Details
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Bug
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Status: Closed
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Major - P3
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Resolution: Works as Designed
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2.0.1
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None
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None
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.NET 4.5, Azure, Windows
Description
I have been porting our repository layer to use the new driver (2.0.1), and in doing so we have noticed some performance degradation with the new driver. Upon investigating where we potentially went wrong I went back to the old code to capture the queries logged in the profiler database to compare against what is now being generated by the new driver.
NOTE: We are using database version 3.0.4.
In the queries generated by the new driver the LIMIT stage of the query is no longer honored, and thus not reported as part of the query execution plan.
(new driver code/log below...)
Legacy driver code:
var query = Query<Tenant>.EQ(e => e.Name, name);
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var found = this.retryHandler.ExecuteFunc(() => this.Collection.FindOne(query));
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return found;
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Logged in profiler database for legacy code:
{
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"op" : "query",
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"ns" : "dfl.tenants",
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"query" : {
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"Name" : "dev"
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},
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"ntoskip" : 0,
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"nscanned" : 1,
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"nscannedObjects" : 1,
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"keyUpdates" : 0,
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"writeConflicts" : 0,
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"numYield" : 0,
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"locks" : {
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"Global" : {
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"acquireCount" : {
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"r" : NumberLong(2)
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}
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},
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"MMAPV1Journal" : {
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"acquireCount" : {
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"r" : NumberLong(1)
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}
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},
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"Database" : {
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"acquireCount" : {
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"r" : NumberLong(1)
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}
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},
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"Collection" : {
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"acquireCount" : {
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"R" : NumberLong(1)
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}
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}
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},
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"nreturned" : 1,
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"responseLength" : 103,
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"millis" : 0,
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"execStats" : {
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"stage" : "LIMIT",
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"nReturned" : 1,
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"executionTimeMillisEstimate" : 0,
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"works" : 1,
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"advanced" : 1,
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"needTime" : 0,
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"needFetch" : 0,
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"saveState" : 0,
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"restoreState" : 0,
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"isEOF" : 1,
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"invalidates" : 0,
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"limitAmount" : 0,
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"inputStage" : {
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"stage" : "FETCH",
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"nReturned" : 1,
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"executionTimeMillisEstimate" : 0,
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"works" : 1,
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"advanced" : 1,
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"needTime" : 0,
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"needFetch" : 0,
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"saveState" : 0,
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"restoreState" : 0,
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"isEOF" : 1,
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"invalidates" : 0,
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"docsExamined" : 1,
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"alreadyHasObj" : 0,
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"inputStage" : {
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"stage" : "IXSCAN",
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"nReturned" : 1,
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"executionTimeMillisEstimate" : 0,
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"works" : 1,
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"advanced" : 1,
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"needTime" : 0,
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"needFetch" : 0,
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"saveState" : 0,
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"restoreState" : 0,
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"isEOF" : 1,
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"invalidates" : 0,
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"keyPattern" : {
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"Name" : 1
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},
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"indexName" : "Name_1",
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"isMultiKey" : false,
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"direction" : "forward",
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"indexBounds" : {
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"Name" : [
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"[\"dev\", \"dev\"]"
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]
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},
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"keysExamined" : 1,
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"dupsTested" : 0,
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"dupsDropped" : 0,
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"seenInvalidated" : 0,
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"matchTested" : 0
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}
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}
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},
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"ts" : ISODate("2015-10-14T18:34:08.919Z"),
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"client" : "127.0.0.1",
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"allUsers" : [],
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"user" : ""
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}
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New driver code:
var filter = Builders<Tenant>.Filter.Eq(e => e.Name, name);
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var find = this.Collection.Find(filter).Limit(1);
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return await this.retryHandler.ExecuteFuncAsync(() => find.SingleOrDefaultAsync()).ConfigureAwait(false);
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Logged in profiler database for new code:
{
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"op" : "query",
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"ns" : "dfl.tenants",
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"query" : {
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"$query" : {
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"Name" : "dev"
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}
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},
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"ntoreturn" : 1,
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"ntoskip" : 0,
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"nscanned" : 1,
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"nscannedObjects" : 1,
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"keyUpdates" : 0,
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"writeConflicts" : 0,
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"numYield" : 0,
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"locks" : {
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"Global" : {
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"acquireCount" : {
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"r" : NumberLong(2)
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}
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},
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"MMAPV1Journal" : {
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"acquireCount" : {
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"r" : NumberLong(1)
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}
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},
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"Database" : {
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"acquireCount" : {
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"r" : NumberLong(1)
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}
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},
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"Collection" : {
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"acquireCount" : {
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"R" : NumberLong(1)
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}
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}
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},
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"nreturned" : 1,
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"responseLength" : 103,
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"millis" : 0,
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"execStats" : {
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"stage" : "FETCH",
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"nReturned" : 1,
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"executionTimeMillisEstimate" : 0,
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"works" : 1,
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"advanced" : 1,
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"needTime" : 0,
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"needFetch" : 0,
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"saveState" : 0,
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"restoreState" : 0,
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"isEOF" : 1,
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"invalidates" : 0,
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"docsExamined" : 1,
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"alreadyHasObj" : 0,
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"inputStage" : {
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"stage" : "IXSCAN",
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"nReturned" : 1,
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"executionTimeMillisEstimate" : 0,
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"works" : 1,
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"advanced" : 1,
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"needTime" : 0,
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"needFetch" : 0,
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"saveState" : 0,
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"restoreState" : 0,
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"isEOF" : 1,
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"invalidates" : 0,
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"keyPattern" : {
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"Name" : 1
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},
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"indexName" : "Name_1",
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"isMultiKey" : false,
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"direction" : "forward",
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"indexBounds" : {
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"Name" : [
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"[\"dev\", \"dev\"]"
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]
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},
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"keysExamined" : 1,
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"dupsTested" : 0,
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"dupsDropped" : 0,
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"seenInvalidated" : 0,
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"matchTested" : 0
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}
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},
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"ts" : ISODate("2015-10-14T20:18:23.168Z"),
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"client" : "127.0.0.1",
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"allUsers" : [],
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"user" : ""
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}
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