mirror of https://github.com/mongodb/mongo
50 lines
1.6 KiB
JavaScript
50 lines
1.6 KiB
JavaScript
/**
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* Verify that $sample push down works properly in a transaction. This test was designed to
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* reproduce SERVER-57642.
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*
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* Requires random cursor support.
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* @tags: [requires_replication]
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*/
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import {aggPlanHasStage} from "jstests/libs/query/analyze_plan.js";
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import {ReplSetTest} from "jstests/libs/replsettest.js";
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// Set up.
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const rst = new ReplSetTest({nodes: 1});
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rst.startSet();
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rst.initiate();
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const collName = "sample_pushdown";
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const dbName = "test";
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const testDB = rst.getPrimary().getDB(dbName);
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const coll = testDB[collName];
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// In order to construct a plan that uses a storage engine random cursor, we not only need more
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// than 100 records in our collection, we also need the sample size to be less than 5% of the
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// number of documents in our collection.
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const numDocs = 1000;
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const sampleSize = numDocs * 0.03;
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let docs = [];
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for (let i = 0; i < numDocs; ++i) {
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docs.push({a: i});
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}
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assert.commandWorked(coll.insert(docs));
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const pipeline = [{$sample: {size: sampleSize}}, {$match: {a: {$gte: 0}}}];
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// Verify that our pipeline uses $sample push down.
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const explain = coll.explain().aggregate(pipeline);
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assert(aggPlanHasStage(explain, "$sampleFromRandomCursor"), tojson(explain));
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// Start the transaction.
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const session = testDB.getMongo().startSession({causalConsistency: false});
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const sessionDB = session.getDatabase(dbName);
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session.startTransaction();
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// Run the pipeline.
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const randDocs = sessionDB[collName].aggregate(pipeline).toArray();
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// Verify that we have at least one result.
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assert.gt(randDocs.length, 0, tojson(randDocs));
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// Clean up.
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assert.commandWorked(session.abortTransaction_forTesting());
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rst.stopSet();
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