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/**
* Test that $unionWith's pipeline argument returns the same explain as an equivalent normal
* pipeline.
* @tags: [
* do_not_wrap_aggregations_in_facets,
* ]
*/
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // arrayEq, documentEq
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.
load("jstests/libs/analyze_plan.js"); // For getAggPlanStage.
const testDB = db.getSiblingDB(jsTestName());
const collA = testDB.A;
collA.drop();
const collB = testDB.B;
collB.drop();
const collC = testDB.C;
collC.drop();
const docsPerColl = 5;
for (let i = 0; i < docsPerColl; i++) {
assert.commandWorked(collA.insert({a: i, val: i, groupKey: i}));
assert.commandWorked(collB.insert({b: i, val: i * 2, groupKey: i}));
assert.commandWorked(collC.insert({c: i, val: 10 - i, groupKey: i}));
}
function getUnionWithStage(explain) {
if (explain.splitPipeline != null) {
// If there is only one shard, the whole pipeline will run on that shard.
const subAggPipe = explain.splitPipeline === null ? explain.shards["shard-rs0"].stages
: explain.splitPipeline.mergerPart;
for (let i = 0; i < subAggPipe.length; i++) {
const stage = subAggPipe[i];
if (stage.hasOwnProperty("$unionWith")) {
return stage;
}
}
} else {
return getAggPlanStage(explain, "$unionWith");
}
}
function buildErrorString(unionExplain, realExplain, field) {
const toString = e => typeof e !== 'string' ? tojson(e) : e;
return "Explains did not match in field " + field + ". Union:\n" + toString(unionExplain) +
"\nRegular:\n" + toString(realExplain);
}
function docEqWithIgnoredFields(union, regular) {
return documentEq(union, regular, false /* verbose */, null /* valueComparator */, [
"executionTimeMillis",
"executionTimeMillisEstimate",
"saveState",
"restoreState",
"works",
"needTime",
]);
}
function assertExplainEq(unionExplain, regularExplain) {
const unionStage = getUnionWithStage(unionExplain);
assert(unionStage);
const unionSubExplain = unionStage.$unionWith.pipeline;
if (FixtureHelpers.isMongos(testDB)) {
const splitPipe = unionExplain.splitPipeline;
if (splitPipe === null) {
assert.eq(unionSubExplain.splitPipeline,
regularExplain.splitPipeline,
buildErrorString(unionSubExplain, regularExplain, "splitPipeline"));
} else {
assert(
docEqWithIgnoredFields(unionSubExplain.splitPipeline, regularExplain.splitPipeline),
buildErrorString(unionSubExplain, regularExplain, "splitPipeline"));
}
assert.eq(unionSubExplain.mergeType,
regularExplain.mergeType,
buildErrorString(unionSubExplain, regularExplain, "mergeType"));
assert(docEqWithIgnoredFields(unionSubExplain.shards, regularExplain.shards),
buildErrorString(unionSubExplain, regularExplain, "shards"));
} else {
if ("executionStats" in unionSubExplain[0].$cursor) {
const unionSubStats =
unionStage.$unionWith.pipeline[0].$cursor.executionStats.executionStages;
const realStats = regularExplain.executionStats.executionStages;
assert(docEqWithIgnoredFields(unionSubStats, realStats),
buildErrorString(unionSubStats, realStats));
} else {
// Tolerate different values for the "NOW" slot when comparing explain output.
const toString = e => tojson(e).replace(/^.* NOW = s[0-9]+ \([0-9]+\).*$/gm, "");
const realExplain = regularExplain.stages;
assert(toString(unionSubExplain) == toString(realExplain),
buildErrorString(toString(unionSubExplain), toString(realExplain)));
}
}
}
function testPipeline(pipeline) {
let unionResult = collA.aggregate([{$unionWith: {coll: collB.getName(), pipeline: pipeline}}],
{explain: true});
let queryResult = collB.aggregate(pipeline, {explain: true});
assertExplainEq(unionResult, queryResult);
}
testPipeline([{$addFields: {bump: true}}]);
testPipeline([{$group: {_id: "$groupKey", sum: {$sum: "$val"}}}]);
testPipeline([{$group: {_id: "$groupKey", sum: {$sum: "$val"}}}, {$addFields: {bump: true}}]);
testPipeline([{$unionWith: {coll: collC.getName()}}]);
testPipeline([{$unionWith: {coll: collC.getName(), pipeline: [{$addFields: {bump: true}}]}}]);
testPipeline([
{$project: {firstProj: false}},
{$group: {_id: "$groupKey", sum: {$sum: "$val"}}},
{$match: {_id: 2}}
]);
testPipeline([{$limit: 3}, {$sort: {_id: 1}}, {$addFields: {bump: true}}]);
testPipeline([{
$addFields: {
value: {
$function: {
body: function(base, pow) {
return Math.pow(base, pow);
},
args: [2, 3],
lang: "js"
}
}
}
}]);
// Ensure that both agg with the explain argument and the explain command work.
assert.commandWorked(testDB.runCommand({
aggregate: collA.getName(),
pipeline: [{$unionWith: collB.getName()}],
cursor: {},
explain: true
}));
assert.commandWorked(testDB.runCommand({
explain: {
aggregate: collA.getName(),
pipeline: [{$unionWith: collB.getName()}],
cursor: {},
}
}));
// Ensure that $unionWith can still execute explain if followed by a stage that calls dispose().
let result = assert.commandWorked(testDB.runCommand({
explain: {
aggregate: collA.getName(),
pipeline: [{$unionWith: collB.getName()}, {$limit: 1}],
cursor: {},
}
}));
// Test that execution stats inner cursor is populated.
result = collA.explain("executionStats").aggregate([{"$unionWith": collB.getName()}]);
assert.commandWorked(result);
let expectedResult = collB.explain("executionStats").aggregate([]);
assert.commandWorked(expectedResult);
let unionStage = getUnionWithStage(result);
assert(unionStage, result);
if (FixtureHelpers.isMongos(testDB)) {
assert(docEqWithIgnoredFields(expectedResult.shards, unionStage.$unionWith.pipeline.shards),
buildErrorString(unionStage, expectedResult));
// TODO SERVER-50597 Fix unionWith nReturned stat in sharded cluster
// assert.eq(unionStage.nReturned, docsPerColl, unionStage);
} else {
assert.eq(unionStage.nReturned, docsPerColl * 2, unionStage);
assert.eq(unionStage.$unionWith.pipeline[0].$cursor.executionStats.nReturned,
docsPerColl,
unionStage);
}
// Test explain with executionStats when the $unionWith stage doesn't need to read from it's
// sub-pipeline.
result = collA.explain("executionStats").aggregate([{"$unionWith": collB.getName()}, {$limit: 1}]);
assert.commandWorked(result);
unionStage = getUnionWithStage(result);
assert(unionStage, result);
if (!FixtureHelpers.isSharded(collB)) {
assert.eq(unionStage.nReturned, 1, unionStage);
assert.eq(unionStage.$unionWith, {coll: "B", pipeline: []}, unionStage);
}
// Test explain with executionStats when the $unionWith stage partially reads from it's
// sub-pipeline.
result = collA.explain("executionStats")
.aggregate([{"$unionWith": collB.getName()}, {$limit: docsPerColl + 1}]);
assert.commandWorked(result);
unionStage = getUnionWithStage(result);
assert(unionStage, result);
if (!FixtureHelpers.isSharded(collB)) {
assert.eq(unionStage.nReturned, docsPerColl + 1, unionStage);
// TODO SERVER-50597 Fix the executionStats of $unionWith sub-pipeline, the actual result should
// be 1 instead of docsPerColl.
assert.eq(unionStage.$unionWith.pipeline[0].$cursor.executionStats.nReturned,
docsPerColl,
unionStage);
}
// Test an index scan.
const indexedColl = testDB.indexed;
assert.commandWorked(indexedColl.createIndex({val: 1}));
indexedColl.insert([{val: 0}, {val: 1}, {val: 2}, {val: 3}]);
result = collA.explain("executionStats").aggregate([
{$unionWith: {coll: indexedColl.getName(), pipeline: [{$match: {val: {$gt: 2}}}]}}
]);
expectedResult = indexedColl.explain("executionStats").aggregate([{$match: {val: {$gt: 2}}}]);
assertExplainEq(result, expectedResult);
// Test a nested $unionWith which itself should perform an index scan.
testPipeline([{$unionWith: {coll: indexedColl.getName(), pipeline: [{$match: {val: {$gt: 0}}}]}}]);
})();
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