/
lookup_pushdown.js
252 lines (215 loc) · 9.38 KB
/
lookup_pushdown.js
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/**
* Tests basic functionality of pushing $lookup into the find layer.
*/
(function() {
"use strict";
load("jstests/libs/sbe_util.js"); // For checkSBEEnabled.
const JoinAlgorithm = {
HJ: 5842602,
INLJ: 5842603,
NLJ: 5842604,
};
function runTest(coll, pipeline, expectedCode, aggOptions = {}) {
const cmd = () => coll.aggregate(pipeline, aggOptions).toArray();
if (expectedCode) {
assert.throwsWithCode(cmd, expectedCode);
} else {
assert.doesNotThrow(cmd);
}
}
// Standalone cases.
const conn = MongoRunner.runMongod({setParameter: "internalEnableMultipleAutoGetCollections=true"});
assert.neq(null, conn, "mongod was unable to start up");
const name = "lookup_pushdown";
let db = conn.getDB(name);
if (!checkSBEEnabled(db, ["featureFlagSBELookupPushdown"])) {
jsTestLog("Skipping test because the sbe lookup pushdown feature flag is disabled");
MongoRunner.stopMongod(conn);
return;
}
const foreignCollName = "foreign_lookup_pushdown";
const viewName = "view_lookup_pushdown";
let coll = db[name];
assert.commandWorked(coll.insert({_id: 1, a: 2}));
let foreignColl = db[foreignCollName];
assert.commandWorked(foreignColl.insert({_id: 0, b: 2, c: 2}));
assert.commandWorked(db.createView(viewName, foreignCollName, [{$match: {b: {$gte: 0}}}]));
let view = db[viewName];
// Basic $lookup.
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.NLJ /* expectedCode */);
// Self join $lookup, no views.
runTest(coll,
[{$lookup: {from: name, localField: "a", foreignField: "a", as: "out"}}],
JoinAlgorithm.NLJ /* expectedCode */);
// Self join $lookup; left hand is a view. This is expected to be pushed down because the view
// pipeline itself is a $match, which is eligible for pushdown.
runTest(view,
[{$lookup: {from: name, localField: "a", foreignField: "a", as: "out"}}],
JoinAlgorithm.NLJ /* expectedCode */);
// Self join $lookup; right hand is a view.
runTest(coll,
[{$lookup: {from: viewName, localField: "a", foreignField: "a", as: "out"}}],
false /* expectedCode */);
// Self join $lookup; both namespaces are views.
runTest(view,
[{$lookup: {from: viewName, localField: "a", foreignField: "a", as: "out"}}],
false /* expectedCode */);
// $lookup preceded by $match.
runTest(coll,
[
{$match: {a: {$gte: 0}}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}
],
JoinAlgorithm.NLJ /* expectedCode */);
// $lookup preceded by $project.
runTest(coll,
[
{$project: {a: 1}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}
],
JoinAlgorithm.NLJ /* expectedCode */);
// $lookup preceded by $project which features an SBE-incompatible expression.
// TODO SERVER-51542: Update or remove this test case once $pow is implemented in SBE.
runTest(coll,
[
{$project: {exp: {$pow: ["$a", 3]}}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}
],
false /* expectedCode */);
// $lookup preceded by $group.
runTest(coll,
[
{$group: {_id: "$a", sum: {$sum: 1}}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}
],
JoinAlgorithm.NLJ /* expectedCode */);
// Consecutive $lookups (first is against view).
runTest(coll,
[
{$lookup: {from: viewName, localField: "a", foreignField: "b", as: "out"}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}
],
false /* expectedCode */);
// Consecutive $lookups (first is against regular collection).
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}},
{$lookup: {from: viewName, localField: "a", foreignField: "b", as: "out"}}
],
JoinAlgorithm.NLJ /* expectedCode */);
// $lookup with pipeline.
runTest(coll,
[{$lookup: {from: foreignCollName, let: {foo: "$b"}, pipeline: [{$match: {$expr: {$eq: ["$$foo",
2]}}}], as: "out"}}], false /* expectedCode */);
// $lookup that absorbs $unwind.
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}},
{$unwind: "$out"}
],
false /* expectedCode */);
// $lookup that absorbs $match.
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}},
{$unwind: "$out"},
{$match: {out: {$gte: 0}}}
],
false /* expectedCode */);
// $lookup that does not absorb $match.
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}},
{$match: {out: {$gte: 0}}}
],
JoinAlgorithm.NLJ /* expectedCode */);
// Run a $lookup with 'allowDiskUse' enabled. Because the foreign collection is very small, we
// should select hash join.
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.HJ /* expectedCode */,
{allowDiskUse: true});
// Build an index on the foreign collection that matches the foreignField. This should cause us
// to choose an indexed nested loop join.
assert.commandWorked(foreignColl.createIndex({b: 1}));
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.INLJ /* expectedCode */);
// Build a compound index that is prefixed with the foreignField. We should use an indexed
// nested loop join.
assert.commandWorked(foreignColl.dropIndexes());
assert.commandWorked(foreignColl.createIndex({b: 1, c: 1, a: 1}));
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.INLJ /* expectedCode */);
// Build a compound index containing the foreignField, but not as the first field. In this case,
// we should use regular nested loop join.
assert.commandWorked(foreignColl.dropIndexes());
assert.commandWorked(foreignColl.createIndex({a: 1, b: 1, c: 1}));
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.NLJ /* expectedCode */);
// Multiple $lookup stages in a pipeline that should pick different physical joins.
assert.commandWorked(foreignColl.dropIndexes());
assert.commandWorked(foreignColl.createIndex({b: 1}));
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "b_out"}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "c", as: "c_out"}}
],
JoinAlgorithm.NLJ /* expectedCode for the second stage, because it's built first */);
runTest(coll,
[
{$lookup: {from: foreignCollName, localField: "a", foreignField: "c", as: "c_out"}},
{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "b_out"}}
],
JoinAlgorithm.INLJ /* expectedCode for the second stage, because it's built first */);
MongoRunner.stopMongod(conn);
// Sharded cases.
const st = new ShardingTest({
shards: 2,
mongos: 1,
other: {shardOptions: {setParameter: "internalEnableMultipleAutoGetCollections=true"}}
});
db = st.s.getDB(name);
// Setup. Here, 'coll' is sharded, 'foreignColl' is unsharded, 'viewName' is an unsharded view,
// and 'shardedViewName' is a sharded view.
const shardedViewName = "sharded_foreign_view";
coll = db[name];
assert.commandWorked(coll.insert({a: 1, shardKey: 1}));
assert.commandWorked(coll.insert({a: 2, shardKey: 10}));
assert.commandWorked(coll.createIndex({shardKey: 1}));
st.shardColl(coll.getName(), {shardKey: 1}, {shardKey: 5}, {shardKey: 5}, name);
foreignColl = db[foreignCollName];
assert.commandWorked(foreignColl.insert({b: 5}));
assert.commandWorked(db.createView(viewName, foreignCollName, [{$match: {b: {$gte: 0}}}]));
assert.commandWorked(db.createView(shardedViewName, name, [{$match: {b: {$gte: 0}}}]));
// Both collections are unsharded.
runTest(foreignColl,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
JoinAlgorithm.NLJ /* expectedCode */);
// Sharded main collection, unsharded right side. This is not expected to be eligible for pushdown
// because the $lookup will be preceded by a $mergeCursors stage on the merging shard.
runTest(coll,
[{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
false /* expectedCode */);
// Both collections are sharded.
runTest(coll,
[{$lookup: {from: name, localField: "a", foreignField: "b", as: "out"}}],
false /* expectedCode */);
// Unsharded main collection, sharded right side.
runTest(foreignColl,
[{$lookup: {from: name, localField: "a", foreignField: "b", as: "out"}}],
false /* expectedCode */);
// Unsharded main collection, unsharded view right side.
runTest(foreignColl,
[{$lookup: {from: viewName, localField: "a", foreignField: "b", as: "out"}}],
false /* expectedCode */);
// Unsharded main collection, sharded view on the right side.
runTest(foreignColl,
[{$lookup: {from: shardedViewName, localField: "a", foreignField: "b", as: "out"}}],
false /* expectedCode */);
st.stop();
}());