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PG-172: Exponential histogram for time buckets.

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This commit is contained in:
Ibrar Ahmed
2021-02-02 15:30:28 +00:00
parent 8fea207cbf
commit 12ba1e39d1
4 changed files with 121 additions and 39 deletions
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83
pg_stat_monitor.c
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@@ -54,6 +54,7 @@ static struct rusage rusage_start;
static struct rusage rusage_end;
static unsigned char *pgss_qbuf[MAX_BUCKETS];
static int get_histogram_bucket(double q_time);
static bool IsSystemInitialized(void);
static void dump_queries_buffer(int bucket_id, unsigned char *buf, int buf_len);
static double time_diff(struct timeval end, struct timeval start);
@@ -77,11 +78,12 @@ PG_FUNCTION_INFO_V1(pg_stat_monitor_1_2);
PG_FUNCTION_INFO_V1(pg_stat_monitor_1_3);
PG_FUNCTION_INFO_V1(pg_stat_monitor);
PG_FUNCTION_INFO_V1(pg_stat_monitor_settings);
PG_FUNCTION_INFO_V1(get_histogram_timings);
static uint pg_get_client_addr(void);
static int pg_get_application_name(char* application_name);
static PgBackendStatus *pg_get_backend_status(void);
static Datum textarray_get_datum(char arr[][CMD_LEN], int len);
static Datum textarray_get_datum(char arr[][1024], int len, int str_len);
static Datum intarray_get_datum(int32 arr[], int len);
#if PG_VERSION_NUM >= 130000
@@ -949,16 +951,8 @@ static void pgss_store(uint64 queryId,
/* increment only in case of PGSS_EXEC */
if (kind == PGSS_EXEC)
{
for (i = 0; i < MAX_RESPONSE_BUCKET; i++)
{
if (total_time < PGSM_RESPOSE_TIME_LOWER_BOUND + (PGSM_RESPOSE_TIME_STEP * i))
{
e->counters.resp_calls[i]++;
break;
}
}
if (total_time > PGSM_RESPOSE_TIME_LOWER_BOUND + (PGSM_RESPOSE_TIME_STEP * MAX_RESPONSE_BUCKET))
e->counters.resp_calls[MAX_RESPONSE_BUCKET - 1]++;
int index = get_histogram_bucket(total_time);
e->counters.resp_calls[index]++;
}
_snprintf(e->counters.info.application_name, application_name, application_name_len, APPLICATIONNAME_LEN);
@@ -1209,7 +1203,7 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo,
else
values[i++] = IntArrayGetTextDatum(tmp.info.relations, len);
values[i++] = TextArrayGetTextDatum(tmp.info.cmd_type, CMD_LST);
values[i++] = TextArrayGetTextDatum((char (*)[1024])tmp.info.cmd_type, CMD_LST, CMD_LEN);
values[i++] = Int64GetDatumFast(tmp.error.elevel);
if (strlen(tmp.error.sqlcode) <= 0)
values[i++] = CStringGetTextDatum("0");
@@ -2213,9 +2207,10 @@ comp_location(const void *a, const void *b)
else
return 0;
}
/* Convert array into Text dataum */
static Datum
textarray_get_datum(char arr[][CMD_LEN], int len)
textarray_get_datum(char arr[][1024], int len, int str_len)
{
int j;
char str[1024];
@@ -2226,15 +2221,15 @@ textarray_get_datum(char arr[][CMD_LEN], int len)
/* Need to calculate the actual size, and avoid unnessary memory usage */
for (j = 0; j < len; j++)
{
if (strlen(arr[j]) <= 0)
if (arr[j] == NULL || strlen(arr[j]) <= 0)
continue;
if (first)
{
snprintf(str, CMD_LEN, "%s", arr[j]);
snprintf(str, str_len, "%s", arr[j]);
first = false;
continue;
}
snprintf(str, CMD_LEN, "%s,%s", str, arr[j]);
snprintf(str, str_len, "%s,%s", str, arr[j]);
}
return CStringGetTextDatum(str);
@@ -2665,3 +2660,59 @@ unpack_sql_state(int sql_state)
return buf;
}
static int
get_histogram_bucket(double q_time)
{
double q_min = PGSM_HISTOGRAM_MIN;
double q_max = PGSM_HISTOGRAM_MAX;
int b_count = PGSM_HISTOGRAM_BUCKETS;
int index = 0;
double b_max;
double b_min;
double bucket_size;
q_time -= q_min;
b_max = log(q_max - q_min);
b_min = 0;
bucket_size = (b_max - b_min) / (double)b_count;
for(index = 1; index <= b_count; index++)
{
double b_start = (index == 1)? 0 : exp(bucket_size * (index - 1));
double b_end = exp(bucket_size * index);
if( (index == 1 && q_time < b_start)
|| (q_time >= b_start && q_time <= b_end)
|| (index == b_count && q_time > b_end) )
{
return index - 1;
}
}
return 0;
}
Datum
get_histogram_timings(PG_FUNCTION_ARGS)
{
double q_min = PGSM_HISTOGRAM_MIN;
double q_max = PGSM_HISTOGRAM_MAX;
int b_count = PGSM_HISTOGRAM_BUCKETS;
int index = 0;
double b_max;
double b_min;
double bucket_size;
char range[50][1024] = {0};
b_max = log(q_max - q_min);
b_min = 0;
bucket_size = (b_max - b_min) / (double)b_count;
for(index = 1; index <= b_count; index++)
{
int64 b_start = (index == 1)? 0 : exp(bucket_size * (index - 1));
int64 b_end = exp(bucket_size * index);
sprintf(range[index-1], "(%d - %d)}", b_start, b_end);
}
return TextArrayGetTextDatum(range, b_count, 1024);
}