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// Test that a pipeline with a $lookup stage on a sharded foreign collection may be run on a mongod.
(function() {
load("jstests/noPassthrough/libs/server_parameter_helpers.js"); // For setParameterOnAllHosts.
load("jstests/libs/discover_topology.js"); // For findDataBearingNodes.
const sharded = new ShardingTest({mongos: 1, shards: 2});
setParameterOnAllHosts(
DiscoverTopology.findNonConfigNodes(sharded.s), "internalQueryAllowShardedLookup", true);
assert.commandWorked(sharded.s.adminCommand({enableSharding: "test"}));
sharded.ensurePrimaryShard('test', sharded.shard0.shardName);
const coll = sharded.s.getDB('test').mainColl;
const foreignColl = sharded.s.getDB('test').foreignColl;
const smallColl = sharded.s.getDB("test").smallColl;
const nDocsMainColl = 10;
const nDocsForeignColl = 2 * nDocsMainColl;
for (let i = 0; i < nDocsMainColl; i++) {
assert.commandWorked(coll.insert({_id: i, collName: "mainColl", foreignId: i}));
assert.commandWorked(
foreignColl.insert({_id: 2 * i, key: i, collName: "foreignColl", data: "hello-0"}));
assert.commandWorked(
foreignColl.insert({_id: 2 * i + 1, key: i, collName: "foreignColl", data: "hello-1"}));
}
assert.commandWorked(smallColl.insert({_id: 0, collName: "smallColl"}));
const runTest = function() {
(function testSingleLookupFromShard() {
// Run a pipeline which must be merged on a shard. This should force the $lookup (on
// the sharded collection) to be run on a mongod.
pipeline = [
{
$lookup: {
localField: "foreignId",
foreignField: "key",
from: "foreignColl",
as: "foreignDoc"
}
},
{$_internalSplitPipeline: {mergeType: "anyShard"}}
];
const results = coll.aggregate(pipeline).toArray();
assert.eq(results.length, nDocsMainColl);
for (let i = 0; i < results.length; i++) {
assert.eq(results[i].foreignDoc.length, 2, results[i]);
}
})();
(function testMultipleLookupsFromShard() {
// Run two lookups in a row (both on mongod).
pipeline = [
{
$lookup: {
localField: "foreignId",
foreignField: "key",
from: "foreignColl",
as: "foreignDoc"
}
},
{
$lookup: {
from: "smallColl",
as: "smallCollDocs",
pipeline: [],
}
},
{$_internalSplitPipeline: {mergeType: "anyShard"}}
];
const results = coll.aggregate(pipeline).toArray();
assert.eq(results.length, nDocsMainColl);
for (let i = 0; i < results.length; i++) {
assert.eq(results[i].foreignDoc.length, 2, results[i]);
assert.eq(results[i].smallCollDocs.length, 1, results[i]);
}
})();
(function testUnshardedLookupWithinShardedLookup() {
// Pipeline with unsharded $lookup inside a sharded $lookup.
pipeline = [
{
$lookup: {
from: "foreignColl",
as: "foreignDoc",
pipeline: [
{$lookup: {from: "smallColl", as: "doc", pipeline: []}},
],
}
},
{$_internalSplitPipeline: {mergeType: "anyShard"}}
];
const results = coll.aggregate(pipeline).toArray();
assert.eq(results.length, nDocsMainColl);
for (let i = 0; i < results.length; i++) {
assert.eq(results[i].foreignDoc.length, nDocsForeignColl);
for (let j = 0; j < nDocsForeignColl; j++) {
// Each document pulled from the foreign collection should have one document
// from "smallColl."
assert.eq(results[i].foreignDoc[j].collName, "foreignColl");
// TODO SERVER-39016: Once a mongod is able to target the primary shard when
// reading from a non-sharded collection this should always work. Until then,
// the results of the query depend on which shard is chosen as the merging
// shard. If the primary shard is chosen, we'll get the correct results (and
// correctly find a document in "smallColl"). Otherwise if the merging shard is
// not the primary shard, the merging shard will attempt to do a local read (on
// an empty/non-existent collection), which will return nothing.
if (results[i].foreignDoc[j].doc.length === 1) {
assert.eq(results[i].foreignDoc[j].doc[0].collName, "smallColl");
} else {
assert.eq(results[i].foreignDoc[j].doc.length, 0);
}
}
}
})();
};
jsTestLog("Running test with neither collection sharded");
runTest();
jsTestLog("Running test with foreign collection sharded");
sharded.shardColl("foreignColl",
{_id: 1}, // shard key
{_id: 5}, // split
{_id: 5}, // move
"test", // dbName
true // waitForDelete
);
runTest();
jsTestLog("Running test with main and foreign collection sharded");
sharded.shardColl("mainColl",
{_id: 1}, // shard key
{_id: 5}, // split
{_id: 5}, // move
"test", // dbName
true // waitForDelete
);
runTest();
sharded.stop();
})();
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