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// Tests for the $merge stage with whenMatched: "replace" and whenNotMatched: "insert".
// @tags: [assumes_unsharded_collection]
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // For assertErrorCode.
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.isMongos.
const coll = db.merge_replace_insert;
const outColl = db.merge_replace_insert_out;
coll.drop();
outColl.drop();
const nDocs = 10;
for (let i = 0; i < nDocs; i++) {
assert.commandWorked(coll.insert({_id: i, a: i}));
}
// Test that a $merge with whenMatched: "replace" and whenNotMatched: "insert" mode will
// default the "on" fields to "_id".
coll.aggregate(
[{$merge: {into: outColl.getName(), whenMatched: "replace", whenNotMatched: "insert"}}]);
assert.eq(nDocs, outColl.find().itcount());
// Test that $merge will update existing documents that match the "on" fields.
const nDocsReplaced = 5;
coll.aggregate([
{$project: {_id: {$mod: ["$_id", nDocsReplaced]}}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: "_id"
}
}
]);
assert.eq(nDocsReplaced, outColl.find({a: {$exists: false}}).itcount());
// Test $merge with a dotted path "on" fields.
coll.drop();
outColl.drop();
assert.commandWorked(coll.insert([{_id: 0, a: {b: 1}}, {_id: 1, a: {b: 1}, c: 1}]));
assert.commandWorked(outColl.createIndex({"a.b": 1, _id: 1}, {unique: true}));
coll.aggregate([
{$addFields: {_id: 0}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: ["_id", "a.b"]
}
}
]);
assert.eq([{_id: 0, a: {b: 1}, c: 1}], outColl.find().toArray());
// Test that $merge will automatically generate a missing "_id" for the "on" field.
coll.drop();
outColl.drop();
assert.commandWorked(coll.insert({field: "will be removed"}));
assert.doesNotThrow(() => coll.aggregate([
{$replaceRoot: {newRoot: {}}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
}
}
]));
assert.eq(1, outColl.find({field: {$exists: false}}).itcount());
// Test that $merge will automatically generate a missing "_id", and the aggregation succeeds
// with multiple "on" fields.
outColl.drop();
assert.commandWorked(outColl.createIndex({name: -1, _id: 1}, {unique: true, sparse: true}));
assert.doesNotThrow(() => coll.aggregate([
{$replaceRoot: {newRoot: {name: "jungsoo"}}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: ["_id", "name"]
}
}
]));
assert.eq(1, outColl.find().itcount());
// Test that we will not attempt to modify the _id of an existing document if the _id is
// projected away but the "on" field does not involve _id.
coll.drop();
assert.commandWorked(coll.insert({name: "kyle"}));
assert.commandWorked(coll.insert({name: "nick"}));
outColl.drop();
assert.commandWorked(outColl.createIndex({name: 1}, {unique: true}));
assert.commandWorked(outColl.insert({_id: "must be unchanged", name: "kyle"}));
assert.doesNotThrow(() => coll.aggregate([
{$project: {_id: 0}},
{$addFields: {newField: 1}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: "name"
}
}
]));
const outResult = outColl.find().sort({name: 1}).toArray();
const errmsgFn = () => tojson(outResult);
assert.eq(2, outResult.length, errmsgFn);
assert.docEq({_id: "must be unchanged", name: "kyle", newField: 1}, outResult[0], errmsgFn);
assert.eq("nick", outResult[1].name, errmsgFn);
assert.eq(1, outResult[1].newField, errmsgFn);
assert.neq(null, outResult[1]._id, errmsgFn);
// Test that $merge with a missing non-id "on" field fails.
outColl.drop();
assert.commandWorked(outColl.createIndex({missing: 1}, {unique: true}));
assertErrorCode(
coll,
[{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: "missing"
}
}],
51132 // This attempt should fail because there's no field 'missing' in the document.
);
// Test that a replace fails to insert a document if it violates a unique index constraint. In
// this example, $merge will attempt to insert multiple documents with {a: 0} which is not
// allowed with the unique index on {a: 1}.
coll.drop();
assert.commandWorked(coll.insert([{_id: 0}, {_id: 1}]));
outColl.drop();
assert.commandWorked(outColl.createIndex({a: 1}, {unique: true}));
assertErrorCode(
coll,
[
{$addFields: {a: 0}},
{$merge: {into: outColl.getName(), whenMatched: "replace", whenNotMatched: "insert"}}
],
ErrorCodes.DuplicateKey);
// Test that $merge fails if the "on" fields contains an array.
coll.drop();
assert.commandWorked(coll.insert({_id: 0, a: [1, 2]}));
assert.commandWorked(outColl.createIndex({"a.b": 1, _id: 1}, {unique: true}));
assertErrorCode(coll,
[
{$addFields: {_id: 0}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: ["_id", "a.b"]
}
}
],
51132);
coll.drop();
assert.commandWorked(coll.insert({_id: 0, a: [{b: 1}]}));
assertErrorCode(coll,
[
{$addFields: {_id: 0}},
{
$merge: {
into: outColl.getName(),
whenMatched: "replace",
whenNotMatched: "insert",
on: ["_id", "a.b"]
}
}
],
51132);
// Tests for $merge to a database that differs from the aggregation database.
const foreignDb = db.getSiblingDB("merge_replace_insert_foreign");
const foreignTargetColl = foreignDb.out;
const pipelineDifferentOutputDb = [{
$merge: {
into: {
db: foreignDb.getName(),
coll: foreignTargetColl.getName(),
},
whenMatched: "replace",
whenNotMatched: "insert",
}
}];
coll.drop();
assert.commandWorked(coll.insert({_id: 0}));
foreignDb.dropDatabase();
if (!FixtureHelpers.isMongos(db)) {
// Test that $merge implicitly creates a new database when the output collection's database
// doesn't exist.
coll.aggregate(pipelineDifferentOutputDb);
assert.eq(foreignTargetColl.find().itcount(), 1);
} else {
// Implicit database creation is prohibited in a cluster.
let error = assert.throws(() => coll.aggregate(pipelineDifferentOutputDb));
assert.commandFailedWithCode(error, ErrorCodes.NamespaceNotFound);
// Force a creation of the database and collection, then fall through the test below.
assert.commandWorked(foreignTargetColl.insert({_id: 0}));
}
// Insert a new document into the source collection, then test that running the same
// aggregation will replace existing documents in the foreign output collection when
// applicable.
coll.drop();
const newDocuments = [{_id: 0, newField: 1}, {_id: 1}];
assert.commandWorked(coll.insert(newDocuments));
coll.aggregate(pipelineDifferentOutputDb);
assert.eq(foreignTargetColl.find().sort({_id: 1}).toArray(), newDocuments);
}());
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