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POWhat does the nscannedObjectsAllPlans in MongoDb explain mean
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  1. POWhat does the nscannedObjectsAllPlans in MongoDb explain mean
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    copied!<p>Im trying to examine a query and Im not sure what "nscannedObjectsAllPlans" and "nscannedAllPlans" is doing because I see that if I run a query directly off an indexed field "purchaseState"</p> <p>I get the same results scanned items for "<strong>nscannedObjects</strong>", "<strong>nscanned</strong>", "<strong>nscannedObjectsAllPlans</strong>", and "<strong>nscannedAllPlans</strong>"</p> <p>However once I added price greater than 400 into the query the <strong>nscannedObjectsAllPlans</strong> is now greater than the <strong>nscannedObjects</strong> I wanted to know if <strong>nscannedObjectsAllPlans</strong> is the total number of scanned objects that running a plan with the purchase_state index along with the purchase_state_Id index? or is it just stating the Greater of the two index plan results??</p> <p>I added an index to pruchase state then I added an index on purchase state and Id</p> <p>db.toys.ensureIndex({"purchaseState" : 1})</p> <p>db.toys.ensureIndex({"purchaseState" : 1, "_id" : 1})</p> <pre><code> **db.toys.find({"purchaseState" : "NY"}).pretty().explain()** "cursor" : "BtreeCursor purchaseState_1", "isMultiKey" : false, "n" : 1596, "nscannedObjects" : 1596, "nscanned" : 1596, "nscannedObjectsAllPlans" : 1596, "nscannedAllPlans" : 1596, "scanAndOrder" : false, "indexOnly" : false, "nYields" : 0, "nChunkSkips" : 0, "millis" : 3, "indexBounds" : { "purchaseState" : [ [ "NY", "NY" ] ] }, "server" : "XXXXXXX:27017" **db.toys.find({"purchaseState" : "NY", "price": { $gt : 400 }}).pretty().explain()** "cursor" : "BtreeCursor purchaseState_1", "isMultiKey" : false, "n" : 1423, "nscannedObjects" : 1596, "nscanned" : 1596, "nscannedObjectsAllPlans" : 1808, "nscannedAllPlans" : 1808, "scanAndOrder" : false, "indexOnly" : false, "nYields" : 0, "nChunkSkips" : 0, "millis" : 10, "indexBounds" : { "purchaseState" : [ [ "NY", "NY" ] ] }, "server" : "XXXXXXX:27017" </code></pre>
 

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