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Optimize calculation of HLL's register maximum

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Konstantin Knizhnik
2024-10-02 15:55:26 +03:00
parent a59720b5f5
commit 4a4c1b06eb
1 changed files with 4 additions and 1 deletions
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5
pgxn/neon/hll.c
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@@ -149,6 +149,8 @@ getAccessCount(const HyperLogLogRegister* reg, time_t duration)
uint32_t count = 0;
/* Simplest solution is to take in account all points fro overlapped interval */
for (size_t i = 0; i < HIST_SIZE && HIST_MIN_INTERVAL*((1 << i)/2) <= duration; i++) {
count += reg->histogram[i];
}
return count;
}
@@ -176,10 +178,11 @@ getMaximum(const HyperLogLogRegister* reg, TimestampTz since, time_t duration, d
}
if (total_count != 0)
{
const double threshold = total_count * (1 - min_hit_ratio);
for (i = 0; i < HLL_C_BITS + 1; i++)
{
// Take in account only bits with access frequncy exceeding maximal miss rate (1 - hit rate)
if (reg[i].ts >= since && 1.0 - (double)getAccessCount(&reg[i], duration) / total_count <= min_hit_ratio)
if (reg[i].ts >= since && getAccessCount(&reg[i], duration) >= threshold)
{
max = i;
}