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// SERVER-393 Test indexed matching with $exists.
t = db.jstests_exists6;
t.drop();
t.ensureIndex( {b:1} );
t.save( {} );
t.save( {b:1} );
t.save( {b:null} );
checkExists = function( query ) {
// Index range constraint on 'b' is universal, so a BasicCursor is the default cursor type.
var x = t.find( query ).explain()
assert.eq( 'BasicCursor', x.cursor , tojson(x) );
// Index bounds include all elements.
var x = t.find( query ).hint( {b:1} ).explain()
if ( ! x.indexBounds ) x.indexBounds = {}
assert.eq( [ [ { $minElement:1 }, { $maxElement:1 } ] ], x.indexBounds.b , tojson(x) );
// All keys must be scanned.
assert.eq( 3, t.find( query ).hint( {b:1} ).explain().nscanned );
// 2 docs will match.
assert.eq( 2, t.find( query ).hint( {b:1} ).itcount() );
}
checkExists( {b:{$exists:true}} );
checkExists( {b:{$not:{$exists:false}}} );
checkMissing = function( query ) {
// Index range constraint on 'b' is not universal, so a BtreeCursor is the default cursor type.
assert.eq( 'BtreeCursor b_1', t.find( query ).explain().cursor );
// Scan null index keys.
assert.eq( [ [ null, null ] ], t.find( query ).explain().indexBounds.b );
// Two existing null keys will be scanned.
assert.eq( 2, t.find( query ).explain().nscanned );
// One doc is missing 'b'.
assert.eq( 1, t.find( query ).hint( {b:1} ).itcount() );
}
checkMissing( {b:{$exists:false}} );
checkMissing( {b:{$not:{$exists:true}}} );
// Now check existence of second compound field.
t.ensureIndex( {a:1,b:1} );
t.save( {a:1} );
t.save( {a:1,b:1} );
t.save( {a:1,b:null} );
checkExists = function( query ) {
// Index bounds include all elements.
assert.eq( [ [ { $minElement:1 }, { $maxElement:1 } ] ], t.find( query ).explain().indexBounds.b );
// All keys must be scanned.
assert.eq( 3, t.find( query ).explain().nscanned );
// 2 docs will match.
assert.eq( 2, t.find( query ).hint( {a:1,b:1} ).itcount() );
}
checkExists( {a:1,b:{$exists:true}} );
checkExists( {a:1,b:{$not:{$exists:false}}} );
checkMissing = function( query ) {
// Scan null index keys.
assert.eq( [ [ null, null ] ], t.find( query ).explain().indexBounds.b );
// Two existing null keys will be scanned.
assert.eq( 2, t.find( query ).explain().nscanned );
// One doc is missing 'b'.
assert.eq( 1, t.find( query ).hint( {a:1,b:1} ).itcount() );
}
checkMissing( {a:1,b:{$exists:false}} );
checkMissing( {a:1,b:{$not:{$exists:true}}} );
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