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rocksdb/db/range_tombstone_fragmenter_...

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Use only "local" range tombstones during Get (#4449) Summary: Previously, range tombstones were accumulated from every level, which was necessary if a range tombstone in a higher level covered a key in a lower level. However, RangeDelAggregator::AddTombstones's complexity is based on the number of tombstones that are currently stored in it, which is wasteful in the Get case, where we only need to know the highest sequence number of range tombstones that cover the key from higher levels, and compute the highest covering sequence number at the current level. This change introduces this optimization, and removes the use of RangeDelAggregator from the Get path. In the benchmark results, the following command was used to initialize the database: ``` ./db_bench -db=/dev/shm/5k-rts -use_existing_db=false -benchmarks=filluniquerandom -write_buffer_size=1048576 -compression_type=lz4 -target_file_size_base=1048576 -max_bytes_for_level_base=4194304 -value_size=112 -key_size=16 -block_size=4096 -level_compaction_dynamic_level_bytes=true -num=5000000 -max_background_jobs=12 -benchmark_write_rate_limit=20971520 -range_tombstone_width=100 -writes_per_range_tombstone=100 -max_num_range_tombstones=50000 -bloom_bits=8 ``` ...and the following command was used to measure read throughput: ``` ./db_bench -db=/dev/shm/5k-rts/ -use_existing_db=true -benchmarks=readrandom -disable_auto_compactions=true -num=5000000 -reads=100000 -threads=32 ``` The filluniquerandom command was only run once, and the resulting database was used to measure read performance before and after the PR. Both binaries were compiled with `DEBUG_LEVEL=0`. Readrandom results before PR: ``` readrandom : 4.544 micros/op 220090 ops/sec; 16.9 MB/s (63103 of 100000 found) ``` Readrandom results after PR: ``` readrandom : 11.147 micros/op 89707 ops/sec; 6.9 MB/s (63103 of 100000 found) ``` So it's actually slower right now, but this PR paves the way for future optimizations (see #4493). ---- Pull Request resolved: https://github.com/facebook/rocksdb/pull/4449 Differential Revision: D10370575 Pulled By: abhimadan fbshipit-source-id: 9a2e152be1ef36969055c0e9eb4beb0d96c11f4d
6 years ago
// Copyright (c) 2018-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "db/range_tombstone_fragmenter.h"
#include "db/db_test_util.h"
#include "rocksdb/comparator.h"
#include "util/testutil.h"
namespace rocksdb {
class RangeTombstoneFragmenterTest : public testing::Test {};
namespace {
static auto bytewise_icmp = InternalKeyComparator(BytewiseComparator());
std::unique_ptr<InternalIterator> MakeRangeDelIter(
const std::vector<RangeTombstone>& range_dels) {
std::vector<std::string> keys, values;
for (const auto& range_del : range_dels) {
auto key_and_value = range_del.Serialize();
keys.push_back(key_and_value.first.Encode().ToString());
values.push_back(key_and_value.second.ToString());
}
return std::unique_ptr<test::VectorIterator>(
new test::VectorIterator(keys, values));
}
void VerifyFragmentedRangeDels(
FragmentedRangeTombstoneIterator* iter,
const std::vector<RangeTombstone>& expected_tombstones) {
iter->SeekToFirst();
for (size_t i = 0; i < expected_tombstones.size() && iter->Valid();
i++, iter->Next()) {
EXPECT_EQ(ExtractUserKey(iter->key()), expected_tombstones[i].start_key_);
EXPECT_EQ(iter->value(), expected_tombstones[i].end_key_);
EXPECT_EQ(GetInternalKeySeqno(iter->key()), expected_tombstones[i].seq_);
}
EXPECT_FALSE(iter->Valid());
}
struct SeekForPrevTestCase {
Slice seek_target;
RangeTombstone expected_position;
bool out_of_range;
};
void VerifySeekForPrev(FragmentedRangeTombstoneIterator* iter,
const std::vector<SeekForPrevTestCase>& cases) {
for (const auto& testcase : cases) {
InternalKey ikey_seek_target(testcase.seek_target, 0, kTypeRangeDeletion);
iter->SeekForPrev(ikey_seek_target.Encode());
if (testcase.out_of_range) {
ASSERT_FALSE(iter->Valid());
} else {
ASSERT_TRUE(iter->Valid());
EXPECT_EQ(ExtractUserKey(iter->key()),
testcase.expected_position.start_key_);
EXPECT_EQ(iter->value(), testcase.expected_position.end_key_);
EXPECT_EQ(GetInternalKeySeqno(iter->key()),
testcase.expected_position.seq_);
}
}
}
struct MaxCoveringTombstoneSeqnumTestCase {
Slice user_key;
int result;
};
void VerifyMaxCoveringTombstoneSeqnum(
FragmentedRangeTombstoneIterator* iter, const Comparator* ucmp,
const std::vector<MaxCoveringTombstoneSeqnumTestCase>& cases) {
for (const auto& testcase : cases) {
InternalKey key_and_snapshot(testcase.user_key, kMaxSequenceNumber,
kTypeValue);
EXPECT_EQ(testcase.result, MaxCoveringTombstoneSeqnum(
iter, key_and_snapshot.Encode(), ucmp));
}
}
} // anonymous namespace
TEST_F(RangeTombstoneFragmenterTest, NonOverlappingTombstones) {
auto range_del_iter = MakeRangeDelIter({{"a", "b", 10}, {"c", "d", 5}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter, {{"a", "b", 10}, {"c", "d", 5}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"", 0}, {"a", 10}, {"b", 0}, {"c", 5}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlappingTombstones) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10}, {"c", "g", 15}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter,
{{"a", "c", 10}, {"c", "e", 15}, {"e", "g", 15}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"a", 10}, {"c", 15}, {"e", 15}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, ContiguousTombstones) {
auto range_del_iter = MakeRangeDelIter(
{{"a", "c", 10}, {"c", "e", 20}, {"c", "e", 5}, {"e", "g", 15}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter,
{{"a", "c", 10}, {"c", "e", 20}, {"e", "g", 15}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"a", 10}, {"c", 20}, {"e", 15}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartAndEndKey) {
auto range_del_iter =
MakeRangeDelIter({{"a", "c", 10}, {"a", "c", 7}, {"a", "c", 3}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"a", 10}, {"b", 10}, {"c", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartKeyDifferentEndKeys) {
auto range_del_iter =
MakeRangeDelIter({{"a", "e", 10}, {"a", "g", 7}, {"a", "c", 3}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter,
{{"a", "c", 10}, {"c", "e", 10}, {"e", "g", 7}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"a", 10}, {"c", 10}, {"e", 7}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartKeyMixedEndKeys) {
auto range_del_iter = MakeRangeDelIter({{"a", "c", 30},
{"a", "g", 20},
{"a", "e", 10},
{"a", "g", 7},
{"a", "c", 3}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter,
{{"a", "c", 30}, {"c", "e", 20}, {"e", "g", 20}});
VerifyMaxCoveringTombstoneSeqnum(&iter, bytewise_icmp.user_comparator(),
{{"a", 30}, {"c", 20}, {"e", 20}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKey) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10},
{"c", "e", 10},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter, bytewise_icmp.user_comparator(),
{{"a", 10}, {"c", 10}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKeyWithSnapshot) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, 9);
VerifyFragmentedRangeDels(
&iter, {{"c", "g", 8}, {"g", "i", 6}, {"j", "l", 4}, {"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter, bytewise_icmp.user_comparator(),
{{"a", 0}, {"c", 8}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKeyUnordered) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, 9);
VerifyFragmentedRangeDels(
&iter, {{"c", "g", 8}, {"g", "i", 6}, {"j", "l", 4}, {"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter, bytewise_icmp.user_comparator(),
{{"a", 0}, {"c", 8}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekForPrevStartKey) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifySeekForPrev(
&iter,
{{"a", {"a", "c", 10}}, {"e", {"e", "g", 8}}, {"l", {"l", "n", 4}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekForPrevCovered) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifySeekForPrev(
&iter,
{{"b", {"a", "c", 10}}, {"f", {"e", "g", 8}}, {"m", {"l", "n", 4}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekForPrevEndKey) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifySeekForPrev(&iter, {{"c", {"c", "e", 10}},
{"g", {"g", "i", 6}},
{"i", {"g", "i", 6}},
{"n", {"l", "n", 4}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekForPrevOutOfBounds) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneIterator iter(std::move(range_del_iter),
bytewise_icmp, kMaxSequenceNumber);
VerifySeekForPrev(&iter,
{{"", {}, true /* out of range */}, {"z", {"l", "n", 4}}});
}
} // namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}