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diff --git a/jstests/core/explainb.js b/jstests/core/explainb.js
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+// nscanned and nscannedObjects report results for the winning plan; nscannedAllPlans and
+// nscannedObjectsAllPlans report results for all plans.  SERVER-6268
+//
+// This file tests the output of .explain.
+
+t = db.jstests_explainb;
+t.drop();
+
+t.ensureIndex( { a:1, b:1 } );
+t.ensureIndex( { b:1, a:1 } );
+
+t.save( { a:0, b:1 } );
+t.save( { a:1, b:0 } );
+
+explain = t.find( { a:{ $gte:0 }, b:{ $gte:0 } } ).explain( true );
+
+// We don't check explain.cursor because all plans perform the same.
+assert.eq( 2, explain.n );
+// nscanned and nscannedObjects are reported.
+assert.eq( 2, explain.nscanned );
+assert.eq( 2, explain.nscannedObjects );
+
+// A limit of 2.
+explain = t.find( { a:{ $gte:0 }, b:{ $gte:0 } } ).limit( -2 ).explain( true );
+assert.eq( 2, explain.n );
+
+// A $or query.
+explain = t.find( { $or:[ { a:{ $gte:0 }, b:{ $gte:1 } },
+                          { a:{ $gte:1 }, b:{ $gte:0 } } ] } ).explain( true );
+// One result from the first $or clause
+assert.eq( 1, explain.clauses[ 0 ].n );
+// But 2 total.
+assert.eq( 2, explain.n );
+
+// These are computed by summing the values for each clause.
+printjson(explain);
+assert.eq( 2, explain.n );
+
+// A non $or case where nscanned != number of results
+t.remove({});
+
+t.save( { a:'0', b:'1' } );
+t.save( { a:'1', b:'0' } );
+explain = t.find( { a:/0/, b:/1/ } ).explain( true );
+assert.eq( 1, explain.n );
+assert.eq( 2, explain.nscanned );