Partial index isSubsetOf could be more precise for $or / $in

XMLWordPrintableJSON

    • Query Optimization
    • None
    • None
    • None
    • None
    • None
    • None
    • None

      When a partial filter expression uses $or, we sometimes don't recognize that it can satisfy a query using $or. For example:

      > db.c.createIndex({a: 1}, {partialFilterExpression: {$or: [ {a: {$lt: 0}}, {a: {$gt: 10}} ]}})
{
        "numIndexesBefore" : 1,
        "numIndexesAfter" : 2,
        "createdCollectionAutomatically" : true,
        "ok" : 1
}
> for (a=-2; a<15; ++a) db.c.insert({a})
WriteResult({ "nInserted" : 1 })
> db.c.find({$or: [ {a: -1}, {a: 12} ]}).explain()
{
    ...
                "winningPlan" : {
                        "stage" : "COLLSCAN",
    ...
}

      This query should use the index, because any document matching {a: -1} will be indexed, and any document matching {a: 12} will be indexed.

            Assignee:
            [DO NOT USE] Backlog - Query Optimization
            Reporter:
            David Percy (Inactive)
            Votes:
            1 Vote for this issue
            Watchers:
            9 Start watching this issue

              Created:
              Updated: