Files
mongo/jstests/aggregation/sources/project/remove_redundant_projects.js
Zac 591928c619 SERVER-108478 JS formatted by prettier and remove clang-format (#39656)
GitOrigin-RevId: 6c8f6aded47f260aa4f7c231b17dae3302cb1e04
2025-08-21 17:27:09 +00:00

235 lines
8.6 KiB
JavaScript

// Tests that the aggregation pipeline correctly coalesces a $project stage at the front of the
// pipeline that can be covered by a normal query.
// @tags: [
// do_not_wrap_aggregations_in_facets,
// requires_pipeline_optimization,
// # During fcv upgrade/downgrade the engine might not be what we expect.
// cannot_run_during_upgrade_downgrade,
// ]
import {documentEq, orderedArrayEq} from "jstests/aggregation/extras/utils.js";
import {
getPlanStages,
getWinningPlanFromExplain,
isAggregationPlan,
isQueryPlan,
} from "jstests/libs/query/analyze_plan.js";
import {
checkSbeCompletelyDisabled,
checkSbeFullyEnabled,
checkSbeRestrictedOrFullyEnabled,
} from "jstests/libs/query/sbe_util.js";
let coll = db.remove_redundant_projects;
coll.drop();
assert.commandWorked(coll.insert({_id: {a: 1, b: 1}, a: 1, c: {d: 1}, e: ["elem1"]}));
let indexSpec = {a: 1, "c.d": 1, "e.0": 1};
const sbeFullyEnabled = checkSbeFullyEnabled(db);
const sbeRestricted = checkSbeRestrictedOrFullyEnabled(db);
/**
* Helper to test that for a given pipeline, the same results are returned whether or not an
* index is present. Also tests whether a projection is absorbed by the pipeline
* ('expectProjectToCoalesce') and the corresponding project stage ('removedProjectStage') does
* not exist in the explain output. When 'expectProjectToCoalesce' is true, the caller should
* specify which projects are expected to coalesce in 'expectedCoalescedProjects'.
*/
function assertResultsMatch({
pipeline = [],
expectProjectToCoalesce = false,
expectedCoalescedProjects = [],
removedProjectStage = null,
index = indexSpec,
pipelineOptimizedAway = false,
} = {}) {
// Add a match stage to ensure index scans are considered for planning (workaround for
// SERVER-20066).
pipeline = [{$match: {a: {$gte: 0}}}].concat(pipeline);
// Once with an index.
assert.commandWorked(coll.createIndex(index));
let explain = coll.explain().aggregate(pipeline);
let resultsWithIndex = coll.aggregate(pipeline).toArray();
// Projection does not get pushed down when sharding filter is used.
if (!explain.hasOwnProperty("shards")) {
let result;
if (pipelineOptimizedAway) {
assert(isQueryPlan(explain), explain);
result = getWinningPlanFromExplain(explain.queryPlanner);
} else {
assert(isAggregationPlan(explain), explain);
result = getWinningPlanFromExplain(explain.stages[0].$cursor.queryPlanner);
}
// Check that $project uses the query system and all expectedCoalescedProjects are
// actually present in explain.
if (expectProjectToCoalesce) {
assert.gte(
expectedCoalescedProjects.length,
1,
"If we expect project to coalesce, there should be at least one such projection in expectedCoalescedProjects " +
tojson(expectedCoalescedProjects),
);
const projects = [
...getPlanStages(result, "PROJECTION_DEFAULT"),
...getPlanStages(result, "PROJECTION_COVERED"),
...getPlanStages(result, "PROJECTION_SIMPLE"),
];
assert.gte(projects.length, 1, explain);
const areAllexpectedCoalescedProjectsPresent = expectedCoalescedProjects.every((coalescedProject) => {
return projects.some((project) => {
return documentEq(project.transformBy, coalescedProject);
});
});
assert(
areAllexpectedCoalescedProjectsPresent,
"There were missing or extra coalesced projects in " +
tojson(expectedCoalescedProjects) +
" with explain " +
tojson(explain),
);
}
if (!pipelineOptimizedAway) {
// Check that $project was removed from pipeline and pushed to the query system.
explain.stages.forEach(function (stage) {
if (stage.hasOwnProperty("$project")) assert.neq(removedProjectStage, stage["$project"], explain);
});
}
}
// Again without an index.
assert.commandWorked(coll.dropIndex(index));
let resultsWithoutIndex = coll.aggregate(pipeline).toArray();
assert(orderedArrayEq(resultsWithIndex, resultsWithoutIndex));
}
// Test that covered projections correctly use the query system for projection and the $project
// stage is removed from the pipeline.
assertResultsMatch({
pipeline: [{$project: {_id: 0, a: 1}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"a": true, "_id": false}],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [{$project: {_id: 0, a: 1}}, {$group: {_id: null, a: {$sum: "$a"}}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"a": true, "_id": false}],
removedProjectStage: {_id: 0, a: 1},
pipelineOptimizedAway: sbeRestricted,
});
assertResultsMatch({
pipeline: [{$sort: {a: -1}}, {$project: {_id: 0, a: 1}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"a": true, "_id": false}],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [{$sort: {a: 1, "c.d": 1}}, {$project: {_id: 0, a: 1}}, {$group: {_id: "$a", a: {$sum: "$a"}}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"a": true, "_id": false}],
removedProjectStage: {_id: 0, a: 1},
pipelineOptimizedAway: sbeRestricted,
});
assertResultsMatch({
pipeline: [{$project: {_id: 0, c: {d: 1}}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"c": {"d": true}, "_id": false}],
pipelineOptimizedAway: true,
});
// Test that projections with renamed fields are removed from the pipeline.
assertResultsMatch({
pipeline: [{$project: {_id: 0, f: "$a"}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"f": "$a", "_id": false}],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [{$project: {_id: 0, a: 1, f: "$a"}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"a": true, "f": "$a", "_id": false}],
pipelineOptimizedAway: true,
});
// Test that uncovered projections are removed from the pipeline.
assertResultsMatch({
pipeline: [{$sort: {a: 1}}, {$project: {_id: 1, b: 1}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"_id": true, "b": true}],
pipelineOptimizedAway: true,
});
// When SBE is not enabled, we end up pushing down a projection which is internally generated by the
// aggregation subsystem's dependency analysis logic.
assertResultsMatch({
pipeline: [{$sort: {a: 1}}, {$group: {_id: "$_id", a: {$sum: "$a"}}}, {$project: {arr: 1}}],
expectProjectToCoalesce: checkSbeCompletelyDisabled(db) || sbeFullyEnabled,
expectedCoalescedProjects: sbeFullyEnabled ? [{"_id": true, "arr": true}] : [{"_id": 1, "a": 1}],
pipelineOptimizedAway: sbeFullyEnabled,
});
// Test that projections with computed fields are removed from the pipeline.
assertResultsMatch({
pipeline: [{$project: {computedField: {$sum: "$a"}}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"_id": true, "computedField": {"$sum": ["$a"]}}],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [{$project: {a: ["$a", "$b"]}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"_id": true, "a": ["$a", "$b"]}],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [{$project: {e: {$filter: {input: "$e", as: "item", cond: {"$eq": ["$$item", "elem0"]}}}}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [
{
"_id": true,
"e": {
"$filter": {"input": "$e", "as": "item", "cond": {"$eq": ["$$item", {"$const": "elem0"}]}},
},
},
],
pipelineOptimizedAway: true,
});
assertResultsMatch({
pipeline: [
{$project: {_id: 0, a: 1}},
{$group: {_id: "$a", c: {$sum: "$c"}, a: {$sum: "$a"}}},
{$project: {_id: 0}},
],
expectProjectToCoalesce: true,
expectedCoalescedProjects: sbeFullyEnabled
? [{"a": true, "_id": false}, {"_id": false}]
: [{"a": true, "_id": false}],
pipelineOptimizedAway: sbeFullyEnabled,
});
// Test that projections on _id with nested fields are removed from pipeline.
indexSpec = {
"_id.a": 1,
a: 1,
};
assertResultsMatch({
pipeline: [{$match: {"_id.a": 1}}, {$project: {"_id.a": 1}}],
expectProjectToCoalesce: true,
expectedCoalescedProjects: [{"_id": {"a": true}}],
index: indexSpec,
pipelineOptimizedAway: true,
removedProjectStage: {"_id.a": 1},
});