Thank you for your grate documentation and fix working!!!
It becomes very helpful for understanding our feature.
Hopefully it will help make it, or part of it, pass through.
I add two feature in gauss_B_4.patch.
1) Add gaussianProbability() function
It is same as exponentialProbability(). And the feature is as same as
before.
Ok, that is better for readability and easy reuse.
2) Add result of max/min percent of the range
It is almost same as --exponential option's result. However, max percent of
the range is center of distribution
and min percent of the range is most side of distribution.
Here is the output example,
Ok, good that make it homogeneous with the exponential case.
+ pgbench_account's aid selected with a truncated gaussian distribution
+ standard deviation threshold: 5.0
+ decile percents: 0.0% 0.1% 2.1% 13.6% 34.1% 34.1% 13.6% 2.1% 0.1% 0.0%
+ probability of max/min percent of the range: 4.0% 0.0%
And I add the explanation about this in the document.
This is a definite improvement. I tested these minor changes and
everything seems ok.
Attached is a very small update. One word removed from the doc, and one
redundant declaration removed from the code.
I also have a problem with assert Assert. I finally figured out that
Assert is not compiled in by default, thus it is generally ignored. So it
is more for debugging purposes when activated than for guarding against
some unexpected user errors.
--
Fabien.diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index e07206a..0247a05 100644
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -41,6 +41,7 @@
#include math.h
#include signal.h
#include sys/time.h
+#include assert.h
#ifdef HAVE_SYS_SELECT_H
#include sys/select.h
#endif
@@ -173,6 +174,11 @@ bool is_connect; /* establish connection for each transaction */
bool is_latencies; /* report per-command latencies */
int main_pid; /* main process id used in log filename */
+/* gaussian/exponential distribution tests */
+double threshold; /* threshold for gaussian or exponential */
+booluse_gaussian = false;
+bool use_exponential = false;
+
char *pghost = ;
char *pgport = ;
char *login = NULL;
@@ -294,11 +300,11 @@ static int num_commands = 0; /* total number of Command structs */
static int debug = 0; /* debug flag */
/* default scenario */
-static char *tpc_b = {
+static char *tpc_b_fmt = {
\\set nbranches CppAsString2(nbranches) * :scale\n
\\set ntellers CppAsString2(ntellers) * :scale\n
\\set naccounts CppAsString2(naccounts) * :scale\n
- \\setrandom aid 1 :naccounts\n
+ \\setrandom aid 1 :naccounts%s\n
\\setrandom bid 1 :nbranches\n
\\setrandom tid 1 :ntellers\n
\\setrandom delta -5000 5000\n
@@ -312,11 +318,11 @@ static char *tpc_b = {
};
/* -N case */
-static char *simple_update = {
+static char *simple_update_fmt = {
\\set nbranches CppAsString2(nbranches) * :scale\n
\\set ntellers CppAsString2(ntellers) * :scale\n
\\set naccounts CppAsString2(naccounts) * :scale\n
- \\setrandom aid 1 :naccounts\n
+ \\setrandom aid 1 :naccounts%s\n
\\setrandom bid 1 :nbranches\n
\\setrandom tid 1 :ntellers\n
\\setrandom delta -5000 5000\n
@@ -328,9 +334,9 @@ static char *simple_update = {
};
/* -S case */
-static char *select_only = {
+static char *select_only_fmt = {
\\set naccounts CppAsString2(naccounts) * :scale\n
- \\setrandom aid 1 :naccounts\n
+ \\setrandom aid 1 :naccounts%s\n
SELECT abalance FROM pgbench_accounts WHERE aid = :aid;\n
};
@@ -377,6 +383,8 @@ usage(void)
-v, --vacuum-all vacuum all four standard tables before tests\n
--aggregate-interval=NUM aggregate data over NUM seconds\n
--sampling-rate=NUM fraction of transactions to log (e.g. 0.01 for 1%%)\n
+ --exponential=NUMexponential distribution with NUM threshold parameter\n
+ --gaussian=NUM gaussian distribution with NUM threshold parameter\n
\nCommon options:\n
-d, --debug print debugging output\n
-h, --host=HOSTNAME database server host or socket directory\n
@@ -2329,6 +2337,30 @@ process_builtin(char *tb)
return my_commands;
}
+/*
+ * compute the probability of the truncated gaussian random generation
+ * to draw values in the i-th slot of the range.
+ */
+static double gaussianProbability(int i, int slots, double threshold)
+{
+ assert(1 = i i = slots);
+ return (0.50 * (erf (threshold * (1.0 - 1.0 / slots * (2.0 * i - 2.0)) / sqrt(2.0)) -
+ erf (threshold * (1.0 - 1.0 / slots * 2.0 * i) / sqrt(2.0))) /
+ erf (threshold / sqrt(2.0)));
+}
+
+/*
+ * compute the probability of the truncated exponential random generation
+ * to draw values in the i-th slot of the range.
+ */
+static double exponentialProbability(int i, int slots, double threshold)
+{
+ assert(1 = i i = slots);
+ return (exp(- threshold * (i - 1) / slots) - exp(- threshold * i / slots)) /
+
