diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index b03d0cc50f..8d9b642fdd 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -170,7 +170,7 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
         <replaceable>init_steps</replaceable> specifies the
         initialization steps to be performed, using one character per step.
         Each step is invoked in the specified order.
-        The default is <literal>dtgvp</literal>.
+        The default is <literal>dt(g)vp</literal>.
         The available steps are:
 
         <variablelist>
@@ -226,6 +226,22 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
            </para>
           </listitem>
          </varlistentry>
+         <varlistentry>
+          <term><literal>(</literal> (Begin)</term>
+          <listitem>
+           <para>
+            Begin a transaction.
+           </para>
+          </listitem>
+         </varlistentry>
+         <varlistentry>
+          <term><literal>)</literal> (Commit)</term>
+          <listitem>
+           <para>
+            Commit a transaction.
+           </para>
+          </listitem>
+         </varlistentry>
          <varlistentry>
           <term><literal>v</literal> (Vacuum)</term>
           <listitem>
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 3057665bbe..f77e33056c 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -132,8 +132,8 @@ static int	pthread_join(pthread_t th, void **thread_return);
 /********************************************************************
  * some configurable parameters */
 
-#define DEFAULT_INIT_STEPS "dtgvp"	/* default -I setting */
-#define ALL_INIT_STEPS "dtgGvpf"	/* all possible steps */
+#define DEFAULT_INIT_STEPS "dt(g)vp"	/* default -I setting */
+#define ALL_INIT_STEPS "dtgGvpf()"	/* all possible steps */
 
 #define LOG_STEP_SECONDS	5	/* seconds between log messages */
 #define DEFAULT_NXACTS	10		/* default nxacts */
@@ -3823,12 +3823,6 @@ initGenerateDataClientSide(PGconn *con)
 
 	fprintf(stderr, "generating data (client-side)...\n");
 
-	/*
-	 * we do all of this in one transaction to enable the backend's
-	 * data-loading optimizations
-	 */
-	executeStatement(con, "begin");
-
 	/* truncate away any old data */
 	initTruncateTables(con);
 
@@ -3940,8 +3934,6 @@ initGenerateDataClientSide(PGconn *con)
 	}
 
 	termPQExpBuffer(&sql);
-
-	executeStatement(con, "commit");
 }
 
 /*
@@ -3958,12 +3950,6 @@ initGenerateDataServerSide(PGconn *con)
 
 	fprintf(stderr, "generating data (server-side)...\n");
 
-	/*
-	 * we do all of this in one transaction to enable the backend's
-	 * data-loading optimizations
-	 */
-	executeStatement(con, "begin");
-
 	/* truncate away any old data */
 	initTruncateTables(con);
 
@@ -3989,8 +3975,6 @@ initGenerateDataServerSide(PGconn *con)
 	executeStatement(con, sql.data);
 
 	termPQExpBuffer(&sql);
-
-	executeStatement(con, "commit");
 }
 
 /*
@@ -4076,6 +4060,8 @@ initCreateFKeys(PGconn *con)
 static void
 checkInitSteps(const char *initialize_steps)
 {
+	bool in_tx = false;
+
 	if (initialize_steps[0] == '\0')
 	{
 		pg_log_fatal("no initialization steps specified");
@@ -4090,6 +4076,36 @@ checkInitSteps(const char *initialize_steps)
 			pg_log_info("Allowed step characters are: \"" ALL_INIT_STEPS "\".");
 			exit(1);
 		}
+
+		if (*step == '(')
+		{
+			if (in_tx)
+			{
+				pg_log_fatal("opening a transaction inside a transaction");
+				exit(1);
+			}
+			in_tx = true;
+		}
+		else if (*step == ')')
+		{
+			if (!in_tx)
+			{
+				pg_log_fatal("closing a transaction without opening it");
+				exit(1);
+			}
+			in_tx = false;
+		}
+		else if (*step == 'v' && in_tx)
+		{
+			pg_log_fatal("cannot run vacuum within a transaction");
+			exit(1);
+		}
+	}
+
+	if (in_tx)
+	{
+		pg_log_fatal("uncommitted transaction");
+		exit(1);
 	}
 }
 
@@ -4150,6 +4166,14 @@ runInitSteps(const char *initialize_steps)
 				op = "foreign keys";
 				initCreateFKeys(con);
 				break;
+			case '(':
+				op = "begin";
+				executeStatement(con, "begin");
+				break;
+			case ')':
+				op = "commit";
+				executeStatement(con, "commit");
+				break;
 			case ' ':
 				break;			/* ignore */
 			default:
diff --git a/src/bin/pgbench/t/002_pgbench_no_server.pl b/src/bin/pgbench/t/002_pgbench_no_server.pl
index e38c7d77d1..11c677ae54 100644
--- a/src/bin/pgbench/t/002_pgbench_no_server.pl
+++ b/src/bin/pgbench/t/002_pgbench_no_server.pl
@@ -139,6 +139,8 @@ my @options = (
 		'--progress-timestamp => --progress', '--progress-timestamp',
 		[qr{allowed only under}]
 	],
+
+	# initialization
 	[
 		'-I without init option',
 		'-I dtg',
@@ -152,6 +154,26 @@ my @options = (
 			qr{Allowed step characters are}
 		]
 	],
+	[
+		'bad init tx 1',
+		'-i -I )',
+		[	qr{open} ]
+	],
+	[
+		'bad init tx 2',
+		'-i -I (',
+		[	qr{uncommit} ]
+	],
+	[
+		'bad init tx 3',
+		'-i -I (v)',
+		[	qr{vacuum} ]
+	],
+	[
+		'bad init tx 4',
+		'-i -I ((',
+		[	qr{inside} ]
+	],
 	[
 		'bad random seed',
 		'--random-seed=one',