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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: 2.0.4
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Component/s: None
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Labels:None
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ALL
If an attempt is made to clear the recorded index for the query plan of an unsatisfiable query, an assertion is raised because in 2.0 a query pattern cannot be generated for an unsatisfiable query.
In 2.1 a query pattern can be generated for an unsatisfiable query, so the issue no longer exists in 2.1.
t = db.t;
t.drop();
t.ensureIndex( { a:1 } );
t.ensureIndex( { b:1 } );
for( i = 0; i < 25; ++i ) {
t.save( { a:0, b:'' } );
}
big = new Array( 1000000 ).toString();
for( i = 0; i < 50; ++i ) {
t.save( { a:[1,3], b:big } );
}
// Record the a:1 index for the query pattern for { a: { $lt:1 } }, { b:1 }.
assert.eq( 'BtreeCursor a_1', t.find( { a:{ $lt:1 } } ).sort( { b:1 } ).explain().cursor );
// The multikey query pattern for this query will match that of the previous query.
// The a:1 index will be retried for this query but fail because an in memory sort must
// be performed on a larger data set. This causes the single key query pattern for
// { a:{ $lt:2, $gt:2 } }, { b:1 } to be cleared.
assert.lt( -1, t.find( { a:{ $lt:2, $gt:2 } } ).sort( { b:1 } ).itcount() );