Provide pgbench --show-script to dump built-in scripts.

Author: Fabien Coelho
Reviewed-by: Ibrar Ahmed
Discussion: https://postgr.es/m/alpine.DEB.2.21.1904081737390.5867%40lancre

doc/src/sgml/ref/pgbench.sgml

@@ -355,7 +355,6 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
       </listitem>
      </varlistentry>
 
-
      <varlistentry>
       <term><option>-c</option> <replaceable>clients</replaceable></term>
       <term><option>--client=</option><replaceable>clients</replaceable></term>
@@ -617,6 +616,16 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>--show-script</option><replaceable>scriptname</replaceable></term>
+      <listitem>
+       <para>
+        Show the actual code of builtin script <replaceable>scriptname</replaceable>
+        on stderr, and exit immediately.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>-t</option> <replaceable>transactions</replaceable></term>
       <term><option>--transactions=</option><replaceable>transactions</replaceable></term>

src/bin/pgbench/pgbench.c

@@ -651,6 +651,7 @@ usage(void)
 		   "  --progress-timestamp     use Unix epoch timestamps for progress\n"
 		   "  --random-seed=SEED       set random seed (\"time\", \"rand\", integer)\n"
 		   "  --sampling-rate=NUM      fraction of transactions to log (e.g., 0.01 for 1%%)\n"
+		   "  --show-script=NAME       show builtin script code, then exit\n"
 		   "\nCommon options:\n"
 		   "  -d, --debug              print debugging output\n"
 		   "  -h, --host=HOSTNAME      database server host or socket directory\n"
@@ -4684,7 +4685,7 @@ listAvailableScripts(void)
 
 	fprintf(stderr, "Available builtin scripts:\n");
 	for (i = 0; i < lengthof(builtin_script); i++)
-		fprintf(stderr, "\t%s\n", builtin_script[i].name);
+		fprintf(stderr, "  %13s: %s\n", builtin_script[i].name, builtin_script[i].desc);
 	fprintf(stderr, "\n");
 }
 
@@ -5124,6 +5125,7 @@ main(int argc, char **argv)
 		{"log-prefix", required_argument, NULL, 7},
 		{"foreign-keys", no_argument, NULL, 8},
 		{"random-seed", required_argument, NULL, 9},
+		{"show-script", required_argument, NULL, 10},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -5476,6 +5478,14 @@ main(int argc, char **argv)
 					exit(1);
 				}
 				break;
+			case 10:			/* list */
+				{
+					const BuiltinScript *s = findBuiltin(optarg);
+
+					fprintf(stderr, "-- %s: %s\n%s\n", s->name, s->desc, s->script);
+					exit(0);
+				}
+				break;
 			default:
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);

src/bin/pgbench/t/002_pgbench_no_server.pl

@@ -218,6 +218,15 @@ pgbench(
 	],
 	'pgbench builtin list');
 
+# builtin listing
+pgbench(
+	'--show-script se',
+	0,
+	[qr{^$}],
+	[ qr{select-only: }, qr{SELECT abalance FROM pgbench_accounts WHERE},
+	  qr{(?!UPDATE)}, qr{(?!INSERT)} ],
+	'pgbench builtin listing');
+
 my @script_tests = (
 
 	# name, err, { file => contents }