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Add --latency-limit option to pgbench.
This allows transactions that take longer than specified limit to be counted separately. With --rate, transactions that are already late by the time we get to execute them are skipped altogether. Using --latency-limit with --rate allows you to "catch up" more quickly, if there's a hickup in the server causing a lot of transactions to stall momentarily. Fabien COELHO, reviewed by Rukh Meski and heavily refactored by me.
This commit is contained in:
Heikki Linnakangas
parent
30d7ae3c76
commit
98aed6c721
@ -140,6 +140,14 @@ double sample_rate = 0.0;
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*/
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int64 throttle_delay = 0;
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/*
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* Transactions which take longer than this limit (in usec) are counted as
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* late, and reported as such, although they are completed anyway. When
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* throttling is enabled, execution time slots that are more than this late
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* are skipped altogether, and counted separately.
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*/
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int64 latency_limit = 0;
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/*
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* tablespace selection
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*/
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@ -238,6 +246,8 @@ typedef struct
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int64 throttle_trigger; /* previous/next throttling (us) */
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int64 throttle_lag; /* total transaction lag behind throttling */
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int64 throttle_lag_max; /* max transaction lag */
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int64 throttle_latency_skipped; /* lagging transactions skipped */
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int64 latency_late; /* late transactions */
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} TState;
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#define INVALID_THREAD ((pthread_t) 0)
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@ -250,6 +260,8 @@ typedef struct
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int64 sqlats;
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int64 throttle_lag;
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int64 throttle_lag_max;
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int64 throttle_latency_skipped;
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int64 latency_late;
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} TResult;
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/*
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@ -284,6 +296,8 @@ typedef struct
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long start_time; /* when does the interval start */
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int cnt; /* number of transactions */
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int skipped; /* number of transactions skipped under
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* --rate and --latency-limit */
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double min_latency; /* min/max latencies */
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double max_latency;
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@ -348,7 +362,7 @@ static void setalarm(int seconds);
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static void *threadRun(void *arg);
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static void doLog(TState *thread, CState *st, FILE *logfile, instr_time *now,
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AggVals *agg);
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AggVals *agg, bool skipped);
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static void
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usage(void)
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@ -375,6 +389,8 @@ usage(void)
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" -f, --file=FILENAME read transaction script from FILENAME\n"
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" -j, --jobs=NUM number of threads (default: 1)\n"
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" -l, --log write transaction times to log file\n"
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" -L, --latency-limit=NUM count transactions lasting more than NUM ms\n"
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" as late.\n"
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" -M, --protocol=simple|extended|prepared\n"
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" protocol for submitting queries (default: simple)\n"
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" -n, --no-vacuum do not run VACUUM before tests\n"
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@ -994,7 +1010,9 @@ void
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agg_vals_init(AggVals *aggs, instr_time start)
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{
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/* basic counters */
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aggs->cnt = 0; /* number of transactions */
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aggs->cnt = 0; /* number of transactions (includes skipped) */
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aggs->skipped = 0; /* xacts skipped under --rate --latency-limit */
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aggs->sum_latency = 0; /* SUM(latency) */
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aggs->sum2_latency = 0; /* SUM(latency*latency) */
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@ -1050,8 +1068,34 @@ top:
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int64 wait = getPoissonRand(thread, throttle_delay);
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thread->throttle_trigger += wait;
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st->txn_scheduled = thread->throttle_trigger;
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/*
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* If this --latency-limit is used, and this slot is already late so
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* that the transaction will miss the latency limit even if it
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* completed immediately, we skip this time slot and iterate till the
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* next slot that isn't late yet.
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*/
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if (latency_limit)
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{
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int64 now_us;
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if (INSTR_TIME_IS_ZERO(now))
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INSTR_TIME_SET_CURRENT(now);
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now_us = INSTR_TIME_GET_MICROSEC(now);
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while (thread->throttle_trigger < now_us - latency_limit)
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{
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thread->throttle_latency_skipped++;
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if (logfile)
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doLog(thread, st, logfile, &now, agg, true);
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wait = getPoissonRand(thread, throttle_delay);
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thread->throttle_trigger += wait;
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st->txn_scheduled = thread->throttle_trigger;
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}
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}
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st->sleeping = 1;
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st->throttling = true;
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st->is_throttled = true;
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@ -1119,12 +1163,13 @@ top:
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if (commands[st->state + 1] == NULL)
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{
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/* only calculate latency if an option is used that needs it */
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if (progress || throttle_delay)
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if (progress || throttle_delay || latency_limit)
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{
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int64 latency;
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if (INSTR_TIME_IS_ZERO(now))
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INSTR_TIME_SET_CURRENT(now);
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latency = INSTR_TIME_GET_MICROSEC(now) - st->txn_scheduled;
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st->txn_latencies += latency;
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@ -1137,11 +1182,15 @@ top:
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* transactions, overflow would take 256 hours.
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*/
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st->txn_sqlats += latency * latency;
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/* record over the limit transactions if needed. */
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if (latency_limit && latency > latency_limit)
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thread->latency_late++;
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}
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/* record the time it took in the log */
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if (logfile)
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doLog(thread, st, logfile, &now, agg);
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doLog(thread, st, logfile, &now, agg, false);
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}
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if (commands[st->state]->type == SQL_COMMAND)
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@ -1227,7 +1276,7 @@ top:
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}
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/* Record transaction start time under logging, progress or throttling */
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if ((logfile || progress || throttle_delay) && st->state == 0)
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if ((logfile || progress || throttle_delay || latency_limit) && st->state == 0)
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{
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INSTR_TIME_SET_CURRENT(st->txn_begin);
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@ -1605,7 +1654,8 @@ top:
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* print log entry after completing one transaction.
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*/
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static void
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doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg,
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bool skipped)
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{
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double lag;
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double latency;
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@ -1622,7 +1672,10 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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INSTR_TIME_SET_CURRENT(*now);
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latency = (double) (INSTR_TIME_GET_MICROSEC(*now) - st->txn_scheduled);
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lag = (double) (INSTR_TIME_GET_MICROSEC(st->txn_begin) - st->txn_scheduled);
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if (skipped)
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lag = latency;
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else
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lag = (double) (INSTR_TIME_GET_MICROSEC(st->txn_begin) - st->txn_scheduled);
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/* should we aggregate the results or not? */
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if (agg_interval > 0)
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@ -1634,26 +1687,34 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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if (agg->start_time + agg_interval >= INSTR_TIME_GET_DOUBLE(*now))
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{
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agg->cnt += 1;
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agg->sum_latency += latency;
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agg->sum2_latency += latency * latency;
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/* first in this aggregation interval */
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if ((agg->cnt == 1) || (latency < agg->min_latency))
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agg->min_latency = latency;
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if ((agg->cnt == 1) || (latency > agg->max_latency))
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agg->max_latency = latency;
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/* and the same for schedule lag */
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if (throttle_delay)
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if (skipped)
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{
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agg->sum_lag += lag;
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agg->sum2_lag += lag * lag;
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/* there is no latency to record if the transaction was skipped */
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agg->skipped += 1;
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}
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else
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{
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agg->sum_latency += latency;
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agg->sum2_latency += latency * latency;
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if ((agg->cnt == 1) || (lag < agg->min_lag))
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agg->min_lag = lag;
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if ((agg->cnt == 1) || (lag > agg->max_lag))
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agg->max_lag = lag;
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/* first in this aggregation interval */
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if ((agg->cnt == 1) || (latency < agg->min_latency))
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agg->min_latency = latency;
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if ((agg->cnt == 1) || (latency > agg->max_latency))
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agg->max_latency = latency;
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/* and the same for schedule lag */
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if (throttle_delay)
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{
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agg->sum_lag += lag;
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agg->sum2_lag += lag * lag;
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if ((agg->cnt == 1) || (lag < agg->min_lag))
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agg->min_lag = lag;
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if ((agg->cnt == 1) || (lag > agg->max_lag))
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agg->max_lag = lag;
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}
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}
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}
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else
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@ -1677,11 +1738,15 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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agg->min_latency,
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agg->max_latency);
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if (throttle_delay)
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{
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fprintf(logfile, " %.0f %.0f %.0f %.0f",
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agg->sum_lag,
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agg->sum2_lag,
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agg->min_lag,
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agg->max_lag);
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if (latency_limit)
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fprintf(logfile, " %d", agg->skipped);
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}
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fputc('\n', logfile);
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/* move to the next inteval */
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@ -1689,6 +1754,7 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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/* reset for "no transaction" intervals */
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agg->cnt = 0;
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agg->skipped = 0;
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agg->min_latency = 0;
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agg->max_latency = 0;
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agg->sum_latency = 0;
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@ -1701,10 +1767,11 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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/* reset the values to include only the current transaction. */
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agg->cnt = 1;
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agg->skipped = skipped ? 1 : 0;
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agg->min_latency = latency;
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agg->max_latency = latency;
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agg->sum_latency = latency;
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agg->sum2_latency = latency * latency;
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agg->sum_latency = skipped ? 0.0 : latency;
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agg->sum2_latency = skipped ? 0.0 : latency * latency;
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agg->min_lag = lag;
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agg->max_lag = lag;
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agg->sum_lag = lag;
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@ -1717,14 +1784,23 @@ doLog(TState *thread, CState *st, FILE *logfile, instr_time *now, AggVals *agg)
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#ifndef WIN32
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/* This is more than we really ought to know about instr_time */
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fprintf(logfile, "%d %d %.0f %d %ld %ld",
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st->id, st->cnt, latency, st->use_file,
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(long) now->tv_sec, (long) now->tv_usec);
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if (skipped)
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fprintf(logfile, "%d %d skipped %d %ld %ld",
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st->id, st->cnt, st->use_file,
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(long) now->tv_sec, (long) now->tv_usec);
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else
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fprintf(logfile, "%d %d %.0f %d %ld %ld",
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st->id, st->cnt, latency, st->use_file,
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(long) now->tv_sec, (long) now->tv_usec);
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#else
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/* On Windows, instr_time doesn't provide a timestamp anyway */
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fprintf(logfile, "%d %d %.0f %d 0 0",
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st->id, st->cnt, latency, st->use_file);
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if (skipped)
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fprintf(logfile, "%d %d skipped %d 0 0",
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st->id, st->cnt, st->use_file);
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else
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fprintf(logfile, "%d %d %.0f %d 0 0",
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st->id, st->cnt, latency, st->use_file);
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#endif
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if (throttle_delay)
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fprintf(logfile, " %.0f", lag);
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@ -2424,7 +2500,8 @@ printResults(int ttype, int64 normal_xacts, int nclients,
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TState *threads, int nthreads,
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instr_time total_time, instr_time conn_total_time,
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int64 total_latencies, int64 total_sqlats,
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int64 throttle_lag, int64 throttle_lag_max)
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int64 throttle_lag, int64 throttle_lag_max,
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int64 throttle_latency_skipped, int64 latency_late)
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{
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double time_include,
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tps_include,
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@ -2463,7 +2540,17 @@ printResults(int ttype, int64 normal_xacts, int nclients,
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normal_xacts);
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}
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if (throttle_delay || progress)
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if (throttle_delay && latency_limit)
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printf("number of transactions skipped: " INT64_FORMAT " (%.3f %%)\n",
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throttle_latency_skipped,
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100.0 * throttle_latency_skipped / (throttle_latency_skipped + normal_xacts));
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if (latency_limit)
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printf("number of transactions above the %.1f ms latency limit: " INT64_FORMAT " (%.3f %%)\n",
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latency_limit / 1000.0, latency_late,
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100.0 * latency_late / (throttle_latency_skipped + normal_xacts));
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if (throttle_delay || progress || latency_limit)
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{
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/* compute and show latency average and standard deviation */
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double latency = 0.001 * total_latencies / normal_xacts;
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@ -2578,6 +2665,7 @@ main(int argc, char **argv)
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{"sampling-rate", required_argument, NULL, 4},
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{"aggregate-interval", required_argument, NULL, 5},
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{"rate", required_argument, NULL, 'R'},
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{"latency-limit", required_argument, NULL, 'L'},
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{NULL, 0, NULL, 0}
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};
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@ -2607,6 +2695,8 @@ main(int argc, char **argv)
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int64 total_sqlats = 0;
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int64 throttle_lag = 0;
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int64 throttle_lag_max = 0;
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int64 throttle_latency_skipped = 0;
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int64 latency_late = 0;
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int i;
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@ -2651,7 +2741,7 @@ main(int argc, char **argv)
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state = (CState *) pg_malloc(sizeof(CState));
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memset(state, 0, sizeof(CState));
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while ((c = getopt_long(argc, argv, "ih:nvp:dqSNc:j:Crs:t:T:U:lf:D:F:M:P:R:", long_options, &optindex)) != -1)
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while ((c = getopt_long(argc, argv, "ih:nvp:dqSNc:j:Crs:t:T:U:lf:D:F:M:P:R:L:", long_options, &optindex)) != -1)
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{
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switch (c)
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{
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@ -2848,6 +2938,18 @@ main(int argc, char **argv)
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throttle_delay = (int64) (1000000.0 / throttle_value);
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}
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break;
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case 'L':
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{
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double limit_ms = atof(optarg);
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if (limit_ms <= 0.0)
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{
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fprintf(stderr, "invalid latency limit: %s\n", optarg);
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exit(1);
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}
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benchmarking_option_set = true;
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latency_limit = (int64) (limit_ms * 1000);
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}
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break;
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case 0:
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/* This covers long options which take no argument. */
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if (foreign_keys || unlogged_tables)
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@ -3143,6 +3245,8 @@ main(int argc, char **argv)
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thread->random_state[0] = random();
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thread->random_state[1] = random();
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thread->random_state[2] = random();
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thread->throttle_latency_skipped = 0;
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thread->latency_late = 0;
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if (is_latencies)
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{
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@ -3217,6 +3321,8 @@ main(int argc, char **argv)
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total_latencies += r->latencies;
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total_sqlats += r->sqlats;
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throttle_lag += r->throttle_lag;
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throttle_latency_skipped += r->throttle_latency_skipped;
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latency_late += r->latency_late;
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if (r->throttle_lag_max > throttle_lag_max)
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throttle_lag_max = r->throttle_lag_max;
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INSTR_TIME_ADD(conn_total_time, r->conn_time);
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@ -3239,7 +3345,8 @@ main(int argc, char **argv)
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INSTR_TIME_SUBTRACT(total_time, start_time);
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printResults(ttype, total_xacts, nclients, threads, nthreads,
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total_time, conn_total_time, total_latencies, total_sqlats,
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throttle_lag, throttle_lag_max);
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throttle_lag, throttle_lag_max, throttle_latency_skipped,
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latency_late);
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return 0;
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}
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@ -3264,7 +3371,8 @@ threadRun(void *arg)
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int64 last_count = 0,
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last_lats = 0,
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last_sqlats = 0,
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last_lags = 0;
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last_lags = 0,
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last_skipped = 0;
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AggVals aggs;
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@ -3467,7 +3575,8 @@ threadRun(void *arg)
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/* generate and show report */
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int64 count = 0,
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lats = 0,
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sqlats = 0;
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sqlats = 0,
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skipped = 0;
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int64 lags = thread->throttle_lag;
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int64 run = now - last_report;
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double tps,
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@ -3490,23 +3599,26 @@ threadRun(void *arg)
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sqlat = 1.0 * (sqlats - last_sqlats) / (count - last_count);
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stdev = 0.001 * sqrt(sqlat - 1000000.0 * latency * latency);
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lag = 0.001 * (lags - last_lags) / (count - last_count);
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skipped = thread->throttle_latency_skipped - last_skipped;
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fprintf(stderr,
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"progress %d: %.1f s, %.1f tps, "
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"lat %.3f ms stddev %.3f",
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thread->tid, total_run, tps, latency, stdev);
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if (throttle_delay)
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||||
fprintf(stderr,
|
||||
"progress %d: %.1f s, %.1f tps, "
|
||||
"lat %.3f ms stddev %.3f, lag %.3f ms\n",
|
||||
thread->tid, total_run, tps, latency, stdev, lag);
|
||||
else
|
||||
fprintf(stderr,
|
||||
"progress %d: %.1f s, %.1f tps, "
|
||||
"lat %.3f ms stddev %.3f\n",
|
||||
thread->tid, total_run, tps, latency, stdev);
|
||||
{
|
||||
fprintf(stderr, ", lag %.3f ms", lag);
|
||||
if (latency_limit)
|
||||
fprintf(stderr, ", skipped " INT64_FORMAT, skipped);
|
||||
}
|
||||
fprintf(stderr, "\n");
|
||||
|
||||
last_count = count;
|
||||
last_lats = lats;
|
||||
last_sqlats = sqlats;
|
||||
last_lags = lags;
|
||||
last_report = now;
|
||||
last_skipped = thread->throttle_latency_skipped;
|
||||
next_report += (int64) progress *1000000;
|
||||
}
|
||||
}
|
||||
@ -3525,7 +3637,8 @@ threadRun(void *arg)
|
||||
int64 count = 0,
|
||||
lats = 0,
|
||||
sqlats = 0,
|
||||
lags = 0;
|
||||
lags = 0,
|
||||
skipped = 0;
|
||||
int64 run = now - last_report;
|
||||
double tps,
|
||||
total_run,
|
||||
@ -3550,23 +3663,26 @@ threadRun(void *arg)
|
||||
sqlat = 1.0 * (sqlats - last_sqlats) / (count - last_count);
|
||||
stdev = 0.001 * sqrt(sqlat - 1000000.0 * latency * latency);
|
||||
lag = 0.001 * (lags - last_lags) / (count - last_count);
|
||||
skipped = thread->throttle_latency_skipped - last_skipped;
|
||||
|
||||
fprintf(stderr,
|
||||
"progress: %.1f s, %.1f tps, "
|
||||
"lat %.3f ms stddev %.3f",
|
||||
total_run, tps, latency, stdev);
|
||||
if (throttle_delay)
|
||||
fprintf(stderr,
|
||||
"progress: %.1f s, %.1f tps, "
|
||||
"lat %.3f ms stddev %.3f, lag %.3f ms\n",
|
||||
total_run, tps, latency, stdev, lag);
|
||||
else
|
||||
fprintf(stderr,
|
||||
"progress: %.1f s, %.1f tps, "
|
||||
"lat %.3f ms stddev %.3f\n",
|
||||
total_run, tps, latency, stdev);
|
||||
{
|
||||
fprintf(stderr, ", lag %.3f ms", lag);
|
||||
if (latency_limit)
|
||||
fprintf(stderr, ", " INT64_FORMAT " skipped", skipped);
|
||||
}
|
||||
fprintf(stderr, "\n");
|
||||
|
||||
last_count = count;
|
||||
last_lats = lats;
|
||||
last_sqlats = sqlats;
|
||||
last_lags = lags;
|
||||
last_report = now;
|
||||
last_skipped = thread->throttle_latency_skipped;
|
||||
next_report += (int64) progress *1000000;
|
||||
}
|
||||
}
|
||||
@ -3587,6 +3703,9 @@ done:
|
||||
}
|
||||
result->throttle_lag = thread->throttle_lag;
|
||||
result->throttle_lag_max = thread->throttle_lag_max;
|
||||
result->throttle_latency_skipped = thread->throttle_latency_skipped;
|
||||
result->latency_late = thread->latency_late;
|
||||
|
||||
INSTR_TIME_SET_CURRENT(end);
|
||||
INSTR_TIME_ACCUM_DIFF(result->conn_time, end, start);
|
||||
if (logfile)
|
||||
|
||||
@ -344,6 +344,24 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><option>-L</option> <replaceable>limit</></term>
|
||||
<term><option>--latency-limit=</option><replaceable>limit</></term>
|
||||
<listitem>
|
||||
<para>
|
||||
Transaction which last more than <replaceable>limit</> milliseconds
|
||||
are counted and reported separately, as <firstterm>late</>.
|
||||
</para>
|
||||
<para>
|
||||
When throttling is used (<option>--rate=...</>), transactions that
|
||||
lag behind schedule by more than <replaceable>limit</> ms, and thus
|
||||
have no hope of meeting the latency limit, are not sent to the server
|
||||
at all. They are counted and reported separately as
|
||||
<firstterm>skipped</>.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><option>-M</option> <replaceable>querymode</></term>
|
||||
<term><option>--protocol=</option><replaceable>querymode</></term>
|
||||
@ -453,6 +471,15 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
|
||||
latency.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
If <option>--latency-limit</> is used together with <option>--rate</>,
|
||||
a transaction can lag behind so much that it is already over the
|
||||
latency limit when the previous transaction ends, because the latency
|
||||
is calculated from the scheduled start time. Such transactions are
|
||||
not sent to the server, but are skipped altogether and counted
|
||||
separately.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
A high schedule lag time is an indication that the system cannot
|
||||
process transactions at the specified rate, with the chosen number of
|
||||
@ -940,7 +967,7 @@ END;
|
||||
The format of the log is:
|
||||
|
||||
<synopsis>
|
||||
<replaceable>client_id</> <replaceable>transaction_no</> <replaceable>time</> <replaceable>file_no</> <replaceable>time_epoch</> <replaceable>time_us</> [<replaceable>schedule_lag</replaceable>]
|
||||
<replaceable>client_id</> <replaceable>transaction_no</> <replaceable>time</> <replaceable>file_no</> <replaceable>time_epoch</> <replaceable>time_us</> <optional><replaceable>schedule_lag</replaceable></optional>
|
||||
</synopsis>
|
||||
|
||||
where <replaceable>time</> is the total elapsed transaction time in microseconds,
|
||||
@ -950,20 +977,40 @@ END;
|
||||
UNIX epoch format timestamp and an offset
|
||||
in microseconds (suitable for creating an ISO 8601
|
||||
timestamp with fractional seconds) showing when
|
||||
the transaction completed. The last field, <replaceable>schedule_lag</>, is
|
||||
the difference between the transaction's scheduled start time, and the
|
||||
time it actually started, in microseconds. It is only present when the
|
||||
<option>--rate</> option is used.
|
||||
the transaction completed.
|
||||
Field <replaceable>schedule_lag</> is the difference between the
|
||||
transaction's scheduled start time, and the time it actually started, in
|
||||
microseconds. It is only present when the <option>--rate</> option is used.
|
||||
The last field <replaceable>skipped_transactions</> reports the number of
|
||||
transactions skipped because they were too far behind schedule. It is only
|
||||
present when both options <option>--rate</> and <option>--latency-limit</>
|
||||
are used.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Here are example outputs:
|
||||
Here is a snippet of the log file generated:
|
||||
<screen>
|
||||
0 199 2241 0 1175850568 995598
|
||||
0 200 2465 0 1175850568 998079
|
||||
0 201 2513 0 1175850569 608
|
||||
0 202 2038 0 1175850569 2663
|
||||
</screen></para>
|
||||
</screen>
|
||||
|
||||
Another example with --rate=100 and --latency-limit=5 (note the additional
|
||||
<replaceable>schedule_lag</> column):
|
||||
<screen>
|
||||
0 81 4621 0 1412881037 912698 3005
|
||||
0 82 6173 0 1412881037 914578 4304
|
||||
0 83 skipped 0 1412881037 914578 5217
|
||||
0 83 skipped 0 1412881037 914578 5099
|
||||
0 83 4722 0 1412881037 916203 3108
|
||||
0 84 4142 0 1412881037 918023 2333
|
||||
0 85 2465 0 1412881037 919759 740
|
||||
</screen>
|
||||
In this example, transaction 82 was late, because it's latency (6.173 ms) was
|
||||
over the 5 ms limit. The next two transactions were skipped, because they
|
||||
were already late before they were even started.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
When running a long test on hardware that can handle a lot of transactions,
|
||||
@ -979,7 +1026,7 @@ END;
|
||||
With the <option>--aggregate-interval</option> option, the logs use a bit different format:
|
||||
|
||||
<synopsis>
|
||||
<replaceable>interval_start</> <replaceable>num_of_transactions</> <replaceable>latency_sum</> <replaceable>latency_2_sum</> <replaceable>min_latency</> <replaceable>max_latency</> [<replaceable>lag_sum</> <replaceable>lag_2_sum</> <replaceable>min_lag</> <replaceable>max_lag</>]
|
||||
<replaceable>interval_start</> <replaceable>num_of_transactions</> <replaceable>latency_sum</> <replaceable>latency_2_sum</> <replaceable>min_latency</> <replaceable>max_latency</> <optional><replaceable>lag_sum</> <replaceable>lag_2_sum</> <replaceable>min_lag</> <replaceable>max_lag</> <optional><replaceable>skipped_transactions</></optional></optional>
|
||||
</synopsis>
|
||||
|
||||
where <replaceable>interval_start</> is the start of the interval (UNIX epoch
|
||||
@ -990,8 +1037,11 @@ END;
|
||||
<replaceable>latency_2_sum</> is a sum of 2nd powers of latencies. The last two
|
||||
fields are <replaceable>min_latency</> - a minimum latency within the interval, and
|
||||
<replaceable>max_latency</> - maximum latency within the interval. A transaction is
|
||||
counted into the interval when it was committed. The last four fields,
|
||||
<replaceable>lag_sum</>, <replaceable>lag_2_sum</>, <replaceable>min_lag</>, and <replaceable>max_lag</>, are only present if the --rate option is used.
|
||||
counted into the interval when it was committed. The fields in the end,
|
||||
<replaceable>lag_sum</>, <replaceable>lag_2_sum</>, <replaceable>min_lag</>,
|
||||
and <replaceable>max_lag</>, are only present if the <option>--rate</>
|
||||
option is used. The very last one, <replaceable>skipped_transactions</>,
|
||||
is only present if the option <option>--latency-limit</> is present, too.
|
||||
They are calculated from the time each transaction had to wait for the
|
||||
previous one to finish, i.e. the difference between each transaction's
|
||||
scheduled start time and the time it actually started.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user