> db.foo.drop()
> db.foo2.drop()
> db.foo.createIndex({a:1})
> db.foo.insert({a:1})
> db.foo2.insert({b:1})
> db.adminCommand({setParameter: 1, notablescan: 1})

// In SBE, the following succeeds (uses a hash join)
> db.foo.aggregate([{$match: {a: 1}}, {$lookup: {from: "foo2", as: "res", localField: "a", foreignField: "b"}}]) 

// In classic, it fails
> db.adminCommand({setParameter: 1, internalQueryFrameworkControl: 'forceClassicEngine'})
> db.foo.aggregate([{$match: {a: 1}}, {$lookup: {from: "foo2", as: "res", localField: "a", foreignField: "b"}}])

"Executor error during aggregate command on namespace: test.foo :: caused by :: No indexed plans available, and running with 'notablescan' 2",