Hello Alvaro,

Thanks for having a look at this patch.

Think of one initialization followed by two appends:

  SELECT 1 AS x \cset
  SELECT 2 \; SELECT 3 AS y \cset
  SELECT 4 \; SELECT 5 \; SELECT 6 AS z \gset

In the end, we must have the full 6 queries

  "SELECT 1 AS x \; SELECT 2 \; SELECT 3 AS y \; SELECT 4 \; SELECT 5 \; SELECT 6 AS 
z"

and know that we want to set variables from queries 1, 3 and 6 and ignore
the 3 others.

I'm not sure I understand this.  Why is the "SELECT 2" ignored?

Because there is no \cset nor \gset attached to it, so the command does not say to put the result into variables.

(I can see why the 4 and 5 are ignored: they are not processed by gset).

Same thing with SELECT 2, which is followed by "\;", meaning execute and that's all.

What exactly does \cset do?  I thought "SELECT 2 \; SELECT 3 AS y \cset"
would search for the \; and process *both* queries.

No, "\cset" does not end the compound query, only ";" or "\gset" do that.

\cset separates queries (like \;) and adds the fact that the just preceding query result is to be put into variables when received.

  \cset = \; + store result into variables

  \gset = ; + store result into variables

From a performance point of view, the point is to be able to use compound
queries which reduce the number of round trips so should impact latency.

I think the doc addition should be split.

Indeed, as the current version is confusing.

Attached an attempt at clarifying the documentation on this point. The doc is split as suggested, descriptions and examples are specific to each presented case.

--
Fabien.
diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index b5e3a62a33..246944ea79 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -954,6 +954,87 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
   </para>
 
   <variablelist>
+   <varlistentry id='pgbench-metacommand-cset'>
+    <term>
+     <literal>\cset [<replaceable>prefix</replaceable>]</literal>
+    </term>
+
+    <listitem>
+     <para>
+      This command may be used to end SQL queries, replacing an embedded
+      semicolon (<literal>\;</literal>) within a compound SQL command.
+     </para>
+
+     <para>
+      When this command is used, the preceding SQL query is expected to
+      return one row, the columns of which are stored into variables named after
+      column names, and prefixed with <replaceable>prefix</replaceable> if provided.
+     </para>
+
+     <para>
+      The following example sends three queries as one compound SQL command,
+      inducing one message sent at the protocol level.
+      The result of the second query is stored into variable <replaceable>two</replaceable>,
+      whereas the results of the other queries are discarded.
+<programlisting>
+-- compound of 3 queries
+SELECT 1 AS one \; SELECT 2 AS two \cset
+SELECT 2;
+</programlisting>
+     </para>
+
+     <note>
+      <para>
+        <literal>\cset</literal> does not work when empty SQL queries appear
+        within a compound SQL command.
+      </para>
+     </note>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry id='pgbench-metacommand-gset'>
+    <term>
+     <literal>\gset [<replaceable>prefix</replaceable>]</literal>
+    </term>
+
+    <listitem>
+     <para>
+      This commands may be used to end SQL queries, replacing a final semicolon
+      (<literal>;</literal>). 
+     </para>
+
+     <para>
+      When this command is used, the preceding SQL query is expected to
+      return one row, the columns of which are stored into variables named after
+      column names, and prefixed with <replaceable>prefix</replaceable> if provided.
+     </para>
+
+     <para>
+      The following example puts the final account balance from the first query
+      into variable <replaceable>abalance</replaceable>, and fills variables
+      <replaceable>p_two</replaceable> and <replaceable>p_three</replaceable> 
+      with integers from the last query.
+      The result of the second query is discarded.
+<programlisting>
+UPDATE pgbench_accounts
+  SET abalance = abalance + :delta
+  WHERE aid = :aid
+  RETURNING abalance \gset
+-- compound of two queries
+SELECT 1 \;
+SELECT 2 AS two, 3 AS three \gset p_
+</programlisting>
+     </para>
+
+     <note>
+      <para>
+        <literal>\gset</literal> does not work when empty SQL queries appear
+        within a compound SQL command.
+      </para>
+     </note>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>\if</literal> <replaceable class="parameter">expression</replaceable></term>
     <term><literal>\elif</literal> <replaceable class="parameter">expression</replaceable></term>
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 73d3de0677..f1e84860b4 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -490,12 +490,15 @@ static const char *QUERYMODE[] = {"simple", "extended", "prepared"};
 
 typedef struct
 {
-	char	   *line;			/* text of command line */
+	char	   *first_line;		/* first line for short display */
+	char	   *lines;			/* full multi-line text of command */
 	int			command_num;	/* unique index of this Command struct */
 	int			type;			/* command type (SQL_COMMAND or META_COMMAND) */
 	MetaCommand meta;			/* meta command identifier, or META_NONE */
 	int			argc;			/* number of command words */
 	char	   *argv[MAX_ARGS]; /* command word list */
+	int			compound;       /* last compound command (number of \;) */
+	char	  **gset;           /* per-compound command prefix */
 	PgBenchExpr *expr;			/* parsed expression, if needed */
 	SimpleStats stats;			/* time spent in this command */
 } Command;
@@ -1718,6 +1721,107 @@ valueTruth(PgBenchValue *pval)
 	}
 }
 
+/* read all responses from backend, storing into variable or discarding */
+static bool
+read_response(CState *st, char **gset)
+{
+	PGresult   *res;
+	int			compound = 0;
+
+	while ((res = PQgetResult(st->con)) != NULL)
+	{
+		switch (PQresultStatus(res))
+		{
+			case PGRES_COMMAND_OK: /* non-SELECT commands */
+			case PGRES_EMPTY_QUERY: /* may be used for testing no-op overhead */
+				if (gset[compound] != NULL)
+				{
+					fprintf(stderr,
+							"client %d file %d command %d compound %d: "
+							"\\gset/cset expects a row\n",
+							st->id, st->use_file, st->command, compound);
+					st->ecnt++;
+					return false;
+				}
+				break; /* OK */
+
+			case PGRES_TUPLES_OK:
+				if (gset[compound] != NULL)
+				{
+					/* store result into variables if required */
+					int ntuples = PQntuples(res),
+						nfields = PQnfields(res),
+						f;
+
+					if (ntuples != 1)
+					{
+						fprintf(stderr,
+								"client %d file %d command %d compound %d: "
+								"expecting one row, got %d\n",
+								st->id, st->use_file, st->command, compound, ntuples);
+						st->ecnt++;
+						PQclear(res);
+						discard_response(st);
+						return false;
+					}
+
+					for (f = 0; f < nfields ; f++)
+					{
+						char *varname = PQfname(res, f);
+						/* prefix varname if required, will be freed below */
+						if (*gset[compound] != '\0')
+							varname = psprintf("%s%s", gset[compound], varname);
+
+						/* store result as a string */
+						if (!putVariable(st, "gset", varname,
+										 PQgetvalue(res, 0, f)))
+						{
+							/* internal error, should it rather abort? */
+							fprintf(stderr,
+									"client %d file %d command %d compound %d: "
+									"error storing into var %s\n",
+									st->id, st->use_file, st->command, compound,
+									varname);
+							st->ecnt++;
+							PQclear(res);
+							discard_response(st);
+							return false;
+						}
+
+						/* free varname only if allocated because of prefix */
+						if (*gset[compound] != '\0')
+							free(varname);
+					}
+				}
+				/* otherwise the result is simply thrown away by PQclear below */
+				break;	/* OK */
+
+			default:
+				/* everything else is unexpected, so probably an error */
+				fprintf(stderr,
+						"client %d file %d aborted in command %d compound %d: %s",
+						st->id, st->use_file, st->command, compound,
+						PQerrorMessage(st->con));
+				st->ecnt++;
+				PQclear(res);
+				discard_response(st);
+				return false;
+		}
+
+		PQclear(res);
+		compound += 1;
+	}
+
+	if (compound == 0)
+	{
+		fprintf(stderr, "client %d command %d: no results\n", st->id, st->command);
+		st->ecnt++;
+		return false;
+	}
+
+	return true;
+}
+
 /* get a value as an int, tell if there is a problem */
 static bool
 coerceToInt(PgBenchValue *pval, int64 *ival)
@@ -2825,7 +2929,6 @@ evaluateSleep(CState *st, int argc, char **argv, int *usecs)
 static void
 doCustom(TState *thread, CState *st, StatsData *agg)
 {
-	PGresult   *res;
 	Command    *command;
 	instr_time	now;
 	bool		end_tx_processed = false;
@@ -3319,26 +3422,12 @@ doCustom(TState *thread, CState *st, StatsData *agg)
 				if (PQisBusy(st->con))
 					return;		/* don't have the whole result yet */
 
-				/*
-				 * Read and discard the query result;
-				 */
-				res = PQgetResult(st->con);
-				switch (PQresultStatus(res))
-				{
-					case PGRES_COMMAND_OK:
-					case PGRES_TUPLES_OK:
-					case PGRES_EMPTY_QUERY:
-						/* OK */
-						PQclear(res);
-						discard_response(st);
-						st->state = CSTATE_END_COMMAND;
-						break;
-					default:
-						commandFailed(st, "SQL", PQerrorMessage(st->con));
-						PQclear(res);
-						st->state = CSTATE_ABORTED;
-						break;
-				}
+				/* read, store or discard the query results */
+				if (read_response(st, command->gset))
+					st->state = CSTATE_END_COMMAND;
+				else
+					st->state = CSTATE_ABORTED;
+
 				break;
 
 				/*
@@ -3993,7 +4082,7 @@ runInitSteps(const char *initialize_steps)
 
 /*
  * Replace :param with $n throughout the command's SQL text, which
- * is a modifiable string in cmd->argv[0].
+ * is a modifiable string in cmd->lines.
  */
 static bool
 parseQuery(Command *cmd)
@@ -4001,8 +4090,7 @@ parseQuery(Command *cmd)
 	char	   *sql,
 			   *p;
 
-	/* We don't want to scribble on cmd->argv[0] until done */
-	sql = pg_strdup(cmd->argv[0]);
+	sql = pg_strdup(cmd->lines);
 
 	cmd->argc = 1;
 
@@ -4026,7 +4114,7 @@ parseQuery(Command *cmd)
 		if (cmd->argc >= MAX_ARGS)
 		{
 			fprintf(stderr, "statement has too many arguments (maximum is %d): %s\n",
-					MAX_ARGS - 1, cmd->argv[0]);
+					MAX_ARGS - 1, cmd->lines);
 			pg_free(name);
 			return false;
 		}
@@ -4038,7 +4126,7 @@ parseQuery(Command *cmd)
 		cmd->argc++;
 	}
 
-	pg_free(cmd->argv[0]);
+	Assert(cmd->argv[0] == NULL);
 	cmd->argv[0] = sql;
 	return true;
 }
@@ -4097,22 +4185,10 @@ syntax_error(const char *source, int lineno,
 	exit(1);
 }
 
-/*
- * Parse a SQL command; return a Command struct, or NULL if it's a comment
- *
- * On entry, psqlscan.l has collected the command into "buf", so we don't
- * really need to do much here except check for comment and set up a
- * Command struct.
- */
-static Command *
-process_sql_command(PQExpBuffer buf, const char *source)
+static char *
+skip_sql_comments(char *p)
 {
-	Command    *my_command;
-	char	   *p;
-	char	   *nlpos;
-
 	/* Skip any leading whitespace, as well as "--" style comments */
-	p = buf->data;
 	for (;;)
 	{
 		if (isspace((unsigned char) *p))
@@ -4132,35 +4208,111 @@ process_sql_command(PQExpBuffer buf, const char *source)
 	if (*p == '\0')
 		return NULL;
 
+	return p;
+}
+
+/*
+ * Parse a SQL command; return a Command struct, or NULL if it's a comment
+ *
+ * On entry, psqlscan.l has collected the command into "buf", so we don't
+ * really need to do much here except check for comment and set up a
+ * Command struct.
+ */
+static Command *
+create_sql_command(PQExpBuffer buf, const char *source, int compounds)
+{
+	Command    *my_command;
+	char	   *p = skip_sql_comments(buf->data);
+
+	if (p == NULL)
+		return NULL;
+
 	/* Allocate and initialize Command structure */
 	my_command = (Command *) pg_malloc0(sizeof(Command));
 	my_command->command_num = num_commands++;
 	my_command->type = SQL_COMMAND;
 	my_command->meta = META_NONE;
+	my_command->argc = 0;
+	my_command->compound = compounds;
+	my_command->gset = pg_malloc0(sizeof(char *) * (compounds+1));
 	initSimpleStats(&my_command->stats);
 
-	/*
-	 * Install query text as the sole argv string.  If we are using a
-	 * non-simple query mode, we'll extract parameters from it later.
-	 */
-	my_command->argv[0] = pg_strdup(p);
-	my_command->argc = 1;
+	my_command->lines = pg_strdup(p);
+
+	return my_command;
+}
+
+/*
+ * append "more" text to current compound command which may have been
+ * interrupted by \cset.
+ */
+static void
+append_sql_command(Command *my_command, char *more, int compounds)
+{
+	size_t	lmore;
+	size_t	len = strlen(my_command->lines);
+	int		nc;
+
+	Assert(my_command->type == SQL_COMMAND && len > 0);
+
+	more = skip_sql_comments(more);
+
+	if (more == NULL)
+		return;
+
+	/* append command text, embedding a ';' in place of the \cset */
+	lmore = strlen(more);
+	my_command->lines = pg_realloc(my_command->lines, len + lmore + 2);
+	my_command->lines[len] = ';';
+	memcpy(my_command->lines + len + 1, more, lmore + 1);
+
+	/* update number of compounds and extend array of prefixes */
+	nc = my_command->compound + 1 + compounds;
+	my_command->gset =
+		pg_realloc(my_command->gset, sizeof(char *) * (nc+1));
+	memset(my_command->gset + my_command->compound + 1, 0,
+		   sizeof(char *) * (compounds + 1));
+	my_command->compound = nc;
+}
+
+static void
+postprocess_sql_command(Command *my_command)
+{
+	char	   *nlpos;
+	char	   *p;
+
+	Assert(my_command->type == SQL_COMMAND);
 
 	/*
 	 * If SQL command is multi-line, we only want to save the first line as
-	 * the "line" label.
+	 * the "line" label for display.
 	 */
+	p = my_command->lines;
 	nlpos = strchr(p, '\n');
 	if (nlpos)
 	{
-		my_command->line = pg_malloc(nlpos - p + 1);
-		memcpy(my_command->line, p, nlpos - p);
-		my_command->line[nlpos - p] = '\0';
+		my_command->first_line = pg_malloc(nlpos - p + 1);
+		memcpy(my_command->first_line, p, nlpos - p);
+		my_command->first_line[nlpos - p] = '\0';
 	}
 	else
-		my_command->line = pg_strdup(p);
+		my_command->first_line = pg_strdup(p);
 
-	return my_command;
+	/* parse query if necessary */
+	switch (querymode)
+	{
+		case QUERY_SIMPLE:
+			my_command->argv[0] = my_command->lines;
+			my_command->argc++;
+			break;
+		case QUERY_EXTENDED:
+		case QUERY_PREPARED:
+			if (!parseQuery(my_command))
+				exit(1);
+			break;
+		default:
+			exit(1);
+	}
 }
 
 /*
@@ -4218,7 +4370,7 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 		if (my_command->meta == META_SET)
 		{
 			if (!expr_lex_one_word(sstate, &word_buf, &word_offset))
-				syntax_error(source, lineno, my_command->line, my_command->argv[0],
+				syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 							 "missing argument", NULL, -1);
 
 			offsets[j] = word_offset;
@@ -4239,10 +4391,11 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 		my_command->expr = expr_parse_result;
 
 		/* Save line, trimming any trailing newline */
-		my_command->line = expr_scanner_get_substring(sstate,
-													  start_offset,
-													  expr_scanner_offset(sstate),
-													  true);
+		my_command->first_line =
+			expr_scanner_get_substring(sstate,
+									   start_offset,
+									   expr_scanner_offset(sstate),
+									   true);
 
 		expr_scanner_finish(yyscanner);
 
@@ -4255,7 +4408,7 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 	while (expr_lex_one_word(sstate, &word_buf, &word_offset))
 	{
 		if (j >= MAX_ARGS)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "too many arguments", NULL, -1);
 
 		offsets[j] = word_offset;
@@ -4264,19 +4417,20 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 	}
 
 	/* Save line, trimming any trailing newline */
-	my_command->line = expr_scanner_get_substring(sstate,
-												  start_offset,
-												  expr_scanner_offset(sstate),
-												  true);
+	my_command->first_line =
+		expr_scanner_get_substring(sstate,
+								   start_offset,
+								   expr_scanner_offset(sstate),
+								   true);
 
 	if (my_command->meta == META_SLEEP)
 	{
 		if (my_command->argc < 2)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "missing argument", NULL, -1);
 
 		if (my_command->argc > 3)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "too many arguments", NULL,
 						 offsets[3] - start_offset);
 
@@ -4305,7 +4459,7 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 			if (pg_strcasecmp(my_command->argv[2], "us") != 0 &&
 				pg_strcasecmp(my_command->argv[2], "ms") != 0 &&
 				pg_strcasecmp(my_command->argv[2], "s") != 0)
-				syntax_error(source, lineno, my_command->line, my_command->argv[0],
+				syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 							 "unrecognized time unit, must be us, ms or s",
 							 my_command->argv[2], offsets[2] - start_offset);
 		}
@@ -4313,25 +4467,32 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 	else if (my_command->meta == META_SETSHELL)
 	{
 		if (my_command->argc < 3)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "missing argument", NULL, -1);
 	}
 	else if (my_command->meta == META_SHELL)
 	{
 		if (my_command->argc < 2)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "missing command", NULL, -1);
 	}
 	else if (my_command->meta == META_ELSE || my_command->meta == META_ENDIF)
 	{
 		if (my_command->argc != 1)
-			syntax_error(source, lineno, my_command->line, my_command->argv[0],
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "unexpected argument", NULL, -1);
 	}
+	else if (pg_strcasecmp(my_command->argv[0], "gset") == 0 ||
+			 pg_strcasecmp(my_command->argv[0], "cset") == 0)
+	{
+		if (my_command->argc > 2)
+			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
+						 "at most one argument expected", NULL, -1);
+	}
 	else
 	{
 		/* my_command->meta == META_NONE */
-		syntax_error(source, lineno, my_command->line, my_command->argv[0],
+		syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 					 "invalid command", NULL, -1);
 	}
 
@@ -4410,6 +4571,9 @@ ParseScript(const char *script, const char *desc, int weight)
 	PQExpBufferData line_buf;
 	int			alloc_num;
 	int			index;
+	bool		is_compound = false;
+	int			lineno;
+	int			start_offset;
 
 #define COMMANDS_ALLOC_NUM 128
 	alloc_num = COMMANDS_ALLOC_NUM;
@@ -4433,6 +4597,7 @@ ParseScript(const char *script, const char *desc, int weight)
 	 * stdstrings should be true, which is a bit riskier.
 	 */
 	psql_scan_setup(sstate, script, strlen(script), 0, true);
+	start_offset = expr_scanner_offset(sstate) - 1;
 
 	initPQExpBuffer(&line_buf);
 
@@ -4442,31 +4607,28 @@ ParseScript(const char *script, const char *desc, int weight)
 	{
 		PsqlScanResult sr;
 		promptStatus_t prompt;
-		Command    *command;
+		Command    *command = NULL;
 
 		resetPQExpBuffer(&line_buf);
+		lineno = expr_scanner_get_lineno(sstate, start_offset);
+
+		sstate->semicolons = 0;
 
 		sr = psql_scan(sstate, &line_buf, &prompt);
 
-		/* If we collected a SQL command, process that */
-		command = process_sql_command(&line_buf, desc);
-		if (command)
+		if (is_compound)
 		{
-			ps.commands[index] = command;
-			index++;
-
-			if (index >= alloc_num)
-			{
-				alloc_num += COMMANDS_ALLOC_NUM;
-				ps.commands = (Command **)
-					pg_realloc(ps.commands, sizeof(Command *) * alloc_num);
-			}
+			/* a multi-line command ended with \cset */
+			append_sql_command(ps.commands[index-1], line_buf.data,
+							   sstate->semicolons);
+			is_compound = false;
 		}
-
-		/* If we reached a backslash, process that */
-		if (sr == PSCAN_BACKSLASH)
+		else
 		{
-			command = process_backslash_command(sstate, desc);
+			/* If we collected a new SQL command, process that */
+			command = create_sql_command(&line_buf, desc, sstate->semicolons);
+
+			/* store new command */
 			if (command)
 			{
 				ps.commands[index] = command;
@@ -4481,6 +4643,67 @@ ParseScript(const char *script, const char *desc, int weight)
 			}
 		}
 
+		if (sr == PSCAN_BACKSLASH)
+		{
+			command = process_backslash_command(sstate, desc);
+
+			if (command)
+			{
+				char * bs_cmd = command->argv[0];
+
+				/* merge gset variants into preceeding SQL command */
+				if (pg_strcasecmp(bs_cmd, "gset") == 0 ||
+					pg_strcasecmp(bs_cmd, "cset") == 0)
+				{
+					int		cindex;
+					Command *sql_cmd;
+
+					is_compound = bs_cmd[0] == 'c';
+
+					if (index == 0)
+						syntax_error(desc, lineno, NULL, NULL,
+									 "\\gset/cset cannot start a script",
+									 NULL, -1);
+
+					sql_cmd = ps.commands[index-1];
+
+					if (sql_cmd->type != SQL_COMMAND)
+						syntax_error(desc, lineno, NULL, NULL,
+									 "\\gset/cset must follow a SQL command",
+									 sql_cmd->first_line, -1);
+
+					/* this \gset applies to the last sub-command */
+					cindex = sql_cmd->compound;
+
+					if (sql_cmd->gset[cindex] != NULL)
+						syntax_error(desc, lineno, NULL, NULL,
+									 "\\gset/cset cannot follow one another",
+									 NULL, -1);
+
+					/* get variable prefix */
+					if (command->argc <= 1 || command->argv[1][0] == '\0')
+						sql_cmd->gset[cindex] = "";
+					else
+						sql_cmd->gset[cindex] = command->argv[1];
+
+					/* cleanup unused backslash command */
+					pg_free(command);
+				}
+				else /* any other backslash command is a Command */
+				{
+					ps.commands[index] = command;
+					index++;
+
+					if (index >= alloc_num)
+					{
+						alloc_num += COMMANDS_ALLOC_NUM;
+						ps.commands = (Command **)
+							pg_realloc(ps.commands, sizeof(Command *) * alloc_num);
+					}
+				}
+			}
+		}
+
 		/* Done if we reached EOF */
 		if (sr == PSCAN_INCOMPLETE || sr == PSCAN_EOL)
 			break;
@@ -4836,7 +5059,7 @@ printResults(TState *threads, StatsData *total, instr_time total_time,
 					printf("   %11.3f  %s\n",
 						   (cstats->count > 0) ?
 						   1000.0 * cstats->sum / cstats->count : 0.0,
-						   (*commands)->line);
+						   (*commands)->first_line);
 				}
 			}
 		}
@@ -5307,28 +5530,19 @@ main(int argc, char **argv)
 		internal_script_used = true;
 	}
 
-	/* if not simple query mode, parse the script(s) to find parameters */
-	if (querymode != QUERY_SIMPLE)
-	{
-		for (i = 0; i < num_scripts; i++)
-		{
-			Command   **commands = sql_script[i].commands;
-			int			j;
-
-			for (j = 0; commands[j] != NULL; j++)
-			{
-				if (commands[j]->type != SQL_COMMAND)
-					continue;
-				if (!parseQuery(commands[j]))
-					exit(1);
-			}
-		}
-	}
-
-	/* compute total_weight */
+	/* complete SQL command initializations and collect total weight */
 	for (i = 0; i < num_scripts; i++)
+	{
+		Command   **commands = sql_script[i].commands;
+		int			j;
+
+		for (j = 0; commands[j] != NULL; j++)
+			if (commands[j]->type == SQL_COMMAND)
+				postprocess_sql_command(commands[j]);
+
 		/* cannot overflow: weight is 32b, total_weight 64b */
 		total_weight += sql_script[i].weight;
+	}
 
 	if (total_weight == 0 && !is_init_mode)
 	{
diff --git a/src/bin/pgbench/pgbench.h b/src/bin/pgbench/pgbench.h
index de50340434..f4a7327dc7 100644
--- a/src/bin/pgbench/pgbench.h
+++ b/src/bin/pgbench/pgbench.h
@@ -11,6 +11,7 @@
 #ifndef PGBENCH_H
 #define PGBENCH_H
 
+#include "fe_utils/psqlscan_int.h"
 #include "fe_utils/psqlscan.h"
 
 /*
diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index 0081989026..79ec6fb6f5 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -530,6 +530,48 @@ pgbench(
 }
 	});
 
+# working \gset and \cset
+pgbench(
+	'-t 1', 0,
+	[ qr{type: .*/001_pgbench_gset_and_cset}, qr{processed: 1/1} ],
+	[   qr{command=3.: int 0\b},
+		qr{command=5.: int 1\b},
+		qr{command=6.: int 2\b},
+		qr{command=8.: int 3\b},
+		qr{command=9.: int 4\b},
+		qr{command=10.: int 5\b},
+		qr{command=12.: int 6\b},
+		qr{command=13.: int 7\b},
+		qr{command=14.: int 8\b},
+		qr{command=16.: int 9\b} ],
+	'pgbench gset and cset commands',
+	{   '001_pgbench_gset_and_cset' => q{-- test gset and cset
+-- no columns
+SELECT \gset
+-- one value
+SELECT 0 AS i0 \gset
+\set i debug(:i0)
+-- two values
+SELECT 1 AS i1, 2 AS i2 \gset
+\set i debug(:i1)
+\set i debug(:i2)
+-- cset & gset to follow
+SELECT :i2 + 1 AS i3, :i2 * :i2 AS i4 \cset
+  SELECT 5 AS i5 \gset
+\set i debug(:i3)
+\set i debug(:i4)
+\set i debug(:i5)
+-- with prefix
+SELECT 6 AS i6, 7 AS i7 \cset x_
+  SELECT 8 AS i8 \gset y_
+\set i debug(:x_i6)
+\set i debug(:x_i7)
+\set i debug(:y_i8)
+-- overwrite existing variable
+SELECT 0 AS i9, 9 AS i9 \gset
+\set i debug(:i9)
+} });
+
 # trigger many expression errors
 my @errors = (
 
@@ -737,21 +779,45 @@ SELECT LEAST(:i, :i, :i, :i, :i, :i, :i, :i, :i, :i, :i);
 		[qr{invalid command .* "nosuchcommand"}], q{\nosuchcommand}
 	],
 	[ 'misc empty script', 1, [qr{empty command list for script}], q{} ],
-	[
-		'bad boolean',                     2,
-		[qr{malformed variable.*trueXXX}], q{\set b :badtrue or true}
-	],);
+	[   'bad boolean',                     2,
+		[qr{malformed variable.*trueXXX}], q{\set b :badtrue or true} ],
 
+	# GSET & CSET
+	[   'gset no row',                    2,
+		[qr{expecting one row, got 0\b}], q{SELECT WHERE FALSE \gset} ],
+	[   'cset no row',                    2,
+		[qr{expecting one row, got 0\b}], q{SELECT WHERE FALSE \cset
+SELECT 1 AS i\gset}, 1 ],
+	[ 'gset alone', 1, [qr{gset/cset cannot start a script}], q{\gset} ],
+	[   'gset no SQL',                        1,
+		[qr{gset/cset must follow a SQL command}], q{\set i +1
+\gset} ],
+	[   'gset too many args',                        1,
+		[qr{at most one argument expected}], q{SELECT 1 \gset a b} ],
+	[   'gset after gset',                        1,
+	    [qr{gset/cset cannot follow one another}], q{SELECT 1 AS i \gset
+\gset} ],
+	[   'gset non SELECT', 2,
+		[qr{gset/cset expects a row}],
+		q{DROP TABLE IF EXISTS no_such_table \gset} ],
+	[   'gset bad default name', 2,
+		[qr{error storing into var \?column\?}],
+		q{SELECT 1 \gset} ],
+	[   'gset bad name', 2,
+		[qr{error storing into var bad name!}],
+		q{SELECT 1 AS "bad name!" \gset} ],
+	);
 
 for my $e (@errors)
 {
-	my ($name, $status, $re, $script) = @$e;
+	my ($name, $status, $re, $script, $no_prepare) = @$e;
 	$status != 0 or die "invalid expected status for test \"$name\"";
 	my $n = '001_pgbench_error_' . $name;
 	$n =~ s/ /_/g;
 	pgbench(
-		'-n -t 1 -M prepared -Dfoo=bla -Dnull=null -Dtrue=true -Done=1 -Dzero=0.0 ' .
-		'-Dbadtrue=trueXXX -Dmaxint=9223372036854775807 -Dminint=-9223372036854775808',
+		'-n -t 1 -Dfoo=bla -Dnull=null -Dtrue=true -Done=1 -Dzero=0.0 -Dbadtrue=trueXXX' .
+		' -Dmaxint=9223372036854775807 -Dminint=-9223372036854775808' .
+			($no_prepare ? '' : ' -M prepared'),
 		$status,
 		[ $status == 1 ? qr{^$} : qr{processed: 0/1} ],
 		$re,
diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
index 02d95498e4..d9ac285d1e 100644
--- a/src/fe_utils/psqlscan.l
+++ b/src/fe_utils/psqlscan.l
@@ -693,8 +693,15 @@ other			.
 	 * substitution.  We want these before {self}, also.
 	 */
 
-"\\"[;:]		{
-					/* Force a semicolon or colon into the query buffer */
+"\\";			{
+					/* Count compound commands */
+					cur_state->semicolons++;
+					/* Force a semicolon into the query buffer */
+					psqlscan_emit(cur_state, yytext + 1, 1);
+				}
+
+"\\":			{
+					/* Force a colon into the query buffer */
 					psqlscan_emit(cur_state, yytext + 1, 1);
 				}
 
diff --git a/src/include/fe_utils/psqlscan_int.h b/src/include/fe_utils/psqlscan_int.h
index 0be0db69ab..8ef4abd92d 100644
--- a/src/include/fe_utils/psqlscan_int.h
+++ b/src/include/fe_utils/psqlscan_int.h
@@ -112,6 +112,7 @@ typedef struct PsqlScanStateData
 	int			start_state;	/* yylex's starting/finishing state */
 	int			paren_depth;	/* depth of nesting in parentheses */
 	int			xcdepth;		/* depth of nesting in slash-star comments */
+	int			semicolons;		/* number of embedded (\;) semi-colons */
 	char	   *dolqstart;		/* current $foo$ quote start string */
 
 	/*

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