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[opt](MergeIO) use equivalent merge size to measure merge effectiveness #26923

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Merged
morningman merged 1 commit into from
Nov 14, 2023
Merged

[opt](MergeIO) use equivalent merge size to measure merge effectiveness #26923

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8 changes: 5 additions & 3 deletions be/src/io/fs/buffered_reader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -152,7 +152,6 @@ Status MergeRangeFileReader::read_at_impl(size_t offset, Slice result, size_t* b
}
content_size = 0;
hollow_size = 0;
double amplified_ratio = config::max_amplified_read_ratio;
std::vector<std::pair<double, size_t>> ratio_and_size;
// Calculate the read amplified ratio for each merge operation and the size of the merged data.
// Find the largest size of the merged data whose amplified ratio is less than config::max_amplified_read_ratio
Expand All @@ -168,9 +167,12 @@ Status MergeRangeFileReader::read_at_impl(size_t offset, Slice result, size_t* b
}
}
size_t best_merged_size = 0;
for (const std::pair<double, size_t>& rs : ratio_and_size) {
for (int i = 0; i < ratio_and_size.size(); ++i) {
const std::pair<double, size_t>& rs = ratio_and_size[i];
size_t equivalent_size = rs.second / (i + 1);
if (rs.second > best_merged_size) {
if (rs.first < amplified_ratio || rs.second <= MIN_READ_SIZE) {
if (rs.first <= _max_amplified_ratio ||
(_max_amplified_ratio < 1 && equivalent_size <= _equivalent_io_size)) {
best_merged_size = rs.second;
}
}
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11 changes: 10 additions & 1 deletion be/src/io/fs/buffered_reader.h
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Expand Up @@ -131,8 +131,9 @@ class MergeRangeFileReader : public io::FileReader {
static constexpr size_t READ_SLICE_SIZE = 8 * 1024 * 1024; // 8MB
static constexpr size_t BOX_SIZE = 1 * 1024 * 1024; // 1MB
static constexpr size_t SMALL_IO = 2 * 1024 * 1024; // 2MB
static constexpr size_t HDFS_MIN_IO_SIZE = 4 * 1024; // 4KB
static constexpr size_t OSS_MIN_IO_SIZE = 512 * 1024; // 512KB
static constexpr size_t NUM_BOX = TOTAL_BUFFER_SIZE / BOX_SIZE; // 128
static constexpr size_t MIN_READ_SIZE = 4096; // 4KB

MergeRangeFileReader(RuntimeProfile* profile, io::FileReaderSPtr reader,
const std::vector<PrefetchRange>& random_access_ranges)
Expand All @@ -142,6 +143,11 @@ class MergeRangeFileReader : public io::FileReader {
_range_cached_data.resize(random_access_ranges.size());
_size = _reader->size();
_remaining = TOTAL_BUFFER_SIZE;
_is_oss = typeid_cast<io::S3FileReader*>(_reader.get()) != nullptr;
_max_amplified_ratio = config::max_amplified_read_ratio;
// Equivalent min size of each IO that can reach the maximum storage speed limit:
// 512KB for oss, 4KB for hdfs
_equivalent_io_size = _is_oss ? OSS_MIN_IO_SIZE : HDFS_MIN_IO_SIZE;
if (_profile != nullptr) {
const char* random_profile = "MergedSmallIO";
ADD_TIMER(_profile, random_profile);
Expand Down Expand Up @@ -235,6 +241,9 @@ class MergeRangeFileReader : public io::FileReader {
int16 _last_box_ref = -1;
uint32 _last_box_usage = 0;
std::vector<int16> _box_ref;
bool _is_oss;
double _max_amplified_ratio;
size_t _equivalent_io_size;

Statistics _statistics;
};
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