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/**
* Test to verify the behaviour of find, count, distinct operations in the presence of compound
* hashed indexes.
*
* @tags: [requires_fcv_44]
*/
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // For arrayEq().
load("jstests/libs/analyze_plan.js"); // For assertStagesForExplainOfCommand().
const coll = db.hashed_index_queries;
coll.drop();
for (let i = 0; i < 100; i++) {
assert.commandWorked(assert.commandWorked(
coll.insert({a: i, b: {subObj: "str_" + (i % 13)}, c: NumberInt(i % 10)})));
assert.commandWorked(coll.insert({a: i, b: (i % 13), c: NumberInt(i % 10)}));
}
/**
* Runs find command with the 'filter' and validates that the output returned matches
* 'expectedOutput'. Also runs explain() command on the same find command and validates that all
* the 'expectedStages' are present in the plan returned.
*/
function validateFindCmdOutputAndPlan({filter, expectedStages, expectedOutput}) {
const cmdObj = {find: coll.getName(), filter: filter, projection: {_id: 0}};
if (expectedOutput) {
const res = assert.commandWorked(coll.runCommand(cmdObj));
const ouputArray = new DBCommandCursor(coll.getDB(), res).toArray();
// We ignore the order since hashed index order is not predictable.
assert(arrayEq(expectedOutput, ouputArray), ouputArray);
}
assertStagesForExplainOfCommand({coll: coll, cmdObj: cmdObj, expectedStages: expectedStages});
}
/**
* Runs count command with the 'filter' and validates that the output returned matches
* 'expectedOutput'. Also runs explain() command on the same count command and validates that all
* the 'expectedStages' are present in the plan returned.
*/
function validateCountCmdOutputAndPlan({filter, expectedStages, expectedOutput}) {
const cmdObj = {count: coll.getName(), query: filter};
if (expectedOutput) {
const res = assert.commandWorked(coll.runCommand(cmdObj));
assert.eq(res.n, expectedOutput);
}
assertStagesForExplainOfCommand({coll: coll, cmdObj: cmdObj, expectedStages: expectedStages});
}
/**
* Tests for 'find' operation when hashed field is prefix.
*/
assert.commandWorked(coll.createIndex({b: "hashed", c: -1}));
// Verify that index is not used for a range query on a hashed field.
validateFindCmdOutputAndPlan({filter: {b: {$gt: 10, $lt: 12}}, expectedStages: ["COLLSCAN"]});
// Verify that index is not used for a query on a hashed field's sub-object.
validateFindCmdOutputAndPlan({filter: {"b.subObj": "str_10"}, expectedStages: ["COLLSCAN"]});
// Verify that index is used for a query on a hashed field.
validateFindCmdOutputAndPlan({
filter: {b: {subObj: "str_11"}},
expectedOutput: [
{a: 11, b: {subObj: "str_11"}, c: 1},
{a: 24, b: {subObj: "str_11"}, c: 4},
{a: 37, b: {subObj: "str_11"}, c: 7},
{a: 50, b: {subObj: "str_11"}, c: 0},
{a: 63, b: {subObj: "str_11"}, c: 3},
{a: 76, b: {subObj: "str_11"}, c: 6},
{a: 89, b: {subObj: "str_11"}, c: 9},
],
expectedStages: ["IXSCAN", "FETCH"],
});
/**
* Tests for 'find' operation when hashed field is not a prefix.
*/
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.createIndex({a: 1, b: "hashed", c: -1}));
// Verify $in query can use point interval bounds on hashed fields and non-hashed fields.
validateFindCmdOutputAndPlan({
filter:
{a: {$in: [38, 37]}, b: {$in: [{subObj: "str_12"}, {subObj: "str_11"}]}, c: {$in: [7, 8]}},
expectedOutput: [{a: 37, b: {subObj: "str_11"}, c: 7}, {a: 38, b: {subObj: "str_12"}, c: 8}],
expectedStages: ["IXSCAN", "FETCH"]
});
// Verify that a range query on a non-hashed prefix field can use index.
validateFindCmdOutputAndPlan({
filter: {a: {$gt: 25, $lt: 29}, b: 0},
expectedOutput: [{a: 26, b: 0, c: 6}],
expectedStages: ["IXSCAN", "FETCH"]
});
/**
* Tests for 'count' operation when hashed field is prefix.
*/
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.createIndex({b: "hashed", a: 1}));
// Verify that index is not used for a range query on a hashed field.
validateCountCmdOutputAndPlan(
{filter: {b: {$gt: 10, $lt: 12}}, expectedOutput: 7, expectedStages: ["COLLSCAN"]});
// Verify that index is used for a query on a hashed field.
validateCountCmdOutputAndPlan(
{filter: {b: {subObj: "str_10"}}, expectedOutput: 7, expectedStages: ["IXSCAN", "FETCH"]});
/**
* Tests for 'count' operation when hashed field is not a prefix.
*/
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.createIndex({a: 1, b: "hashed", c: -1}));
// Verify that range query on a non-hashed prefix field can use index.
validateCountCmdOutputAndPlan({
filter: {a: {$gt: 25, $lt: 29}, b: 0},
expectedOutput: 1,
expectedStages: ["IXSCAN", "FETCH"]
});
/**
* Tests for 'distinct' operation when hashed field is not a prefix.
*/
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.createIndex({a: -1, b: "hashed", c: 1}));
// 'distinct' on non-hashed prefix fields cannot use DISTINCT_SCAN.
assert.eq(100, coll.distinct("a").length);
let plan = coll.explain("executionStats").distinct("a");
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
// 'distinct' on non-prefix fields cannot use index.
assert.eq(26, coll.distinct("b").length);
plan = coll.explain("executionStats").distinct("b");
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
assert.eq(10, coll.distinct("c").length);
plan = coll.explain("executionStats").distinct("c");
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
// 'distinct' with query predicate can use index for the query part.
assert.eq([2], coll.distinct("c", {a: 12, b: {subObj: "str_12"}}));
plan = coll.explain("executionStats").distinct("c", {a: 12, b: {subObj: "str_12"}});
assert(isIxscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
assert(planHasStage(db, plan.queryPlanner.winningPlan, "FETCH"), plan.queryPlanner.winningPlan);
/**
* Tests for 'distinct' operation when hashed field is a prefix.
*/
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.createIndex({b: "hashed", c: 1}));
// 'distinct' on hashed prefix field cannot use index.
assert.eq(26, coll.distinct("b").length);
plan = coll.explain("executionStats").distinct("b");
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
// 'distinct' with query predicate can use index for the query part.
assert.eq([1], coll.distinct("b", {b: 1}));
plan = coll.explain("executionStats").distinct("b", {b: 1});
assert(isIxscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
assert(planHasStage(db, plan.queryPlanner.winningPlan, "FETCH"), plan.queryPlanner.winningPlan);
// 'distinct' with query predicate cannot use index when query cannot use index.
assert.eq([5], coll.distinct("b", {b: {$lt: 6, $gt: 4}}));
plan = coll.explain("executionStats").distinct("b", {b: {$lt: 6, $gt: 4}});
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
// 'distinct' with query predicate can use index for the query part.
assert.eq([2], coll.distinct("c", {a: 12, b: 12}));
plan = coll.explain("executionStats").distinct("c", {a: 12, b: 12});
assert(isIxscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
assert(planHasStage(db, plan.queryPlanner.winningPlan, "FETCH"), plan.queryPlanner.winningPlan);
// 'distinct' on non-prefix fields cannot use index.
assert.eq(10, coll.distinct("c").length);
plan = coll.explain("executionStats").distinct("c");
assert(isCollscan(db, plan.queryPlanner.winningPlan), plan.queryPlanner.winningPlan);
})();
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