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// Cannot implicitly shard accessed collections because queries on a sharded collection are not
// able to be covered when they aren't on the shard key since the document needs to be fetched in
// order to apply the SHARDING_FILTER stage.
// @tags: [
// assumes_unsharded_collection,
// requires_fastcount,
// # The test assumes it is in control of which indexes exist and makes some assertions on explain
// # plans.
// assumes_no_implicit_index_creation,
// ]
(function() {
"use strict";
const t = db["jstests_coveredIndex2"];
t.drop();
// Include helpers for analyzing explain output.
load("jstests/libs/analyze_plan.js");
assert.commandWorked(t.insert({a: 1}));
assert.commandWorked(t.insert({a: 2}));
assert.eq(t.findOne({a: 1}).a, 1, "Cannot find right record");
assert.eq(t.count(), 2, "Not right length");
// use simple index
assert.commandWorked(t.createIndex({a: 1}));
let plan = t.find({a: 1}).explain();
assert(!isIndexOnly(db, getWinningPlan(plan.queryPlanner)),
"Find using covered index but all fields are returned");
plan = t.find({a: 1}, {a: 1}).explain();
assert(!isIndexOnly(db, getWinningPlan(plan.queryPlanner)),
"Find using covered index but _id is returned");
plan = t.find({a: 1}, {a: 1, _id: 0}).explain();
assert(isIndexOnly(db, getWinningPlan(plan.queryPlanner)), "Find is not using covered index");
// add multikey
assert.commandWorked(t.insert({a: [3, 4]}));
plan = t.find({a: 1}, {a: 1, _id: 0}).explain();
assert(!isIndexOnly(db, getWinningPlan(plan.queryPlanner)),
"Find is using covered index even after multikey insert");
}());
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