108 lines
3.8 KiB
JavaScript
108 lines
3.8 KiB
JavaScript
// Test subtleties of batchSize and limit.
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var t = db.jstests_batch_size;
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t.drop();
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for (var i = 0; i < 4; i++) {
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t.save({_id: i, a: i});
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}
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function runIndexedTests() {
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// With limit, indexed.
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assert.eq(2, t.find().limit(2).itcount(), 'G');
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assert.eq(2, t.find().sort({a: 1}).limit(2).itcount(), 'H');
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// With batchSize, indexed.
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// SERVER-12438: If there is an index that provides the sort,
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// then a plan with an unindexed sort should never be used.
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// Consequently, batchSize will NOT be a hard limit in this case.
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// WARNING: the behavior described above may change in the future.
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assert.eq(4, t.find().batchSize(2).itcount(), 'I');
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assert.eq(4, t.find().sort({a: 1}).batchSize(2).itcount(), 'J');
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}
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// Without batch size or limit, unindexed.
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assert.eq(4, t.find().itcount(), 'A');
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assert.eq(4, t.find().sort({a: 1}).itcount(), 'B');
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// With limit, unindexed.
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assert.eq(2, t.find().limit(2).itcount(), 'C');
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assert.eq(2, t.find().sort({a: 1}).limit(2).itcount(), 'D');
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assert.eq(4, t.find().batchSize(2).itcount(), 'E');
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assert.eq(4, t.find().sort({a: 1}).batchSize(2).itcount(), 'F');
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// Run the tests with the index twice in order to double check plan caching.
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t.ensureIndex({a: 1});
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for (var i = 0; i < 2; i++) {
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runIndexedTests();
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}
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// The next tests make sure that we obey limit and batchSize properly when
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// the sort could be either indexed or unindexed.
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t.drop();
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t.ensureIndex({a: 1});
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t.ensureIndex({b: 1});
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for (var i = 0; i < 100; i++) {
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t.save({_id: i, a: i, b: 1});
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}
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// Without a hint. Do it twice to make sure caching is ok.
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for (var i = 0; i < 2; i++) {
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assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).batchSize(2).itcount(), 'K');
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assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).limit(6).itcount(), 'L');
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}
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// Hinting 'a'.
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assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).hint({a: 1}).batchSize(2).itcount(), 'M');
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assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).hint({a: 1}).limit(6).itcount(), 'N');
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// Hinting 'b'.
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assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).hint({b: 1}).batchSize(2).itcount(), 'O');
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assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).hint({b: 1}).limit(6).itcount(), 'P');
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// With explain.
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var explain = t.find({a: {$gte: 85}}).sort({b: 1}).batchSize(2).explain("executionStats");
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assert.eq(15, explain.executionStats.nReturned, 'Q');
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explain = t.find({a: {$gte: 85}}).sort({b: 1}).limit(6).explain("executionStats");
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assert.eq(6, explain.executionStats.nReturned, 'R');
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// Double check that we're not scanning more stuff than we have to.
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// In order to get the sort using index 'a', we should need to scan
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// about 50 keys and 50 documents.
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var explain = t.find({a: {$gte: 50}}).sort({b: 1}).hint({a: 1}).limit(6).explain("executionStats");
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assert.lte(explain.executionStats.totalKeysExamined, 60, 'S');
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assert.lte(explain.executionStats.totalDocsExamined, 60, 'T');
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assert.eq(explain.executionStats.nReturned, 6, 'U');
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// -------
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// During plan ranking, we treat ntoreturn as a limit. This prevents us from buffering
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// too much data in a blocking sort stage during plan ranking.
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t.drop();
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// Generate big string to use in the object - 1MB+ String
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var bigStr = "ABCDEFGHIJKLMNBOPQRSTUVWXYZ012345687890";
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while (bigStr.length < 1000000) { bigStr = bigStr + "::" + bigStr; }
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// Insert enough documents to exceed the 32 MB in-memory sort limit.
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for (var i = 0; i < 40; i++) {
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var doc = {x: 1, y: 1, z: i, big: bigStr};
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t.insert(doc);
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}
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// Two indices needed in order to trigger plan ranking. Neither index provides
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// the sort order.
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t.ensureIndex({x: 1});
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t.ensureIndex({y: 1});
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// We should only buffer 3 docs in memory.
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var cursor = t.find({x: 1, y: 1}).sort({z: -1}).limit(3);
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assert.eq(39, cursor.next()["z"]);
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assert.eq(38, cursor.next()["z"]);
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assert.eq(37, cursor.next()["z"]);
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assert(!cursor.hasNext());
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