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Optimize string sort for default collation UTF8MB4_BIN (pingcap#5375)
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ref pingcap#5294, close pingcap#5366
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@solotzg
solotzg authored Jul 21, 2022
1 parent c483f1b commit d61c1df
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Showing 8 changed files with 308 additions and 184 deletions.
166 changes: 123 additions & 43 deletions dbms/src/Columns/ColumnString.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,10 @@
#include <Columns/ColumnsCommon.h>
#include <Common/HashTable/Hash.h>
#include <DataStreams/ColumnGathererStream.h>
#include <Functions/CollationOperatorOptimized.h>
#include <fmt/core.h>


/// Used in the `reserve` method, when the number of rows is known, but sizes of elements are not.
#define APPROX_STRING_SIZE 64

Expand Down Expand Up @@ -321,54 +323,94 @@ int ColumnString::compareAtWithCollationImpl(size_t n, size_t m, const IColumn &
);
}


template <bool positive>
struct ColumnString::lessWithCollation
// Derived must implement function `int compare(const char *, size_t, const char *, size_t)`.
template <bool positive, typename Derived>
struct ColumnString::LessWithCollation
{
const ColumnString & parent;
const ICollator & collator;
const Derived & inner;

lessWithCollation(const ColumnString & parent_, const ICollator & collator_)
LessWithCollation(const ColumnString & parent_, const Derived & inner_)
: parent(parent_)
, collator(collator_)
, inner(inner_)
{}

bool operator()(size_t lhs, size_t rhs) const
FLATTEN_INLINE_PURE inline bool operator()(size_t lhs, size_t rhs) const
{
int res = collator.compare(
int res = inner.compare(
reinterpret_cast<const char *>(&parent.chars[parent.offsetAt(lhs)]),
parent.sizeAt(lhs) - 1, // Skip last zero byte.
reinterpret_cast<const char *>(&parent.chars[parent.offsetAt(rhs)]),
parent.sizeAt(rhs) - 1 // Skip last zero byte.
);

return positive ? (res < 0) : (res > 0);
if constexpr (positive)
{
return (res < 0);
}
else
{
return (res > 0);
}
}
};

void ColumnString::getPermutationWithCollationImpl(const ICollator & collator, bool reverse, size_t limit, Permutation & res) const
struct Utf8MB4BinCmp
{
size_t s = offsets.size();
res.resize(s);
for (size_t i = 0; i < s; ++i)
res[i] = i;

if (limit >= s)
limit = 0;
static FLATTEN_INLINE_PURE inline int compare(const char * s1, size_t length1, const char * s2, size_t length2)
{
return DB::BinCollatorCompare<true>(s1, length1, s2, length2);
}
};

if (limit)
// common util functions
template <>
struct ColumnString::LessWithCollation<false, void>
{
// `CollationCmpImpl` must implement function `int compare(const char *, size_t, const char *, size_t)`.
template <typename CollationCmpImpl>
static void getPermutationWithCollationImpl(const ColumnString & src, const CollationCmpImpl & collator_cmp_impl, bool reverse, size_t limit, Permutation & res)
{
if (reverse)
std::partial_sort(res.begin(), res.begin() + limit, res.end(), lessWithCollation<false>(*this, collator));
size_t s = src.offsets.size();
res.resize(s);
for (size_t i = 0; i < s; ++i)
res[i] = i;

if (limit >= s)
limit = 0;

if (limit)
{
if (reverse)
std::partial_sort(res.begin(), res.begin() + limit, res.end(), LessWithCollation<false, CollationCmpImpl>(src, collator_cmp_impl));
else
std::partial_sort(res.begin(), res.begin() + limit, res.end(), LessWithCollation<true, CollationCmpImpl>(src, collator_cmp_impl));
}
else
std::partial_sort(res.begin(), res.begin() + limit, res.end(), lessWithCollation<true>(*this, collator));
{
if (reverse)
std::sort(res.begin(), res.end(), LessWithCollation<false, CollationCmpImpl>(src, collator_cmp_impl));
else
std::sort(res.begin(), res.end(), LessWithCollation<true, CollationCmpImpl>(src, collator_cmp_impl));
}
}
else
};

void ColumnString::getPermutationWithCollationImpl(const ICollator & collator, bool reverse, size_t limit, Permutation & res) const
{
using PermutationWithCollationUtils = ColumnString::LessWithCollation<false, void>;

// optimize path for default collator `UTF8MB4_BIN`
if (TiDB::ITiDBCollator::getCollator(TiDB::ITiDBCollator::UTF8MB4_BIN) == &collator)
{
if (reverse)
std::sort(res.begin(), res.end(), lessWithCollation<false>(*this, collator));
else
std::sort(res.begin(), res.end(), lessWithCollation<true>(*this, collator));
Utf8MB4BinCmp cmp_impl;
PermutationWithCollationUtils::getPermutationWithCollationImpl(*this, cmp_impl, reverse, limit, res);
///
return;
}

{
PermutationWithCollationUtils::getPermutationWithCollationImpl(*this, collator, reverse, limit, res);
}
}

Expand All @@ -379,35 +421,73 @@ void ColumnString::updateWeakHash32(WeakHash32 & hash, const TiDB::TiDBCollatorP
if (hash.getData().size() != s)
throw Exception(fmt::format("Size of WeakHash32 does not match size of column: column size is {}, hash size is {}", s, hash.getData().size()), ErrorCodes::LOGICAL_ERROR);

const UInt8 * pos = chars.data();
UInt32 * hash_data = hash.getData().data();
Offset prev_offset = 0;

if (collator != nullptr)
{
for (const auto & offset : offsets)
if (collator->getCollatorId() == TiDB::ITiDBCollator::UTF8MB4_BIN)
{
auto str_size = offset - prev_offset;
/// Skip last zero byte.
auto sort_key = collator->sortKey(reinterpret_cast<const char *>(pos), str_size - 1, sort_key_container);
*hash_data = ::updateWeakHash32(reinterpret_cast<const UInt8 *>(sort_key.data), sort_key.size, *hash_data);

pos += str_size;
prev_offset = offset;
// Skip last zero byte.
LoopOneColumn(chars, offsets, offsets.size(), [&](const std::string_view & view, size_t) {
auto sort_key = BinCollatorSortKey<true>(view.data(), view.size());
*hash_data = ::updateWeakHash32(reinterpret_cast<const UInt8 *>(sort_key.data), sort_key.size, *hash_data);
++hash_data;
});
}
else
{
// Skip last zero byte.
LoopOneColumn(chars, offsets, offsets.size(), [&](const std::string_view & view, size_t) {
auto sort_key = collator->sortKey(view.data(), view.size(), sort_key_container);
*hash_data = ::updateWeakHash32(reinterpret_cast<const UInt8 *>(sort_key.data), sort_key.size, *hash_data);
++hash_data;
});
}
}
else
{
// Skip last zero byte.
LoopOneColumn(chars, offsets, offsets.size(), [&](const std::string_view & view, size_t) {
*hash_data = ::updateWeakHash32(reinterpret_cast<const UInt8 *>(view.data()), view.size(), *hash_data);
++hash_data;
});
}
}

void ColumnString::updateHashWithValues(IColumn::HashValues & hash_values, const TiDB::TiDBCollatorPtr & collator, String & sort_key_container) const
{
if (collator != nullptr)
{
if (collator->getCollatorId() == TiDB::ITiDBCollator::UTF8MB4_BIN)
{
// Skip last zero byte.
LoopOneColumn(chars, offsets, offsets.size(), [&hash_values](const std::string_view & view, size_t i) {
auto sort_key = BinCollatorSortKey<true>(view.data(), view.size());
size_t string_size = sort_key.size;
hash_values[i].update(reinterpret_cast<const char *>(&string_size), sizeof(string_size));
hash_values[i].update(sort_key.data, sort_key.size);
});
}
else
{
// Skip last zero byte.
LoopOneColumn(chars, offsets, offsets.size(), [&](const std::string_view & view, size_t i) {
auto sort_key = collator->sortKey(view.data(), view.size(), sort_key_container);
size_t string_size = sort_key.size;
hash_values[i].update(reinterpret_cast<const char *>(&string_size), sizeof(string_size));
hash_values[i].update(sort_key.data, sort_key.size);
});
}
}
else
{
for (const auto & offset : offsets)
for (size_t i = 0; i < offsets.size(); ++i)
{
auto str_size = offset - prev_offset;
/// Skip last zero byte.
*hash_data = ::updateWeakHash32(pos, str_size - 1, *hash_data);
size_t string_size = sizeAt(i);
size_t offset = offsetAt(i);

pos += str_size;
prev_offset = offset;
++hash_data;
hash_values[i].update(reinterpret_cast<const char *>(&string_size), sizeof(string_size));
hash_values[i].update(reinterpret_cast<const char *>(&chars[offset]), string_size);
}
}
}
Expand Down
41 changes: 7 additions & 34 deletions dbms/src/Columns/ColumnString.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,8 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>
template <bool positive>
struct less;

template <bool positive>
struct lessWithCollation;
template <bool positive, typename Derived>
struct LessWithCollation;

ColumnString() = default;

Expand Down Expand Up @@ -118,7 +118,7 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>

void insert(const Field & x) override
{
const String & s = DB::get<const String &>(x);
const auto & s = DB::get<const String &>(x);
const size_t old_size = chars.size();
const size_t size_to_append = s.size() + 1;
const size_t new_size = old_size + size_to_append;
Expand All @@ -134,7 +134,7 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>

void insertFrom(const IColumn & src_, size_t n) override
{
const ColumnString & src = static_cast<const ColumnString &>(src_);
const auto & src = static_cast<const ColumnString &>(src_);

if (n != 0)
{
Expand Down Expand Up @@ -213,7 +213,7 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>

if (collator != nullptr)
{
/// Skip last zero byte.
// Skip last zero byte.
auto sort_key = collator->sortKey(reinterpret_cast<const char *>(src), string_size - 1, sort_key_container);
string_size = sort_key.size;
src = sort_key.data;
Expand Down Expand Up @@ -259,34 +259,7 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>
}
}

void updateHashWithValues(IColumn::HashValues & hash_values, const TiDB::TiDBCollatorPtr & collator, String & sort_key_container) const override
{
if (collator != nullptr)
{
for (size_t i = 0; i < offsets.size(); ++i)
{
size_t string_size = sizeAt(i);
size_t offset = offsetAt(i);

/// Skip last zero byte.
auto sort_key = collator->sortKey(reinterpret_cast<const char *>(&chars[offset]), string_size - 1, sort_key_container);
string_size = sort_key.size;
hash_values[i].update(reinterpret_cast<const char *>(&string_size), sizeof(string_size));
hash_values[i].update(sort_key.data, sort_key.size);
}
}
else
{
for (size_t i = 0; i < offsets.size(); ++i)
{
size_t string_size = sizeAt(i);
size_t offset = offsetAt(i);

hash_values[i].update(reinterpret_cast<const char *>(&string_size), sizeof(string_size));
hash_values[i].update(reinterpret_cast<const char *>(&chars[offset]), string_size);
}
}
}
void updateHashWithValues(IColumn::HashValues & hash_values, const TiDB::TiDBCollatorPtr & collator, String & sort_key_container) const override;

void updateWeakHash32(WeakHash32 & hash, const TiDB::TiDBCollatorPtr &, String &) const override;

Expand All @@ -304,7 +277,7 @@ class ColumnString final : public COWPtrHelper<IColumn, ColumnString>

int compareAt(size_t n, size_t m, const IColumn & rhs_, int /*nan_direction_hint*/) const override
{
const ColumnString & rhs = static_cast<const ColumnString &>(rhs_);
const auto & rhs = static_cast<const ColumnString &>(rhs_);

const size_t size = sizeAt(n);
const size_t rhs_size = rhs.sizeAt(m);
Expand Down
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