Mongodb find() query criteria implicit AND? - mongodb

Question

Given the query
var p_other = 111;
var p_timestamp = ISODate("2015-05-08T07:00:00.000Z");
db.test.find({
other: p_other,
$or: [
{ "startTime": null },
{ "startTime": { $lte: p_timestamp }}
],
$or: [
{ "endTime": null },
{ "endTime": { $gte: p_timestamp }}
]
})
on the following data:
{
"_id" : "1",
"other" : 111,
"startTime" : ISODate("2015-05-08T07:01:30.868Z")
}
{
"_id" : "2",
"other" : 111,
"startTime" : ISODate("2015-05-08T06:04:30.040Z"),
"endTime" : ISODate("2015-05-08T07:01:30.868Z")
}
Both docs are returned, where I would expect only the second one.
Running an explain() I get the following parsed query:
"parsedQuery" : {
"$and" : [
{
"$or" : [
{
"endTime" : {
"$eq" : null
}
},
{
"endTime" : {
"$gte" : ISODate("2015-05-08T07:00:00.000Z")
}
}
]
},
{
"other" : {
"$eq" : 111
}
}
]
}
What's the reason the first $or is ignored?
From what I know, there should be an implicit AND between the criteria expressions of a find(), although this is not mentioned in the doc (at least not here).
The only mention regarding the usage of multiple $or is in the $and doc:
This query cannot be constructed using an implicit AND operation,
because it uses the $or operator more than once.
But either I don't understand it or this is not really an explanation :-)

Answer 1

Please read document of $and carefully. You will find following-
The query cannot be constructed using an implicit AND operation, when it uses the $or operator multiple times.
Following query will give you desired result :
var p_other = 111;
var p_timestamp = ISODate("2015-05-08T07:00:00.000Z");
db.collection.find({
other: p_other,
$and: [{
$or: [{
"startTime": null
}, {
"startTime": {
$lte: p_timestamp
}
}]
}, {
$or: [{
"endTime": null
}, {
"endTime": {
$gte: p_timestamp
}
}]
}]
})