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/**
* Confirms that the query plan cache is cleared on index build completion, making the newly created
* index available to queries that had a cached plan prior to the build.
* @tags: [requires_replication]
*/
(function() {
"use strict";
const dbName = "test";
const collName = "coll";
// Returns whether there is an active index build.
function indexBuildIsRunning(testDB, indexName) {
const indexBuildFilter = {
"command.createIndexes": collName,
"command.indexes.0.name": indexName,
"msg": /^Index Build/
};
const curOp =
testDB.getSiblingDB("admin").aggregate([{$currentOp: {}}, {$match: indexBuildFilter}]);
return curOp.hasNext();
}
// Returns whether a cached plan exists for 'query'.
function assertDoesNotHaveCachedPlan(coll, query) {
const match = {"createdFromQuery.query": query};
assert.eq([], coll.getPlanCache().list([{$match: match}]), coll.getPlanCache().list());
}
// Returns the cached plan for 'query'.
function getIndexNameForCachedPlan(coll, query) {
const match = {"createdFromQuery.query": query};
const plans = coll.getPlanCache().list([{$match: match}]);
assert.eq(plans.length, 1, coll.getPlanCache().list());
assert(plans[0].hasOwnProperty("cachedPlan"), plans);
assert(plans[0].cachedPlan.hasOwnProperty("inputStage"), plans);
assert(plans[0].cachedPlan.inputStage.hasOwnProperty("indexName"), plans);
return plans[0].cachedPlan.inputStage.indexName;
}
function runTest({rst, readDB, writeDB}) {
const readColl = readDB.getCollection(collName);
const writeColl = writeDB.getCollection(collName);
assert.commandWorked(writeDB.runCommand({dropDatabase: 1, writeConcern: {w: "majority"}}));
const bulk = writeColl.initializeUnorderedBulkOp();
for (let i = 0; i < 100; ++i) {
bulk.insert({x: i, y: i % 10, z: 0});
}
assert.commandWorked(bulk.execute({w: "majority"}));
// We start with a baseline of 2 existing indexes as we will not cache plans when only a
// single plan exists.
assert.commandWorked(writeDB.runCommand({
createIndexes: collName,
indexes: [
{key: {y: 1}, name: "less_selective", background: false},
{key: {z: 1}, name: "least_selective", background: false}
],
writeConcern: {w: "majority"}
}));
rst.awaitReplication();
//
// Confirm that the plan cache is reset on start and completion of a background index build.
//
// Execute a find and confirm that a cached plan exists for an existing index.
const filter = {x: 50, y: 0, z: 0};
assert.eq(readColl.find(filter).itcount(), 1);
assert.eq("less_selective", getIndexNameForCachedPlan(readColl, filter));
// Enable a failpoint that will cause an index build to block just after start. This will
// allow us to examine PlanCache contents while index creation is in flight.
assert.commandWorked(
readDB.adminCommand({configureFailPoint: 'hangAfterStartingIndexBuild', mode: 'alwaysOn'}));
// The commitIndexBuild oplog entry may block $planCacheStats on the secondary during oplog
// application because it will hold the PBWM while waiting for the index build to complete in
// the backgroud. Therefore, we get the primary to hold off on writing the commitIndexBuild
// oplog entry until we are ready to resume index builds on the secondary.
if (writeDB.getMongo().host != readDB.getMongo().host) {
assert.commandWorked(writeDB.adminCommand(
{configureFailPoint: 'hangAfterStartingIndexBuild', mode: 'alwaysOn'}));
}
// Build a "most selective" index in the background.
TestData.dbName = dbName;
TestData.collName = collName;
const createIdxShell = startParallelShell(function() {
const testDB = db.getSiblingDB(TestData.dbName);
assert.commandWorked(testDB.runCommand({
createIndexes: TestData.collName,
indexes: [{key: {x: 1}, name: "most_selective", background: true}],
writeConcern: {w: "majority"}
}));
}, writeDB.getMongo().port);
// Confirm that the index build has started.
assert.soon(() => indexBuildIsRunning(readDB, "most_selective"),
"Index build operation not found after starting via parallelShell");
// Confirm that there are no cached plans post index build start.
assertDoesNotHaveCachedPlan(readColl, filter);
// Execute a find and confirm that a previously built index is the cached plan.
assert.eq(readColl.find(filter).itcount(), 1);
assert.eq("less_selective", getIndexNameForCachedPlan(readColl, filter));
// Disable the hang and wait for the index build to complete.
assert.commandWorked(
readDB.adminCommand({configureFailPoint: 'hangAfterStartingIndexBuild', mode: 'off'}));
// No effect if the fail point is already disabled.
assert.commandWorked(
writeDB.adminCommand({configureFailPoint: 'hangAfterStartingIndexBuild', mode: 'off'}));
assert.soon(() => !indexBuildIsRunning(readDB, "most_selective"));
createIdxShell({checkExitSuccess: true});
rst.awaitReplication();
// Confirm that there are no cached plans post index build.
assertDoesNotHaveCachedPlan(readColl, filter);
// Now that the index has been built, execute another find and confirm that the newly
// created index is used.
assert.eq(readColl.find(filter).itcount(), 1);
assert.eq("most_selective", getIndexNameForCachedPlan(readColl, filter));
// Drop the newly created index and confirm that the plan cache has been cleared.
assert.commandWorked(
writeDB.runCommand({dropIndexes: collName, index: {x: 1}, writeConcern: {w: "majority"}}));
assertDoesNotHaveCachedPlan(readColl, filter);
//
// Confirm that the plan cache is reset post foreground index build.
//
// Execute a find and confirm that an existing index is in the cache.
assert.eq(readColl.find(filter).itcount(), 1);
assert.eq("less_selective", getIndexNameForCachedPlan(readColl, filter));
// Build a "most selective" index in the foreground.
assert.commandWorked(writeDB.runCommand({
createIndexes: collName,
indexes: [{key: {x: 1}, name: "most_selective", background: false}],
writeConcern: {w: "majority"}
}));
rst.awaitReplication();
// Confirm that there are no cached plans post index build.
assertDoesNotHaveCachedPlan(readColl, filter);
// Execute a find and confirm that the newly created index is used.
assert.eq(readColl.find(filter).itcount(), 1);
assert.eq("most_selective", getIndexNameForCachedPlan(readColl, filter));
// Drop the newly created index and confirm that the plan cache has been cleared.
assert.commandWorked(
writeDB.runCommand({dropIndexes: collName, index: {x: 1}, writeConcern: {w: "majority"}}));
assertDoesNotHaveCachedPlan(readColl, filter);
}
const rst = new ReplSetTest({nodes: 2});
rst.startSet();
rst.initiate();
const primaryDB = rst.getPrimary().getDB(dbName);
const secondaryDB = rst.getSecondary().getDB(dbName);
runTest({rst: rst, readDB: primaryDB, writeDB: primaryDB});
runTest({rst: rst, readDB: secondaryDB, writeDB: primaryDB});
rst.stopSet();
})();
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