diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index 00cab73..578aeb3 100644
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -130,6 +130,11 @@ int foreign_keys = 0;
int unlogged_tables = 0;
/*
+ * use log sampling (rate => 1 = 100%, 0 = don't use)
+ */
+double use_sample_rate = 0.0;
+
+/*
* tablespace selection
*/
char *tablespace = NULL;
@@ -364,6 +369,8 @@ usage(void)
" -f FILENAME read transaction script from FILENAME\n"
" -j NUM number of threads (default: 1)\n"
" -l write transaction times to log file\n"
+ " --sampling-rate NUM\n"
+ " sampling rate of the log (e.g. 0.01 for 1%% sample)\n"
" -M simple|extended|prepared\n"
" protocol for submitting queries to server (default: simple)\n"
" -n do not run VACUUM before tests\n"
@@ -877,21 +884,26 @@ top:
instr_time diff;
double usec;
- INSTR_TIME_SET_CURRENT(now);
- diff = now;
- INSTR_TIME_SUBTRACT(diff, st->txn_begin);
- usec = (double) INSTR_TIME_GET_MICROSEC(diff);
+ /* either no sampling or is within the sample */
+ if ((use_sample_rate == 0.0) || (pg_erand48(thread->random_state) <= use_sample_rate))
+ {
+
+ INSTR_TIME_SET_CURRENT(now);
+ diff = now;
+ INSTR_TIME_SUBTRACT(diff, st->txn_begin);
+ usec = (double) INSTR_TIME_GET_MICROSEC(diff);
#ifndef WIN32
- /* This is more than we really ought to know about instr_time */
- fprintf(logfile, "%d %d %.0f %d %ld %ld\n",
- st->id, st->cnt, usec, st->use_file,
- (long) now.tv_sec, (long) now.tv_usec);
+ /* This is more than we really ought to know about instr_time */
+ fprintf(logfile, "%d %d %.0f %d %ld %ld\n",
+ st->id, st->cnt, usec, st->use_file,
+ (long) now.tv_sec, (long) now.tv_usec);
#else
- /* On Windows, instr_time doesn't provide a timestamp anyway */
- fprintf(logfile, "%d %d %.0f %d 0 0\n",
- st->id, st->cnt, usec, st->use_file);
+ /* On Windows, instr_time doesn't provide a timestamp anyway */
+ fprintf(logfile, "%d %d %.0f %d 0 0\n",
+ st->id, st->cnt, usec, st->use_file);
#endif
+ }
}
if (commands[st->state]->type == SQL_COMMAND)
@@ -1918,6 +1930,7 @@ main(int argc, char **argv)
{"index-tablespace", required_argument, NULL, 3},
{"tablespace", required_argument, NULL, 2},
{"unlogged-tables", no_argument, &unlogged_tables, 1},
+ {"sampling-rate", required_argument, NULL, 4},
{NULL, 0, NULL, 0}
};
@@ -2123,6 +2136,14 @@ main(int argc, char **argv)
case 3: /* index-tablespace */
index_tablespace = optarg;
break;
+ case 4:
+ use_sample_rate = atof(optarg)/100;
+ if (use_sample_rate <= 0.0 || use_sample_rate > 1.0)
+ {
+ fprintf(stderr, "invalid sampling rate: %f\n", use_sample_rate);
+ exit(1);
+ }
+ break;
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
exit(1);
@@ -2158,6 +2179,12 @@ main(int argc, char **argv)
exit(1);
}
+ /* --sampling-rate may be used only with -l */
+ if (use_sample_rate > 0 && (! use_log)) {
+ fprintf(stderr, "log sampling rate is allowed only when logging transactions\n");
+ exit(1);
+ }
+
/*
* is_latencies only works with multiple threads in thread-based
* implementations, not fork-based ones, because it supposes that the
diff --git a/doc/src/sgml/pgbench.sgml b/doc/src/sgml/pgbench.sgml
index 437fcea..67b21aa 100644
--- a/doc/src/sgml/pgbench.sgml
+++ b/doc/src/sgml/pgbench.sgml
@@ -317,6 +317,22 @@ pgbench options> dbname>
+ rate>
+
+
+ Sampling rate, used when writing data into the log in percent. 100 means all
+ transactions will be logged, 1 means only 1% of the transactions will be logged.
+ This may also be a float, e.g. 12.5 means 12.5% will be sampled.
+
+
+ Be careful when processing the log file - e.g. when computing tps values, you
+ need to multiply the numbers accordingly (e.g. with 1% sample you'll get 1/100
+ of the actual tps).
+
+
+
+
+
querymode>