[SERVER-35967] $sample with explain(true) hangs - MongoDB Jira

XML

Word

Printable

JSON

Steps To Reproduce:

Hide

db.c.drop()

for (i = 0; i < 1000; i++ ) { db.c.insertOne({size:1})}

db.c.explain(true).aggregate({$sample: {size: 10}})

Show

db.c.drop() for (i = 0; i < 1000; i++ ) { db.c.insertOne({size:1})} db.c.explain(true).aggregate({$sample: {size: 10}})

Observed in v3.6. Unable to reproduce on v3.4.

$sample command never returns when run with explain(true). db.currentOps() shows:

"planSummary": "MULTI_ITERATOR",

"numYields": 18619890,

numYields continuously increases.

is related to

SERVER-29421 Aggregation executionStats or allPlansExecution explain modes behave incorrectly with $limit

SERVER-35973 Explain execution stats for $sample are not reported correctly

SERVER-19758 Add "executionStats" and "allPlansExecution" explain modes to aggregation explain

Participants:: David Storch, Githook User, Ian Boros, Josef Ahmad, Ramon Fernandez Marina