122 lines
4.9 KiB
JavaScript
122 lines
4.9 KiB
JavaScript
// Test running explains on count commands.
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var collName = "jstests_explain_count";
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var t = db[collName];
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t.drop();
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/**
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* Given explain output 'explain' at executionStats level verbosity,
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* confirms that the root stage is COUNT and that the result of the
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* count is equal to 'nCounted'.
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*/
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function checkCountExplain(explain, nCounted) {
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printjson(explain);
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var execStages = explain.executionStats.executionStages;
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// If passed through mongos, then the root stage should be the mongos SINGLE_SHARD stage,
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// with COUNT as its child. If explaining directly on the shard, then COUNT is the root
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// stage.
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if ("SINGLE_SHARD" == execStages.stage) {
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var countStage = execStages.shards[0].executionStages;
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assert.eq(countStage.stage, "COUNT", "root stage on shard is not COUNT");
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assert.eq(countStage.nCounted, nCounted, "wrong count result");
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}
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else {
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assert.eq(execStages.stage, "COUNT", "root stage is not COUNT");
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assert.eq(execStages.nCounted, nCounted, "wrong count result");
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}
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}
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// Collection does not exist.
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assert.eq(0, t.count());
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var explain = db.runCommand({explain: {count: collName}, verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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// Collection does not exist with skip, limit, and/or query.
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assert.eq(0, db.runCommand({count: collName, skip: 3}).n);
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explain = db.runCommand({explain: {count: collName, skip: 3}, verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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assert.eq(0, db.runCommand({count: collName, limit: 3}).n);
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explain = db.runCommand({explain: {count: collName, limit: 3}, verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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assert.eq(0, db.runCommand({count: collName, limit: -3}).n);
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explain = db.runCommand({explain: {count: collName, limit: -3}, verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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assert.eq(0, db.runCommand({count: collName, limit: -3, skip: 4}).n);
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explain = db.runCommand({explain: {count: collName, limit: -3, skip: 4},
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verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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assert.eq(0, db.runCommand({count: collName, query: {a: 1}, limit: -3, skip: 4}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 1}, limit: -3, skip: 4},
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verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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// Now add a bit of data to the collection.
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t.ensureIndex({a: 1});
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for (var i = 0; i < 10; i++) {
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t.insert({_id: i, a: 1});
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}
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// Trivial count with no skip, limit, or query.
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assert.eq(10, t.count());
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explain = db.runCommand({explain: {count: collName}, verbosity: "executionStats"});
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checkCountExplain(explain, 10);
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// Trivial count with skip.
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assert.eq(7, db.runCommand({count: collName, skip: 3}).n);
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explain = db.runCommand({explain: {count: collName, skip: 3}, verbosity: "executionStats"});
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checkCountExplain(explain, 7);
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// Trivial count with limit.
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assert.eq(3, db.runCommand({count: collName, limit: 3}).n);
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explain = db.runCommand({explain: {count: collName, limit: 3}, verbosity: "executionStats"});
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checkCountExplain(explain, 3);
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// Trivial count with negative limit.
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assert.eq(3, db.runCommand({count: collName, limit: -3}).n);
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explain = db.runCommand({explain: {count: collName, limit: -3}, verbosity: "executionStats"});
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checkCountExplain(explain, 3);
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// Trivial count with both limit and skip.
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assert.eq(3, db.runCommand({count: collName, limit: -3, skip: 4}).n);
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explain = db.runCommand({explain: {count: collName, limit: -3, skip: 4},
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verbosity: "executionStats"});
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checkCountExplain(explain, 3);
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// With a query.
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assert.eq(10, db.runCommand({count: collName, query: {a: 1}}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 1}},
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verbosity: "executionStats"});
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checkCountExplain(explain, 10);
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// With a query and skip.
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assert.eq(7, db.runCommand({count: collName, query: {a: 1}, skip: 3}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 1}, skip: 3},
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verbosity: "executionStats"});
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checkCountExplain(explain, 7);
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// With a query and limit.
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assert.eq(3, db.runCommand({count: collName, query: {a: 1}, limit: 3}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 1}, limit: 3},
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verbosity: "executionStats"});
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checkCountExplain(explain, 3);
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// Insert one more doc for the last few tests.
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t.insert({a: 2});
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// Case where all results are skipped.
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assert.eq(0, db.runCommand({count: collName, query: {a: 2}, skip: 2}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 2}, skip: 2},
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verbosity: "executionStats"});
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checkCountExplain(explain, 0);
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// Case where we have a limit, but we don't hit it.
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assert.eq(1, db.runCommand({count: collName, query: {a: 2}, limit: 2}).n);
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explain = db.runCommand({explain: {count: collName, query: {a: 2}, limit: 2},
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verbosity: "executionStats"});
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checkCountExplain(explain, 1);
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