END_TEST
START_TEST(test_union)
{
CountMinSketch *cms1 = CountMinSketchCreateWithEpsAndP(EPS, P);
CountMinSketch *cms2 = CountMinSketchCreateWithEpsAndP(EPS, P);
CountMinSketch *cms;
int num_keys = 5000;
int *keys = palloc(sizeof(int) * num_keys * 2);
int *counts = palloc0(sizeof(int) * num_keys * 2);
int i;
for (i = 0; i < num_keys; i++)
{
keys[i] = rand();
keys[num_keys + i] = rand();
}
for (i = 0; i < num_keys; i++)
{
counts[i] += rand() % 100;
counts[num_keys + i] = rand() % 100;
CountMinSketchAdd(cms1, &keys[i], sizeof(int), counts[i]);
CountMinSketchAdd(cms2, &keys[num_keys + i], sizeof(int), counts[num_keys + i]);
}
cms = CountMinSketchMerge(cms1, cms2);
for (i = 0; i < num_keys * 2; i++)
{
float diff = CountMinSketchEstimateFrequency(cms, &keys[i], sizeof(int)) - counts[i];
ck_assert(diff / cms->count < EPS);
}
}
END_TEST
START_TEST(test_false_positives)
{
CountMinSketch *cms = CountMinSketchCreateWithEpsAndP(EPS, P);
int range = 1 << 20;
int num_keys = 1 << 16;
int *counts = palloc0(sizeof(int) * range);
int *keys = palloc(sizeof(int) * num_keys);
int i;
float num_errors = 0;
for (i = 0; i < num_keys; i++)
keys[i] = rand() % range;
for (i = 0; i < num_keys; i++)
{
int c = rand() % 100;
counts[keys[i]] += c;
CountMinSketchAdd(cms, &keys[i], sizeof(int), c);
}
for (i = 0; i < range; i++)
{
float diff = 1.0 * abs(CountMinSketchEstimateFrequency(cms, &i, sizeof(int)) - counts[i]);
if (diff / cms->count > EPS)
num_errors++;
}
pfree(counts);
pfree(keys);
ck_assert(num_errors / range < (1 - P));
}
static CountMinSketch *
cmsketch_create(float8 eps, float8 p)
{
if (p <= 0 || p >= 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("p must be in [0, 1]")));
if (eps <= 0 || eps >= 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("eps must be in [0, 1]")));
return CountMinSketchCreateWithEpsAndP(eps, p);
}
CountMinSketch *
CountMinSketchCreate(void)
{
return CountMinSketchCreateWithEpsAndP(DEFAULT_EPS, DEFAULT_P);
}