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Type:
Bug
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Resolution: Unresolved
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Priority:
Major - P3
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None
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Affects Version/s: 3.0.8, 3.2.1
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Query Execution
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ALL
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Query 15 (06/03/16), QE 2022-10-17, QE 2022-10-31, QE 2022-11-14, QE 2022-11-28, QE 2022-12-12, QE 2022-12-26, QE 2023-01-09
With following index:
db.c.createIndex({p: "2dsphere", s: 1})
and 10M of the following documents:
x = ''
for (i=0; i<1000; i++)
x += 'x'
doc = {p: [0,0], s: 0, x: x}
run following query, which finds 0 documents:
db.c.find({
p: {
$near: {
$geometry: {
coordinates: [1, 0],
type: "Point"
},
},
},
s: {$ne: 0}
}).itcount()
}
Result as follows:
- peak memory usage is about 13 GB in excess of WT cache
- query has scanned 20M documents to return 0, in spite of index. Changing query to e.g. s: 1 instead of s: {$ne: 0} eliminates document scan and excess memory usage.
- less highly skewed point distribution reduces problem presumably because skewed distribution requires accumulating all documents in memory for sort
- is duplicated by
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SERVER-32180 mongod oom with low connections
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- Closed
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- is related to
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SERVER-20239 Built-in sampling heap profiler
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- Closed
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- related to
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- Investigating
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- Closed
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