109 lines
2.7 KiB
JavaScript
109 lines
2.7 KiB
JavaScript
// Check $first/$last group accumulators. SERVER-3862
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// $first/$last select first/last value for a group key from the previous pipeline.
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t = db.jstests_aggregation_firstlast;
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t.drop();
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/** Check expected $first and $last result values. */
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function assertFirstLast(expectedFirst, expectedLast, pipeline, expression) {
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pipeline = pipeline || [];
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expression = expression || '$b';
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pipeline.push({$group: {_id: '$a', first: {$first: expression}, last: {$last: expression}}});
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result = t.aggregate(pipeline).toArray();
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for (var i = 0; i < result.length; ++i) {
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if (result[i]._id == 1) {
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// Check results for group _id 1.
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assert.eq(expectedFirst, result[i].first);
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assert.eq(expectedLast, result[i].last);
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return;
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}
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}
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assert(false, "Expected group _id '1' missing.");
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}
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// One document.
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t.save({a: 1, b: 1});
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assertFirstLast(1, 1);
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// Two documents.
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t.save({a: 1, b: 2});
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assertFirstLast(1, 2);
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// Three documents.
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t.save({a: 1, b: 3});
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assertFirstLast(1, 3);
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// Another 'a' key value does not affect outcome.
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t.drop();
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t.save({a: 3, b: 0});
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t.save({a: 1, b: 1});
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t.save({a: 1, b: 2});
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t.save({a: 1, b: 3});
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t.save({a: 2, b: 0});
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assertFirstLast(1, 3);
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// Additional pipeline stages do not affect outcome if order is maintained.
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assertFirstLast(1, 3, [{$project: {x: '$a', y: '$b'}}, {$project: {a: '$x', b: '$y'}}]);
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// Additional pipeline stages affect outcome if order is modified.
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assertFirstLast(3, 1, [{$sort: {b: -1}}]);
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// Skip and limit affect the results seen.
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t.drop();
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t.save({a: 1, b: 1});
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t.save({a: 1, b: 2});
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t.save({a: 1, b: 3});
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assertFirstLast(1, 2, [{$limit: 2}]);
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assertFirstLast(2, 3, [{$skip: 1}, {$limit: 2}]);
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assertFirstLast(2, 2, [{$skip: 1}, {$limit: 1}]);
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// Mixed type values.
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t.save({a: 1, b: 'foo'});
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assertFirstLast(1, 'foo');
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t.drop();
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t.save({a: 1, b: 'bar'});
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t.save({a: 1, b: true});
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assertFirstLast('bar', true);
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// Value null.
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t.drop();
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t.save({a: 1, b: null});
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t.save({a: 1, b: 2});
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assertFirstLast(null, 2);
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t.drop();
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t.save({a: 1, b: 2});
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t.save({a: 1, b: null});
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assertFirstLast(2, null);
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t.drop();
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t.save({a: 1, b: null});
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t.save({a: 1, b: null});
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assertFirstLast(null, null);
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// Value missing.
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t.drop();
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t.save({a: 1});
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t.save({a: 1, b: 2});
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assertFirstLast(undefined, 2);
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t.drop();
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t.save({a: 1, b: 2});
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t.save({a: 1});
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assertFirstLast(2, undefined);
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t.drop();
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t.save({a: 1});
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t.save({a: 1});
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assertFirstLast(undefined, undefined);
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// Dotted field.
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t.drop();
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t.save({a: 1, b: [{c: 1}, {c: 2}]});
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t.save({a: 1, b: [{c: 6}, {}]});
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assertFirstLast([1, 2], [6], [], '$b.c');
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// Computed expressions.
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t.drop();
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t.save({a: 1, b: 1});
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t.save({a: 1, b: 2});
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assertFirstLast(1, 0, [], {$mod: ['$b', 2]});
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assertFirstLast(0, 1, [], {$mod: [{$add: ['$b', 1]}, 2]});
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