database/mariadb-columnstore-engine
1
0
Fork 0
mirror of https://github.com/mariadb-corporation/mariadb-columnstore-engine.git synced 2025-07-30 19:23:07 +03:00
Code Activity

MCOL-5199 This patch solves the overal performance degradation introduced with a new way of char columns hashing

Browse Source 
in aggregation code
The patch disables padding that forces hasher to calculate over the whole 2k buffer. This patch also moves hashing code
into the common place where it belongs.
This commit is contained in:
Roman Nozdrin
2022-08-16 20:04:09 +00:00
parent 20f57b713a
commit 72e264e8ef
5 changed files with 126 additions and 88 deletions
Download Patch File Download Diff File Expand all files Collapse all files

77
utils/common/hasher.h
View File

@ -26,8 +26,10 @@
#pragma once
#include <cstddef>
#include <stdint.h>
#include <string.h>
#include <string>
#include "mcs_basic_types.h"
namespace utils
@ -203,6 +205,81 @@ class Hasher_r
}
};
// This stream hasher was borrowed from RobinHood
class Hasher64_r
{
public:
inline uint64_t operator()(const void* ptr, uint32_t len, uint64_t x = 0ULL)
{
auto const* const data64 = static_cast<uint64_t const*>(ptr);
uint64_t h = seed ^ (len * m);
std::size_t const n_blocks = len / 8;
if (x)
{
x *= m;
x ^= x >> r;
x *= m;
h ^= x;
h *= m;
}
for (std::size_t i = 0; i < n_blocks; ++i)
{
uint64_t k;
memcpy(&k, data64 + i, sizeof(k));
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
}
auto const* const data8 = reinterpret_cast<uint8_t const*>(data64 + n_blocks);
switch (len & 7U)
{
case 7:
h ^= static_cast<uint64_t>(data8[6]) << 48U;
// FALLTHROUGH
case 6:
h ^= static_cast<uint64_t>(data8[5]) << 40U;
// FALLTHROUGH
case 5:
h ^= static_cast<uint64_t>(data8[4]) << 32U;
// FALLTHROUGH
case 4:
h ^= static_cast<uint64_t>(data8[3]) << 24U;
// FALLTHROUGH
case 3:
h ^= static_cast<uint64_t>(data8[2]) << 16U;
// FALLTHROUGH
case 2:
h ^= static_cast<uint64_t>(data8[1]) << 8U;
// FALLTHROUGH
case 1:
h ^= static_cast<uint64_t>(data8[0]);
h *= m;
// FALLTHROUGH
default: break;
}
return h;
}
inline uint64_t finalize(uint64_t h, uint64_t len) const
{
h ^= h >> r;
h *= m;
h ^= h >> r;
return h;
}
private:
static constexpr uint64_t m = 0xc6a4a7935bd1e995ULL;
static constexpr uint64_t seed = 0xe17a1465ULL;
static constexpr unsigned int r = 47;
};
class Hasher128
{
public: