/docs/commit/5da2c0ebd26401a7bcd9ab00452d809ea8642287

Generated at Thu Feb 08 07:48:21 UTC 2024 using Jira 9.7.1#970001-sha1:2222b88b221c4928ef0de3161136cc90c8356a66.