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// Test that a pipeline of the form [{$changeStream: {}}, {$match: <predicate>}] with a predicate
// involving the 'documentKey' field can push down the $match and rewrite the $match and make it
// part of the oplog cursor's filter in order to filter out results as early as possible.
// @tags: [
// featureFlagChangeStreamsRewrite,
// requires_fcv_51,
// requires_pipeline_optimization,
// requires_sharding,
// uses_change_streams,
// change_stream_does_not_expect_txns,
// assumes_unsharded_collection,
// assumes_read_preference_unchanged
// ]
(function() {
"use strict";
load("jstests/libs/change_stream_rewrite_util.js"); // For rewrite helpers.
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.
const dbName = "change_stream_match_pushdown_documentKey_rewrite";
const collName = "change_stream_match_pushdown_documentKey_rewrite";
const st = new ShardingTest({
shards: 2,
rs: {nodes: 1, setParameter: {writePeriodicNoops: true, periodicNoopIntervalSecs: 1}}
});
const mongosConn = st.s;
const db = mongosConn.getDB(dbName);
// Returns a newly created sharded collection, where shard key is 'shard'.
const coll = createShardedCollection(st, "shard" /* shardKey */, dbName, collName, 1 /* splitAt */);
// A helper that opens a change stream with the user supplied match expression 'userMatchExpr' and
// validates that:
// (1) for each shard, the events are seen in that order as specified in 'expectedOps'; and
// (2) each shard returns the expected number of events; and
// (3) the number of docs returned by the oplog cursor on each shard matches what we expect
// as specified in 'expectedOplogCursorReturnedDocs'.
function verifyOps(resumeAfterToken, userMatchExpr, expectedOps, expectedOplogCursorReturnedDocs) {
const cursor =
coll.aggregate([{$changeStream: {resumeAfter: resumeAfterToken}}, userMatchExpr]);
let expectedChangeStreamDocsReturned = [0, 0];
for (const [op, id, shardId] of expectedOps) {
assert.soon(() => cursor.hasNext());
const event = cursor.next();
assert.eq(event.operationType, op, event);
assert.eq(event.documentKey._id, id, event);
assert.eq(event.documentKey.shard, shardId, event);
if (shardId == 0 || shardId == 1) {
++expectedChangeStreamDocsReturned[shardId];
}
}
assert(!cursor.hasNext());
// An 'executionStats' could only be captured for a non-invalidating stream.
const stats = coll.explain("executionStats")
.aggregate([{$changeStream: {resumeAfter: resumeAfterToken}}, userMatchExpr]);
assertNumChangeStreamDocsReturnedFromShard(
stats, st.rs0.name, expectedChangeStreamDocsReturned[0]);
assertNumChangeStreamDocsReturnedFromShard(
stats, st.rs1.name, expectedChangeStreamDocsReturned[1]);
assertNumMatchingOplogEventsForShard(stats, st.rs0.name, expectedOplogCursorReturnedDocs[0]);
assertNumMatchingOplogEventsForShard(stats, st.rs1.name, expectedOplogCursorReturnedDocs[1]);
}
// Open a change stream and store the resume token. This resume token will be used to replay the
// stream after this point.
const resumeAfterToken = coll.watch([]).getResumeToken();
// These operations will create oplog events. The change stream will apply several filters on these
// series of events and ensure that the '$match' expressions are rewritten correctly.
assert.commandWorked(coll.insert({_id: 2, shard: 0}));
assert.commandWorked(coll.insert({_id: 3, shard: 0, z: 4}));
assert.commandWorked(coll.insert({_id: 2, shard: 1, z: 4}));
assert.commandWorked(coll.insert({_id: 3, shard: 1}));
assert.commandWorked(coll.update({_id: 2, shard: 0}, {$set: {foo: "a"}}));
assert.commandWorked(coll.update({_id: 3, shard: 0}, {$set: {foo: "a"}}));
assert.commandWorked(coll.update({_id: 2, shard: 1}, {$set: {foo: "a"}}));
assert.commandWorked(coll.update({_id: 3, shard: 1}, {$set: {foo: "a"}}));
assert.commandWorked(coll.replaceOne({_id: 2, shard: 0}, {_id: 2, shard: 0, foo: "b"}));
assert.commandWorked(coll.replaceOne({_id: 3, shard: 0}, {_id: 3, shard: 0, z: 4, foo: "b"}));
assert.commandWorked(coll.replaceOne({_id: 2, shard: 1}, {_id: 2, shard: 1, z: 4, foo: "b"}));
assert.commandWorked(coll.replaceOne({_id: 3, shard: 1}, {_id: 3, shard: 1, foo: "b"}));
assert.commandWorked(coll.deleteOne({_id: 2, shard: 0}));
assert.commandWorked(coll.deleteOne({_id: 3, shard: 0}));
assert.commandWorked(coll.deleteOne({_id: 2, shard: 1}));
assert.commandWorked(coll.deleteOne({_id: 3, shard: 1}));
// Enable a failpoint that will prevent $expr match expressions from generating $_internalExprEq
// or similar expressions. This ensures that the following test-cases only exercise the $expr
// rewrites.
assert.commandWorked(
db.adminCommand({configureFailPoint: "disableMatchExpressionOptimization", mode: "alwaysOn"}));
FixtureHelpers.runCommandOnEachPrimary({
db: db.getSiblingDB("admin"),
cmdObj: {configureFailPoint: "disableMatchExpressionOptimization", mode: "alwaysOn"}
});
// Ensure that the '$match' on the 'insert', 'update', 'replace', and 'delete' operation types with
// various predicates are rewritten correctly.
for (const op of ["insert", "update", "replace", "delete"]) {
// Test out a predicate on the full 'documentKey' field.
verifyOps(resumeAfterToken,
{$match: {operationType: op, documentKey: {shard: 0, _id: 2}}},
[[op, 2, 0]],
[1, 0] /* expectedOplogCursorReturnedDocs */);
// Test out a predicate on 'documentKey._id'.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey._id": 2}},
[[op, 2, 0], [op, 2, 1]],
[1, 1] /* expectedOplogCursorReturnedDocs */);
// Test out a predicate on 'documentKey.shard'.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey.shard": 1}},
[[op, 2, 1], [op, 3, 1]],
[0, 2] /* expectedOplogCursorReturnedDocs */);
// Test out a negated predicate on the full 'documentKey' field. It's not possible to rewrite
// this predicate and make it part of the oplog filter, so we expect the oplog cursor to return
// 2 docs on each shard.
verifyOps(resumeAfterToken,
{$match: {operationType: op, documentKey: {$not: {$eq: {shard: 0, _id: 2}}}}},
[[op, 3, 0], [op, 2, 1], [op, 3, 1]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out a negated predicate on 'documentKey._id'.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey._id": {$not: {$eq: 2}}}},
[[op, 3, 0], [op, 3, 1]],
[1, 1] /* expectedOplogCursorReturnedDocs */);
// Test out an {$eq: null} predicate on 'documentKey._id'.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey._id": {$eq: null}}},
[],
[0, 0] /* expectedOplogCursorReturnedDocs */);
// Test out a negated predicate on 'documentKey.shard'. It's not possible to rewrite this
// predicate and make it part of the oplog filter, so we expect the oplog cursor to return 2
// docs on each shard.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey.shard": {$not: {$eq: 1}}}},
[[op, 2, 0], [op, 3, 0]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out the '{$exists: false}' predicate on a field that doesn't exist in 'documentKey' but
// that does exist in some of the underlying documents.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey.z": {$exists: false}}},
[[op, 2, 0], [op, 3, 0], [op, 2, 1], [op, 3, 1]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out the '{$eq: null}' predicate on a field that doesn't exist in 'documentKey' but that
// does exist in some of the underlying documents.
verifyOps(resumeAfterToken,
{$match: {operationType: op, "documentKey.z": {$eq: null}}},
[[op, 2, 0], [op, 3, 0], [op, 2, 1], [op, 3, 1]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out an $expr predicate on the full 'documentKey' field.
verifyOps(
resumeAfterToken,
{
$match:
{$and: [{operationType: op}, {$expr: {$eq: ["$documentKey", {shard: 0, _id: 2}]}}]}
},
[[op, 2, 0]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out a negated predicate on the full 'documentKey' field.
verifyOps(resumeAfterToken,
{
$match: {
$and: [
{operationType: op},
{$expr: {$not: {$eq: ["$documentKey", {shard: 0, _id: 2}]}}}
]
}
},
[[op, 3, 0], [op, 2, 1], [op, 3, 1]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out an $expr predicate on 'documentKey._id'.
verifyOps(resumeAfterToken,
{$match: {$and: [{operationType: op}, {$expr: {$eq: ["$documentKey._id", 2]}}]}},
[[op, 2, 0], [op, 2, 1]],
[1, 1] /* expectedOplogCursorReturnedDocs */);
// Test out a negated $expr predicate on 'documentKey._id'.
verifyOps(
resumeAfterToken,
{$match: {$and: [{operationType: op}, {$expr: {$not: {$eq: ["$documentKey._id", 2]}}}]}},
[[op, 3, 0], [op, 3, 1]],
[1, 1] /* expectedOplogCursorReturnedDocs */);
// Test out an $expr predicate on 'documentKey.shard'.
verifyOps(resumeAfterToken,
{$match: {$and: [{operationType: op}, {$expr: {$eq: ["$documentKey.shard", 1]}}]}},
[[op, 2, 1], [op, 3, 1]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
// Test out a negated $expr predicate on 'documentKey.shard'.
verifyOps(
resumeAfterToken,
{$match: {$and: [{operationType: op}, {$expr: {$not: {$eq: ["$documentKey.shard", 1]}}}]}},
[[op, 2, 0], [op, 3, 0]],
[2, 2] /* expectedOplogCursorReturnedDocs */);
}
st.stop();
})();
|
