Revert "SERVER-53657 Add 'spillFileSizeBytes' and 'numBytesSpilledEstimate' to $group execution stats explain output"

This reverts commit 7cda7dd4df551cb5ff95b0a913b6dbb812320def.

6 files changed, 8 insertions, 35 deletions

diff --git a/src/mongo/db/exec/plan_stats.h b/src/mongo/db/exec/plan_stats.h
index 6ca25f01e69..8bf785a5b82 100644
--- a/src/mongo/db/exec/plan_stats.h
+++ b/src/mongo/db/exec/plan_stats.h
@@ -1040,14 +1040,6 @@ struct GroupStats : public SpecificStats {
     // Tracks an estimate of the total size of all documents output by the group stage in bytes.
     size_t totalOutputDataSizeBytes = 0;
 
-    // The size of the file spilled to disk. Note that this is not the same as the number of bytes
-    // spilled to disk, as any data spilled to disk will be compressed before being written to a
-    // file.
-    uint64_t spillFileSizeBytes = 0u;
-
-    // The number of bytes evicted from memory and spilled to disk.
-    uint64_t numBytesSpilledEstimate = 0u;
-
     // The number of times that we spilled data to disk while grouping the data.
     uint64_t spills = 0u;
 };
diff --git a/src/mongo/db/pipeline/document_source_group.cpp b/src/mongo/db/pipeline/document_source_group.cpp
index 34164f9efc9..13694a79a60 100644
--- a/src/mongo/db/pipeline/document_source_group.cpp
+++ b/src/mongo/db/pipeline/document_source_group.cpp
@@ -152,6 +152,7 @@ bool DocumentSourceGroup::shouldSpillWithAttemptToSaveMemory() {
                 "Exceeded memory limit for $group, but didn't allow external sort."
                 " Pass allowDiskUse:true to opt in.",
                 _memoryTracker._allowDiskUse);
+        _memoryTracker.resetCurrent();
         return true;
     }
     return false;
@@ -340,9 +341,6 @@ Value DocumentSourceGroup::serialize(boost::optional<ExplainOptions::Verbosity>
             Value(static_cast<long long>(_stats.totalOutputDataSizeBytes));
         out["usedDisk"] = Value(_stats.spills > 0);
         out["spills"] = Value(static_cast<long long>(_stats.spills));
-        out["spillFileSizeBytes"] = Value(static_cast<long long>(_stats.spillFileSizeBytes));
-        out["numBytesSpilledEstimate"] =
-            Value(static_cast<long long>(_stats.numBytesSpilledEstimate));
     }
 
     return Value(out.freezeToValue());
@@ -709,7 +707,6 @@ MONGO_COMPILER_NOINLINE DocumentSource::GetNextResult DocumentSourceGroup::initi
 
 shared_ptr<Sorter<Value, Value>::Iterator> DocumentSourceGroup::spill() {
     _stats.spills++;
-    _stats.numBytesSpilledEstimate += _memoryTracker.currentMemoryBytes();
 
     vector<const GroupsMap::value_type*> ptrs;  // using pointers to speed sorting
     ptrs.reserve(_groups->size());
@@ -721,12 +718,8 @@ shared_ptr<Sorter<Value, Value>::Iterator> DocumentSourceGroup::spill() {
 
     // Initialize '_file' in a lazy manner only when it is needed.
     if (!_file) {
-        // Only track stats about spilling when running in execution level explain.
-        if (pExpCtx->explain && *pExpCtx->explain >= ExplainOptions::Verbosity::kExecStats) {
-            _spillStats = std::make_unique<SorterFileStats>(nullptr /* sorterTracker */);
-        }
-        _file = std::make_shared<Sorter<Value, Value>::File>(
-            pExpCtx->tempDir + "/" + nextFileName(), _spillStats.get());
+        _file =
+            std::make_shared<Sorter<Value, Value>::File>(pExpCtx->tempDir + "/" + nextFileName());
     }
     SortedFileWriter<Value, Value> writer(SortOptions().TempDir(pExpCtx->tempDir), _file);
     switch (_accumulatedFields.size()) {  // same as ptrs[i]->second.size() for all i.
@@ -759,15 +752,13 @@ shared_ptr<Sorter<Value, Value>::Iterator> DocumentSourceGroup::spill() {
     metricsCollector.incrementSorterSpills(1);
 
     _groups->clear();
-
-    // Zero out the current per-accumulation statement memory consumption, as well as the
-    // current memory consumption, as the memory has been freed by spilling.
-    _memoryTracker.resetCurrent();
+    // Zero out the current per-accumulation statement memory consumption, as the memory has been
+    // freed by spilling.
+    for (const auto& accum : _accumulatedFields) {
+        _memoryTracker.set(accum.fieldName, 0);
+    }
 
     Sorter<Value, Value>::Iterator* iteratorPtr = writer.done();
-    if (_spillStats) {
-        _stats.spillFileSizeBytes = _spillStats->bytesSpilled();
-    }
     return shared_ptr<Sorter<Value, Value>::Iterator>(iteratorPtr);
 }
 
diff --git a/src/mongo/db/pipeline/document_source_group.h b/src/mongo/db/pipeline/document_source_group.h
index 9588037c48f..2a3ac2ea89c 100644
--- a/src/mongo/db/pipeline/document_source_group.h
+++ b/src/mongo/db/pipeline/document_source_group.h
@@ -323,8 +323,6 @@ private:
     // Only used when '_spilled' is true.
     std::unique_ptr<Sorter<Value, Value>::Iterator> _sorterIterator;
 
-    // Tracks the size of the spill file.
-    std::unique_ptr<SorterFileStats> _spillStats = nullptr;
     std::pair<Value, Value> _firstPartOfNextGroup;
 
     bool _sbeCompatible;
diff --git a/src/mongo/db/sorter/sorter_stats.cpp b/src/mongo/db/sorter/sorter_stats.cpp
index 6b4a33b5864..ec68b02efcd 100644
--- a/src/mongo/db/sorter/sorter_stats.cpp
+++ b/src/mongo/db/sorter/sorter_stats.cpp
@@ -52,7 +52,6 @@ void SorterStats::setSpilledRanges(long long spills) {
 SorterFileStats::SorterFileStats(SorterTracker* sorterTracker) : _sorterTracker(sorterTracker){};
 
 void SorterFileStats::addSpilledDataSize(long long data) {
-    _bytesSpilled += data;
     if (_sorterTracker) {
         _sorterTracker->bytesSpilled.fetchAndAdd(data);
     }
diff --git a/src/mongo/db/sorter/sorter_stats.h b/src/mongo/db/sorter/sorter_stats.h
index a536333e27f..05bfa8998d4 100644
--- a/src/mongo/db/sorter/sorter_stats.h
+++ b/src/mongo/db/sorter/sorter_stats.h
@@ -48,14 +48,8 @@ public:
     AtomicWord<long long> opened;
     AtomicWord<long long> closed;
 
-    long long bytesSpilled() const {
-        return _bytesSpilled;
-    }
-
 private:
     SorterTracker* _sorterTracker;
-
-    long long _bytesSpilled = 0;
 };
 
 class SorterStats {
diff --git a/src/mongo/db/sorter/sorter_test.cpp b/src/mongo/db/sorter/sorter_test.cpp
index 89f69eeeb61..12e433217ef 100644
--- a/src/mongo/db/sorter/sorter_test.cpp
+++ b/src/mongo/db/sorter/sorter_test.cpp
@@ -351,7 +351,6 @@ public:
         ASSERT_EQ(sorterFileStats.opened.load(), 2);
         ASSERT_EQ(sorterFileStats.closed.load(), 2);
         ASSERT_LTE(sorterTracker.bytesSpilled.load(), currentFileSize);
-        ASSERT_LTE(sorterFileStats.bytesSpilled(), currentFileSize);
 
         ASSERT(boost::filesystem::is_empty(tempDir.path()));
     }