Info

explain output from 2.5.4 indicates that an in-memory sort (scanAndSort=true) is used to order results of $not query. The result set is large enough that it is hitting the internal limit of the in-memory sort - see assertion message. This is different from 2.5.3 where the query optimizer is able to utilize the index (scanAndSort=false). After updating from 2.5.3 to 2.5.4 start to get error messages for quires with sorting: query: {[db.photos.find({ $or: [ { r1: 1, s: 5 } , { r1: 3, s: { $ne: 9 } } ] }).sort( {sdate: -1} , {_id:0, cid: 1}).limit(30).explain()}} indexes { "v" : 1, "key" : { "sdate" : 1 } , "name" : "sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r0" : 1 } , "name" : "r0_1", "ns" : "pastvu.photos", "sparse" : true, "background" : true, "safe" : null } { "v" : 1, "key" : { "r1" : 1 } , "name" : "r1_1", "ns" : "pastvu.photos", "sparse" : true, "background" : true, "safe" : null } { "v" : 1, "key" : { "r2" : 1 } , "name" : "r2_1", "ns" : "pastvu.photos", "sparse" : true, "background" : true, "safe" : null } { "v" : 1, "key" : { "r3" : 1 } , "name" : "r3_1", "ns" : "pastvu.photos", "sparse" : true, "background" : true, "safe" : null } { "v" : 1, "key" : { "r4" : 1 } , "name" : "r4_1", "ns" : "pastvu.photos", "sparse" : true, "background" : true, "safe" : null } { "v" : 1, "key" : { "s" : 1 } , "name" : "s_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r0" : 1, "sdate" : 1 } , "name" : "r0_1_sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r1" : 1, "sdate" : 1 } , "name" : "r1_1_sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r2" : 1, "sdate" : 1 } , "name" : "r2_1_sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r3" : 1, "sdate" : 1 } , "name" : "r3_1_sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } { "v" : 1, "key" : { "r4" : 1, "sdate" : 1 } , "name" : "r4_1_sdate_1", "ns" : "pastvu.photos", "background" : true, "safe" : null } 2.5.3: { "cursor" : "BtreeCursor sdate_1 reverse", "isMultiKey" : false, "n" : 30, "nscannedObjects" : 270, "nscanned" : 270, "nscannedObjectsAllPlans" : 270, "nscannedAllPlans" : 270, "scanAndOrder" : false, "indexOnly" : false, "nYields" : 0, "nChunkSkips" : 0, "millis" : 116, "indexBounds" : { "sdate" : [ [ { "$maxElement" : 1 } , { "$minElement" : 1 } ] ] } } 2.5.4: 2013-11-23T19:37:02.040+0400 error: { "$err" : "Runner error, memory limit for sort probably exceeded", "code" : 17144 } at src/mongo/shell/query.js:131

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