Expose per-level aggregated table properties via GetProperty()

Summary:
This patch adds "rocksdb.aggregated-table-properties"
and "rocksdb.aggregated-table-properties-at-levelN", the former
returns the aggreated table properties of a column family,
while the later returns the aggregated table properties
of the specified level N.

Test Plan: Added tests in db_test

Reviewers: igor, sdong, IslamAbdelRahman, anthony

Reviewed By: anthony

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45087

HISTORY.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+### New Features
+* DB::GetProperty() now accept "rocksdb.aggregated-table-properties" and "rocksdb.aggregated-table-properties-at-levelN", in which case it returns aggregated table properties of the target column family, or the aggregated table properties of the specified level N if the "at-level" version is used.
+
 ### Public API Changes
 * Removed class Env::RandomRWFile and Env::NewRandomRWFile().
 * Renamed DBOptions.num_subcompactions to DBOptions.max_subcompactions to make the name better match the actual funcionality of the option.

db/db_test.cc

@@ -468,6 +468,206 @@ TEST_F(DBTest, GetPropertiesOfAllTablesTest) {
   VerifyTableProperties(db_, 10 + 11 + 12 + 13);
 }
 
+namespace {
+void ResetTableProperties(TableProperties* tp) {
+  tp->data_size = 0;
+  tp->index_size = 0;
+  tp->filter_size = 0;
+  tp->raw_key_size = 0;
+  tp->raw_value_size = 0;
+  tp->num_data_blocks = 0;
+  tp->num_entries = 0;
+}
+
+void ParseTablePropertiesString(std::string tp_string, TableProperties* tp) {
+  double dummy_double;
+  std::replace(tp_string.begin(), tp_string.end(), ';', ' ');
+  std::replace(tp_string.begin(), tp_string.end(), '=', ' ');
+  ResetTableProperties(tp);
+
+  sscanf(tp_string.c_str(), "# data blocks %" SCNu64
+                            " # entries %" SCNu64
+                            " raw key size %" SCNu64
+                            " raw average key size %lf "
+                            " raw value size %" SCNu64
+                            " raw average value size %lf "
+                            " data block size %" SCNu64
+                            " index block size %" SCNu64
+                            " filter block size %" SCNu64,
+         &tp->num_data_blocks, &tp->num_entries, &tp->raw_key_size,
+         &dummy_double, &tp->raw_value_size, &dummy_double, &tp->data_size,
+         &tp->index_size, &tp->filter_size);
+}
+
+void VerifySimilar(uint64_t a, uint64_t b, double bias) {
+  ASSERT_EQ(a == 0U, b == 0U);
+  if (a == 0) {
+    return;
+  }
+  double dbl_a = static_cast<double>(a);
+  double dbl_b = static_cast<double>(b);
+  if (dbl_a > dbl_b) {
+    ASSERT_LT(static_cast<double>(dbl_a - dbl_b) / (dbl_a + dbl_b), bias);
+  } else {
+    ASSERT_LT(static_cast<double>(dbl_b - dbl_a) / (dbl_a + dbl_b), bias);
+  }
+}
+
+void VerifyTableProperties(const TableProperties& base_tp,
+                           const TableProperties& new_tp,
+                           double filter_size_bias = 0.1,
+                           double index_size_bias = 0.1,
+                           double data_size_bias = 0.1,
+                           double num_data_blocks_bias = 0.05) {
+  VerifySimilar(base_tp.data_size, new_tp.data_size, data_size_bias);
+  VerifySimilar(base_tp.index_size, new_tp.index_size, index_size_bias);
+  VerifySimilar(base_tp.filter_size, new_tp.filter_size, filter_size_bias);
+  VerifySimilar(base_tp.num_data_blocks, new_tp.num_data_blocks,
+                num_data_blocks_bias);
+  ASSERT_EQ(base_tp.raw_key_size, new_tp.raw_key_size);
+  ASSERT_EQ(base_tp.raw_value_size, new_tp.raw_value_size);
+  ASSERT_EQ(base_tp.num_entries, new_tp.num_entries);
+}
+
+void GetExpectedTableProperties(TableProperties* expected_tp,
+                                const int kKeySize, const int kValueSize,
+                                const int kKeysPerTable, const int kTableCount,
+                                const int kBloomBitsPerKey,
+                                const size_t kBlockSize) {
+  const int kKeyCount = kTableCount * kKeysPerTable;
+  const int kAvgSuccessorSize = kKeySize / 2;
+  const int kEncodingSavePerKey = kKeySize / 4;
+  expected_tp->raw_key_size = kKeyCount * (kKeySize + 8);
+  expected_tp->raw_value_size = kKeyCount * kValueSize;
+  expected_tp->num_entries = kKeyCount;
+  expected_tp->num_data_blocks =
+      kTableCount *
+      (kKeysPerTable * (kKeySize - kEncodingSavePerKey + kValueSize)) /
+      kBlockSize;
+  expected_tp->data_size =
+      kTableCount * (kKeysPerTable * (kKeySize + 8 + kValueSize));
+  expected_tp->index_size =
+      expected_tp->num_data_blocks * (kAvgSuccessorSize + 12);
+  expected_tp->filter_size =
+      kTableCount * (kKeysPerTable * kBloomBitsPerKey / 8);
+}
+}  // namespace
+
+TEST_F(DBTest, AggregatedTableProperties) {
+  for (int kTableCount = 40; kTableCount <= 100; kTableCount += 30) {
+    const int kKeysPerTable = 100;
+    const int kKeySize = 80;
+    const int kValueSize = 200;
+    const int kBloomBitsPerKey = 20;
+
+    Options options = CurrentOptions();
+    options.level0_file_num_compaction_trigger = 8;
+    options.compression = kNoCompression;
+    options.create_if_missing = true;
+
+    BlockBasedTableOptions table_options;
+    table_options.filter_policy.reset(
+        NewBloomFilterPolicy(kBloomBitsPerKey, false));
+    table_options.block_size = 1024;
+    options.table_factory.reset(new BlockBasedTableFactory(table_options));
+
+    DestroyAndReopen(options);
+
+    Random rnd(5632);
+    for (int table = 1; table <= kTableCount; ++table) {
+      for (int i = 0; i < kKeysPerTable; ++i) {
+        db_->Put(WriteOptions(), RandomString(&rnd, kKeySize),
+                 RandomString(&rnd, kValueSize));
+      }
+      db_->Flush(FlushOptions());
+    }
+    std::string property;
+    db_->GetProperty(DB::Properties::kAggregatedTableProperties, &property);
+
+    TableProperties expected_tp;
+    GetExpectedTableProperties(&expected_tp, kKeySize, kValueSize,
+                               kKeysPerTable, kTableCount, kBloomBitsPerKey,
+                               table_options.block_size);
+
+    TableProperties output_tp;
+    ParseTablePropertiesString(property, &output_tp);
+
+    VerifyTableProperties(expected_tp, output_tp);
+  }
+}
+
+TEST_F(DBTest, AggregatedTablePropertiesAtLevel) {
+  const int kTableCount = 100;
+  const int kKeysPerTable = 10;
+  const int kKeySize = 50;
+  const int kValueSize = 400;
+  const int kMaxLevel = 7;
+  const int kBloomBitsPerKey = 20;
+  Random rnd(301);
+  Options options = CurrentOptions();
+  options.level0_file_num_compaction_trigger = 8;
+  options.compression = kNoCompression;
+  options.create_if_missing = true;
+  options.level0_file_num_compaction_trigger = 2;
+  options.target_file_size_base = 8192;
+  options.max_bytes_for_level_base = 10000;
+  options.max_bytes_for_level_multiplier = 2;
+  // This ensures there no compaction happening when we call GetProperty().
+  options.disable_auto_compactions = true;
+
+  BlockBasedTableOptions table_options;
+  table_options.filter_policy.reset(
+      NewBloomFilterPolicy(kBloomBitsPerKey, false));
+  table_options.block_size = 1024;
+  options.table_factory.reset(new BlockBasedTableFactory(table_options));
+
+  DestroyAndReopen(options);
+
+  std::string level_tp_strings[kMaxLevel];
+  std::string tp_string;
+  TableProperties level_tps[kMaxLevel];
+  TableProperties tp, sum_tp, expected_tp;
+  for (int table = 1; table <= kTableCount; ++table) {
+    for (int i = 0; i < kKeysPerTable; ++i) {
+      db_->Put(WriteOptions(), RandomString(&rnd, kKeySize),
+               RandomString(&rnd, kValueSize));
+    }
+    db_->Flush(FlushOptions());
+    db_->CompactRange(CompactRangeOptions(), nullptr, nullptr);
+    ResetTableProperties(&sum_tp);
+    for (int level = 0; level < kMaxLevel; ++level) {
+      db_->GetProperty(
+          DB::Properties::kAggregatedTablePropertiesAtLevel + ToString(level),
+          &level_tp_strings[level]);
+      ParseTablePropertiesString(level_tp_strings[level], &level_tps[level]);
+      sum_tp.data_size += level_tps[level].data_size;
+      sum_tp.index_size += level_tps[level].index_size;
+      sum_tp.filter_size += level_tps[level].filter_size;
+      sum_tp.raw_key_size += level_tps[level].raw_key_size;
+      sum_tp.raw_value_size += level_tps[level].raw_value_size;
+      sum_tp.num_data_blocks += level_tps[level].num_data_blocks;
+      sum_tp.num_entries += level_tps[level].num_entries;
+    }
+    db_->GetProperty(DB::Properties::kAggregatedTableProperties, &tp_string);
+    ParseTablePropertiesString(tp_string, &tp);
+    ASSERT_EQ(sum_tp.data_size, tp.data_size);
+    ASSERT_EQ(sum_tp.index_size, tp.index_size);
+    ASSERT_EQ(sum_tp.filter_size, tp.filter_size);
+    ASSERT_EQ(sum_tp.raw_key_size, tp.raw_key_size);
+    ASSERT_EQ(sum_tp.raw_value_size, tp.raw_value_size);
+    ASSERT_EQ(sum_tp.num_data_blocks, tp.num_data_blocks);
+    ASSERT_EQ(sum_tp.num_entries, tp.num_entries);
+    if (table > 3) {
+      GetExpectedTableProperties(&expected_tp, kKeySize, kValueSize,
+                                 kKeysPerTable, table, kBloomBitsPerKey,
+                                 table_options.block_size);
+      // Gives larger bias here as index block size, filter block size,
+      // and data block size become much harder to estimate in this test.
+      VerifyTableProperties(tp, expected_tp, 0.5, 0.4, 0.4, 0.25);
+    }
+  }
+}
+
 class CoutingUserTblPropCollector : public TablePropertiesCollector {
  public:
   const char* Name() const override { return "CoutingUserTblPropCollector"; }

db/internal_stats.cc

@@ -13,6 +13,7 @@
 #endif
 
 #include <inttypes.h>
+#include <string>
 #include <algorithm>
 #include <vector>
 #include "db/column_family.h"
@@ -125,6 +126,10 @@ static const std::string base_level = "base-level";
 static const std::string total_sst_files_size = "total-sst-files-size";
 static const std::string estimate_pending_comp_bytes =
     "estimate-pending-compaction-bytes";
+static const std::string aggregated_table_properties =
+    "aggregated-table-properties";
+static const std::string aggregated_table_properties_at_level =
+    aggregated_table_properties + "-at-level";
 
 const std::string DB::Properties::kNumFilesAtLevelPrefix =
                       rocksdb_prefix + num_files_at_level_prefix;
@@ -172,6 +177,10 @@ const std::string DB::Properties::kTotalSstFilesSize =
                       rocksdb_prefix + total_sst_files_size;
 const std::string DB::Properties::kEstimatePendingCompactionBytes =
     rocksdb_prefix + estimate_pending_comp_bytes;
+const std::string DB::Properties::kAggregatedTableProperties =
+    rocksdb_prefix + aggregated_table_properties;
+const std::string DB::Properties::kAggregatedTablePropertiesAtLevel =
+    rocksdb_prefix + aggregated_table_properties_at_level;
 
 DBPropertyType GetPropertyType(const Slice& property, bool* is_int_property,
                                bool* need_out_of_mutex) {
@@ -198,6 +207,10 @@ DBPropertyType GetPropertyType(const Slice& property, bool* is_int_property,
     return kDBStats;
   } else if (in == sstables) {
     return kSsTables;
+  } else if (in == aggregated_table_properties) {
+    return kAggregatedTableProperties;
+  } else if (in.starts_with(aggregated_table_properties_at_level)) {
+    return kAggregatedTablePropertiesAtLevel;
   }
 
   *is_int_property = true;
@@ -328,6 +341,32 @@ bool InternalStats::GetStringProperty(DBPropertyType property_type,
     case kSsTables:
       *value = current->DebugString();
       return true;
+    case kAggregatedTableProperties: {
+      std::shared_ptr<const TableProperties> tp;
+      auto s = cfd_->current()->GetAggregatedTableProperties(&tp);
+      if (!s.ok()) {
+        return false;
+      }
+      *value = tp->ToString();
+      return true;
+    }
+    case kAggregatedTablePropertiesAtLevel: {
+      in.remove_prefix(
+          DB::Properties::kAggregatedTablePropertiesAtLevel.length());
+      uint64_t level;
+      bool ok = ConsumeDecimalNumber(&in, &level) && in.empty();
+      if (!ok || static_cast<int>(level) >= number_levels_) {
+        return false;
+      }
+      std::shared_ptr<const TableProperties> tp;
+      auto s = cfd_->current()->GetAggregatedTableProperties(
+          &tp, static_cast<int>(level));
+      if (!s.ok()) {
+        return false;
+      }
+      *value = tp->ToString();
+      return true;
+    }
     default:
       return false;
   }

db/internal_stats.h

@@ -64,6 +64,11 @@ enum DBPropertyType : uint32_t {
   kTotalSstFilesSize,               // Total size of all sst files.
   kBaseLevel,                       // The level that L0 data is compacted to
   kEstimatePendingCompactionBytes,  // Estimated bytes to compaction
+  kAggregatedTableProperties,  // Return a string that contains the aggregated
+                               // table properties.
+  kAggregatedTablePropertiesAtLevel,  // Return a string that contains the
+                                      // aggregated
+  // table properties at the specified level.
 };
 
 extern DBPropertyType GetPropertyType(const Slice& property,

db/version_set.cc

@@ -592,26 +592,58 @@ Status Version::GetTableProperties(std::shared_ptr<const TableProperties>* tp,
 }
 
 Status Version::GetPropertiesOfAllTables(TablePropertiesCollection* props) {
+  Status s;
   for (int level = 0; level < storage_info_.num_levels_; level++) {
-    for (const auto& file_meta : storage_info_.files_[level]) {
-      auto fname =
-          TableFileName(vset_->db_options_->db_paths, file_meta->fd.GetNumber(),
-                        file_meta->fd.GetPathId());
-      // 1. If the table is already present in table cache, load table
-      // properties from there.
-      std::shared_ptr<const TableProperties> table_properties;
-      Status s = GetTableProperties(&table_properties, file_meta, &fname);
-      if (s.ok()) {
-        props->insert({fname, table_properties});
-      } else {
-        return s;
-      }
+    s = GetPropertiesOfAllTables(props, level);
+    if (!s.ok()) {
+      return s;
     }
   }
 
   return Status::OK();
 }
 
+Status Version::GetPropertiesOfAllTables(TablePropertiesCollection* props,
+                                         int level) {
+  for (const auto& file_meta : storage_info_.files_[level]) {
+    auto fname =
+        TableFileName(vset_->db_options_->db_paths, file_meta->fd.GetNumber(),
+                      file_meta->fd.GetPathId());
+    // 1. If the table is already present in table cache, load table
+    // properties from there.
+    std::shared_ptr<const TableProperties> table_properties;
+    Status s = GetTableProperties(&table_properties, file_meta, &fname);
+    if (s.ok()) {
+      props->insert({fname, table_properties});
+    } else {
+      return s;
+    }
+  }
+
+  return Status::OK();
+}
+
+Status Version::GetAggregatedTableProperties(
+    std::shared_ptr<const TableProperties>* tp, int level) {
+  TablePropertiesCollection props;
+  Status s;
+  if (level < 0) {
+    s = GetPropertiesOfAllTables(&props);
+  } else {
+    s = GetPropertiesOfAllTables(&props, level);
+  }
+  if (!s.ok()) {
+    return s;
+  }
+
+  auto* new_tp = new TableProperties();
+  for (const auto& item : props) {
+    new_tp->Add(*item.second);
+  }
+  tp->reset(new_tp);
+  return Status::OK();
+}
+
 size_t Version::GetMemoryUsageByTableReaders() {
   size_t total_usage = 0;
   for (auto& file_level : storage_info_.level_files_brief_) {

db/version_set.h

@@ -462,6 +462,14 @@ class Version {
   // tables' propertis, represented as shared_ptr.
   Status GetPropertiesOfAllTables(TablePropertiesCollection* props);
 
+  Status GetPropertiesOfAllTables(TablePropertiesCollection* props, int level);
+
+  // REQUIRES: lock is held
+  // On success, "tp" will contains the aggregated table property amoug
+  // the table properties of all sst files in this version.
+  Status GetAggregatedTableProperties(
+      std::shared_ptr<const TableProperties>* tp, int level = -1);
+
   uint64_t GetEstimatedActiveKeys() {
     return storage_info_.GetEstimatedActiveKeys();
   }

include/rocksdb/db.h

@@ -361,6 +361,8 @@ class DB {
     static const std::string kEstimateLiveDataSize;
     static const std::string kTotalSstFilesSize;
     static const std::string kEstimatePendingCompactionBytes;
+    static const std::string kAggregatedTableProperties;
+    static const std::string kAggregatedTablePropertiesAtLevel;
   };
 #endif /* ROCKSDB_LITE */
 
@@ -394,6 +396,9 @@ class DB {
   //  "rocksdb.total-sst-files-size"
   //  "rocksdb.base-level"
   //  "rocksdb.estimate-pending-compaction-bytes"
+  //  "rocksdb.aggregated-table-properties"
+  //  "rocksdb.aggregated-table-properties-at-levelN", where "N" should be
+  //  replaced by the target level.
   virtual bool GetIntProperty(ColumnFamilyHandle* column_family,
                               const Slice& property, uint64_t* value) = 0;
   virtual bool GetIntProperty(const Slice& property, uint64_t* value) {

include/rocksdb/table_properties.h

@@ -61,6 +61,10 @@ struct TableProperties {
   //   @prop_delim: delimiter for each property.
   std::string ToString(const std::string& prop_delim = "; ",
                        const std::string& kv_delim = "=") const;
+
+  // Aggregate the numerical member variables of the specified
+  // TableProperties.
+  void Add(const TableProperties& tp);
 };
 
 // table properties' human-readable names in the property block.

table/table_properties.cc

@@ -74,6 +74,16 @@ std::string TableProperties::ToString(
   return result;
 }
 
+void TableProperties::Add(const TableProperties& tp) {
+  data_size += tp.data_size;
+  index_size += tp.index_size;
+  filter_size += tp.filter_size;
+  raw_key_size += tp.raw_key_size;
+  raw_value_size += tp.raw_value_size;
+  num_data_blocks += tp.num_data_blocks;
+  num_entries += tp.num_entries;
+}
+
 const std::string TablePropertiesNames::kDataSize  =
     "rocksdb.data.size";
 const std::string TablePropertiesNames::kIndexSize =