Details
Major - P3 Description
The test runs this aggregate command:
[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] ----
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] testing command {
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] "mapReduce" : "foo",
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] "map" : function() {
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] emit(this.x, 1);
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] },
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] "reduce" : function(key, values) {
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] return Array.sum(values);
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] },
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] "out" : {
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] "inline" : 1
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] }
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] }
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[js_test:safe_secondary_reads_single_migration_waitForDelete] [jsTest] ----
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We expect that there's exactly one operation in the profiler matching this query:
{
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"command.shardVersion" : {
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"$exists" : true
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},
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"command.shardVersion.0" : {
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"$ne" : Timestamp(0, 0)
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},
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"command.shardVersion.1" : {
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"$ne" : ObjectId("00000000ffffffffffffffff")
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},
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"command.$readPreference" : {
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"mode" : "secondary"
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},
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"command.readConcern" : {
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"level" : "local"
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},
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"errCode" : {
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"$ne" : 13388
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},
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"command.aggregate" : "foo"
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}
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However, the profiler has two matching aggregate commands out of four entries total (two aggregates, a getMore, and the find itself on system.profile).
Here's the first aggregate for the mapreduce command:
{
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"op" : "command",
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"ns" : "test.foo",
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"command" : {
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"aggregate" : "foo",
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"pipeline" : [
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{
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"$project" : {
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"emits" : {
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"$_internalJsEmit" : {
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"eval" : "function() {\n emit(this.x, 1);\n }",
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"this" : "$$ROOT"
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}
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},
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"_id" : false
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}
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},
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{
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"$unwind" : {
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"path" : "$emits"
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}
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},
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{
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"$group" : {
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"_id" : "$emits.k",
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"value" : {
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"$_internalJsReduce" : {
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"data" : "$emits",
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"eval" : "function(key, values) {\n return Array.sum(values);\n }"
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}
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}
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}
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}
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],
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"cursor" : {
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"batchSize" : 0
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},
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"allowDiskUse" : true,
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"fromMongos" : true,
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"let" : {
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"IS_MR" : true,
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"NOW" : ISODate("2021-04-12T22:19:31.033Z"),
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"CLUSTER_TIME" : Timestamp(1618265970, 87)
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},
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"isMapReduceCommand" : true,
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"$queryOptions" : {
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"$readPreference" : {
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"mode" : "secondary"
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}
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},
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"readConcern" : {
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"level" : "local"
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},
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"needsMerge" : true,
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// etc...
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The other aggregate command is a $mergeCursors:
"op" : "command",
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"ns" : "test.foo",
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"command" : {
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"aggregate" : "foo",
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"pipeline" : [
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{
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"$mergeCursors" : {
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"lsid" : {
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"id" : UUID("16770975-1dd1-4392-b907-948771436821"),
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"uid" : BinData(0,"47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=")
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},
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"compareWholeSortKey" : false,
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"remotes" : [
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{
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"shardId" : "safe_secondary_reads_single_migration_waitForDelete-rs0",
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"hostAndPort" : "ip-10-122-47-239.ec2.internal:21521",
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"cursorResponse" : {
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"cursor" : {
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"id" : NumberLong("2479107308808163874"),
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"ns" : "test.foo",
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"firstBatch" : [ ]
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},
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"ok" : 1
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}
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},
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{
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"shardId" : "safe_secondary_reads_single_migration_waitForDelete-rs1",
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"hostAndPort" : "ip-10-122-47-239.ec2.internal:21523",
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"cursorResponse" : {
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"cursor" : {
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"id" : NumberLong("497587830264602086"),
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"ns" : "test.foo",
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"firstBatch" : [ ]
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},
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"ok" : 1
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}
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}
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],
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"tailableMode" : "normal",
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"nss" : "test.foo",
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"allowPartialResults" : false,
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"recordRemoteOpWaitTime" : true
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}
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},
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{
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"$group" : {
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"_id" : "$$ROOT._id",
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"value" : {
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"$_internalJsReduce" : {
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"data" : "$$ROOT.value",
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"eval" : "function(key, values) {\n return Array.sum(values);\n }"
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}
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},
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"$doingMerge" : true
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}
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}
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],
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The full output is very large so full logs are attached to the ticket in their entirety.