Here is a review & updated version of the patch.
Patch applies and compiles without problem on current head,
and worked for the various tests I made with custom scripts.
This patch is a good thing, and I recommand warmly its inclusion. It
extends greatly pgbench custom capabilities by allowing arbitrary integer
expressions, and will allow to add other functions (I'll send abs() & a
hash(), and possibly others).
I'm not sure about what Makefile changes could be necessary for
various environments, it looks ok to me as it is.
I have included the following additional changes in v2:
(1) small update to pgbench documentation. English proof reading is welcome.
(2) improve error reporting to display the file and line from where an error
is raised, and also the column on syntax errors (yyline is always 1...).
The prior status was that there were no way to get this information, which
was quite annoying. It could probably be improved further.
(3) spacing fixed in a few places.
If Robert is ok with these changes, I think it could be applied.
--
Fabien.diff --git a/contrib/pgbench/.gitignore b/contrib/pgbench/.gitignore
index 489a2d6..aae819e 100644
--- a/contrib/pgbench/.gitignore
+++ b/contrib/pgbench/.gitignore
@@ -1 +1,3 @@
+/exprparse.c
+/exprscan.c
/pgbench
diff --git a/contrib/pgbench/Makefile b/contrib/pgbench/Makefile
index b8e2fc8..67e2bf6 100644
--- a/contrib/pgbench/Makefile
+++ b/contrib/pgbench/Makefile
@@ -4,7 +4,7 @@ PGFILEDESC = "pgbench - a simple program for running benchmark tests"
PGAPPICON = win32
PROGRAM = pgbench
-OBJS = pgbench.o $(WIN32RES)
+OBJS = pgbench.o exprparse.o $(WIN32RES)
PG_CPPFLAGS = -I$(libpq_srcdir)
PG_LIBS = $(libpq_pgport) $(PTHREAD_LIBS)
@@ -18,8 +18,22 @@ subdir = contrib/pgbench
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
+
+distprep: exprparse.c exprscan.c
endif
ifneq ($(PORTNAME), win32)
override CFLAGS += $(PTHREAD_CFLAGS)
endif
+
+# There is no correct way to write a rule that generates two files.
+# Rules with two targets don't have that meaning, they are merely
+# shorthand for two otherwise separate rules. To be safe for parallel
+# make, we must chain the dependencies like this. The semicolon is
+# important, otherwise make will choose the built-in rule for
+# gram.y=>gram.c.
+
+exprparse.h: exprparse.c ;
+
+# exprscan is compiled as part of exprparse
+exprparse.o: exprscan.c
diff --git a/contrib/pgbench/exprparse.y b/contrib/pgbench/exprparse.y
new file mode 100644
index 0000000..243c6b9
--- /dev/null
+++ b/contrib/pgbench/exprparse.y
@@ -0,0 +1,96 @@
+%{
+/*-------------------------------------------------------------------------
+ *
+ * exprparse.y
+ * bison grammar for a simple expression syntax
+ *
+ * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include "pgbench.h"
+
+PgBenchExpr *expr_parse_result;
+
+static PgBenchExpr *make_integer_constant(int64 ival);
+static PgBenchExpr *make_variable(char *varname);
+static PgBenchExpr *make_op(char operator, PgBenchExpr *lexpr,
+ PgBenchExpr *rexpr);
+
+%}
+
+%expect 0
+%name-prefix="expr_yy"
+
+%union
+{
+ int64 ival;
+ char *str;
+ PgBenchExpr *expr;
+}
+
+%type <expr> expr
+%type <ival> INTEGER
+%type <str> VARIABLE
+%token INTEGER VARIABLE
+%token CHAR_ERROR /* never used, will raise a syntax error */
+
+%left '+' '-'
+%left '*' '/' '%'
+%right UMINUS
+
+%%
+
+result: expr { expr_parse_result = $1; }
+
+expr: '(' expr ')' { $$ = $2; }
+ | '+' expr %prec UMINUS { $$ = $2; }
+ | '-' expr %prec UMINUS { $$ = make_op('-', make_integer_constant(0), $2); }
+ | expr '+' expr { $$ = make_op('+', $1, $3); }
+ | expr '-' expr { $$ = make_op('-', $1, $3); }
+ | expr '*' expr { $$ = make_op('*', $1, $3); }
+ | expr '/' expr { $$ = make_op('/', $1, $3); }
+ | expr '%' expr { $$ = make_op('%', $1, $3); }
+ | INTEGER { $$ = make_integer_constant($1); }
+ | VARIABLE { $$ = make_variable($1); }
+ ;
+
+%%
+
+static PgBenchExpr *
+make_integer_constant(int64 ival)
+{
+ PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
+
+ expr->etype = ENODE_INTEGER_CONSTANT;
+ expr->u.integer_constant.ival = ival;
+ return expr;
+}
+
+static PgBenchExpr *
+make_variable(char *varname)
+{
+ PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
+
+ expr->etype = ENODE_VARIABLE;
+ expr->u.variable.varname = varname;
+ return expr;
+}
+
+static PgBenchExpr *
+make_op(char operator, PgBenchExpr *lexpr, PgBenchExpr *rexpr)
+{
+ PgBenchExpr *expr = pg_malloc(sizeof(PgBenchExpr));
+
+ expr->etype = ENODE_OPERATOR;
+ expr->u.operator.operator = operator;
+ expr->u.operator.lexpr = lexpr;
+ expr->u.operator.rexpr = rexpr;
+ return expr;
+}
+
+#include "exprscan.c"
diff --git a/contrib/pgbench/exprscan.l b/contrib/pgbench/exprscan.l
new file mode 100644
index 0000000..4c9229c
--- /dev/null
+++ b/contrib/pgbench/exprscan.l
@@ -0,0 +1,105 @@
+%{
+/*-------------------------------------------------------------------------
+ *
+ * exprscan.l
+ * a lexical scanner for a simple expression syntax
+ *
+ * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/* line and column number for error reporting */
+static int yyline = 0, yycol = 0;
+
+/* Handles to the buffer that the lexer uses internally */
+static YY_BUFFER_STATE scanbufhandle;
+static char *scanbuf;
+static int scanbuflen;
+
+/* flex 2.5.4 doesn't bother with a decl for this */
+int expr_yylex(void);
+
+%}
+
+%option 8bit
+%option never-interactive
+%option nodefault
+%option noinput
+%option nounput
+%option noyywrap
+%option warn
+%option prefix="expr_yy"
+
+non_newline [^\n\r]
+space [ \t\r\f]
+
+%%
+
+"+" { yycol += yyleng; return '+'; }
+"-" { yycol += yyleng; return '-'; }
+"*" { yycol += yyleng; return '*'; }
+"/" { yycol += yyleng; return '/'; }
+"%" { yycol += yyleng; return '%'; }
+"(" { yycol += yyleng; return '('; }
+")" { yycol += yyleng; return ')'; }
+:[a-zA-Z0-9_]+ { yycol += yyleng; yylval.str = pg_strdup(yytext + 1); return VARIABLE; }
+[0-9]+ { yycol += yyleng; yylval.ival = strtoint64(yytext); return INTEGER; }
+
+[\n] { yycol = 0; yyline++; }
+{space} { yycol += yyleng; /* ignore */ }
+
+. {
+ yycol += yyleng;
+ fprintf(stderr, "unexpected character '%s'\n", yytext);
+ return CHAR_ERROR;
+ }
+%%
+
+void
+yyerror(const char *message)
+{
+ /* yyline is always 1 as pgbench calls the parser for each line...
+ * so the interesting location information is the column number */
+ fprintf(stderr, "%s at column %d\n", message, yycol);
+ /* go on to raise the error from pgbench with more information */
+ /* exit(1); */
+}
+
+/*
+ * Called before any actual parsing is done
+ */
+void
+expr_scanner_init(const char *str)
+{
+ Size slen = strlen(str);
+
+ /*
+ * Might be left over after error
+ */
+ if (YY_CURRENT_BUFFER)
+ yy_delete_buffer(YY_CURRENT_BUFFER);
+
+ /*
+ * Make a scan buffer with special termination needed by flex.
+ */
+ scanbuflen = slen;
+ scanbuf = pg_malloc(slen + 2);
+ memcpy(scanbuf, str, slen);
+ scanbuf[slen] = scanbuf[slen + 1] = YY_END_OF_BUFFER_CHAR;
+ scanbufhandle = yy_scan_buffer(scanbuf, slen + 2);
+
+ BEGIN(INITIAL);
+}
+
+
+/*
+ * Called after parsing is done to clean up after seg_scanner_init()
+ */
+void
+expr_scanner_finish(void)
+{
+ yy_delete_buffer(scanbufhandle);
+ pg_free(scanbuf);
+}
diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index 2761d1d6..06dc1c1 100644
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -57,6 +57,8 @@
#define M_PI 3.14159265358979323846
#endif
+#include "pgbench.h"
+
/*
* Multi-platform pthread implementations
*/
@@ -289,6 +291,7 @@ typedef struct
int type; /* command type (SQL_COMMAND or META_COMMAND) */
int argc; /* number of command words */
char *argv[MAX_ARGS]; /* command word list */
+ PgBenchExpr *expr; /* parsed expression */
} Command;
typedef struct
@@ -423,7 +426,7 @@ usage(void)
* This function is a modified version of scanint8() from
* src/backend/utils/adt/int8.c.
*/
-static int64
+int64
strtoint64(const char *str)
{
const char *ptr = str;
@@ -879,6 +882,85 @@ getQueryParams(CState *st, const Command *command, const char **params)
params[i] = getVariable(st, command->argv[i + 1]);
}
+static bool
+evaluateExpr(CState *st, PgBenchExpr *expr, int64 *retval)
+{
+ switch (expr->etype)
+ {
+ case ENODE_INTEGER_CONSTANT:
+ {
+ *retval = expr->u.integer_constant.ival;
+ return false;
+ }
+
+ case ENODE_VARIABLE:
+ {
+ char *var;
+
+ if ((var = getVariable(st, expr->u.variable.varname)) == NULL)
+ {
+ fprintf(stderr, "undefined variable %s\n",
+ expr->u.variable.varname);
+ return true;
+ }
+ *retval = strtoint64(var);
+ return false;
+ }
+
+ case ENODE_OPERATOR:
+ {
+ int64 lval;
+ int64 rval;
+
+ if (evaluateExpr(st, expr->u.operator.lexpr, &lval))
+ return true;
+ if (evaluateExpr(st, expr->u.operator.rexpr, &rval))
+ return true;
+ switch (expr->u.operator.operator)
+ {
+ case '+':
+ *retval = lval + rval;
+ return false;
+
+ case '-':
+ *retval = lval - rval;
+ return false;
+
+ case '*':
+ *retval = lval * rval;
+ return false;
+
+ case '/':
+ if (rval == 0)
+ {
+ fprintf(stderr, "division by zero\n");
+ return true;
+ }
+ *retval = lval / rval;
+ return false;
+
+ case '%':
+ if (rval == 0)
+ {
+ fprintf(stderr, "division by zero\n");
+ return true;
+ }
+ *retval = lval % rval;
+ return false;
+ }
+
+ fprintf(stderr, "bad operator\n");
+ return true;
+ }
+
+ default:
+ break;
+ }
+
+ fprintf(stderr, "bad expression\n");
+ return true;
+}
+
/*
* Run a shell command. The result is assigned to the variable if not NULL.
* Return true if succeeded, or false on error.
@@ -1515,64 +1597,16 @@ top:
}
else if (pg_strcasecmp(argv[0], "set") == 0)
{
- char *var;
- int64 ope1,
- ope2;
char res[64];
+ PgBenchExpr *expr = commands[st->state]->expr;
+ int64 result;
- if (*argv[2] == ':')
+ if (evaluateExpr(st, expr, &result))
{
- if ((var = getVariable(st, argv[2] + 1)) == NULL)
- {
- fprintf(stderr, "%s: undefined variable %s\n", argv[0], argv[2]);
- st->ecnt++;
- return true;
- }
- ope1 = strtoint64(var);
- }
- else
- ope1 = strtoint64(argv[2]);
-
- if (argc < 5)
- snprintf(res, sizeof(res), INT64_FORMAT, ope1);
- else
- {
- if (*argv[4] == ':')
- {
- if ((var = getVariable(st, argv[4] + 1)) == NULL)
- {
- fprintf(stderr, "%s: undefined variable %s\n", argv[0], argv[4]);
- st->ecnt++;
- return true;
- }
- ope2 = strtoint64(var);
- }
- else
- ope2 = strtoint64(argv[4]);
-
- if (strcmp(argv[3], "+") == 0)
- snprintf(res, sizeof(res), INT64_FORMAT, ope1 + ope2);
- else if (strcmp(argv[3], "-") == 0)
- snprintf(res, sizeof(res), INT64_FORMAT, ope1 - ope2);
- else if (strcmp(argv[3], "*") == 0)
- snprintf(res, sizeof(res), INT64_FORMAT, ope1 * ope2);
- else if (strcmp(argv[3], "/") == 0)
- {
- if (ope2 == 0)
- {
- fprintf(stderr, "%s: division by zero\n", argv[0]);
- st->ecnt++;
- return true;
- }
- snprintf(res, sizeof(res), INT64_FORMAT, ope1 / ope2);
- }
- else
- {
- fprintf(stderr, "%s: unsupported operator %s\n", argv[0], argv[3]);
- st->ecnt++;
- return true;
- }
+ st->ecnt++;
+ return true;
}
+ sprintf(res, INT64_FORMAT, result);
if (!putVariable(st, argv[0], argv[1], res))
{
@@ -2151,7 +2185,7 @@ parseQuery(Command *cmd, const char *raw_sql)
/* Parse a command; return a Command struct, or NULL if it's a comment */
static Command *
-process_commands(char *buf)
+process_commands(char *buf, const char * source, const int lineno)
{
const char delim[] = " \f\n\r\t\v";
@@ -2180,18 +2214,38 @@ process_commands(char *buf)
my_commands->type = 0; /* until set */
my_commands->argc = 0;
+#define LOCATION(what) \
+ fprintf(stderr, "error while processing \"%s\" line %d: %s\n", \
+ source, lineno, what)
+
+#define LOCATE() LOCATION(my_commands->line)
+
+#define ERROR(...) \
+ { \
+ LOCATE(); \
+ fprintf(stderr, __VA_ARGS__); \
+ exit(1); \
+ }
+
if (*p == '\\')
{
+ int max_args = -1;
my_commands->type = META_COMMAND;
j = 0;
tok = strtok(++p, delim);
+ if (tok != NULL && pg_strcasecmp(tok, "set") == 0)
+ max_args = 2;
+
while (tok != NULL)
{
my_commands->argv[j++] = pg_strdup(tok);
my_commands->argc++;
- tok = strtok(NULL, delim);
+ if (max_args >= 0 && my_commands->argc >= max_args)
+ tok = strtok(NULL, "");
+ else
+ tok = strtok(NULL, delim);
}
if (pg_strcasecmp(my_commands->argv[0], "setrandom") == 0)
@@ -2202,10 +2256,7 @@ process_commands(char *buf)
*/
if (my_commands->argc < 4)
- {
- fprintf(stderr, "%s: missing argument\n", my_commands->argv[0]);
- exit(1);
- }
+ ERROR("%s: missing argument\n", my_commands->argv[0]);
/* argc >= 4 */
if (my_commands->argc == 4 || /* uniform without/with "uniform" keyword */
@@ -2220,11 +2271,12 @@ process_commands(char *buf)
{
if (my_commands->argc < 6)
{
- fprintf(stderr, "%s(%s): missing threshold argument\n", my_commands->argv[0], my_commands->argv[4]);
- exit(1);
+ ERROR("%s(%s): missing threshold argument\n",
+ my_commands->argv[0], my_commands->argv[4]);
}
else if (my_commands->argc > 6)
{
+ LOCATE();
fprintf(stderr, "%s(%s): too many arguments (extra:",
my_commands->argv[0], my_commands->argv[4]);
for (j = 6; j < my_commands->argc; j++)
@@ -2235,7 +2287,9 @@ process_commands(char *buf)
}
else /* cannot parse, unexpected arguments */
{
- fprintf(stderr, "%s: unexpected arguments (bad:", my_commands->argv[0]);
+ LOCATE();
+ fprintf(stderr, "%s: unexpected arguments (bad:",
+ my_commands->argv[0]);
for (j = 4; j < my_commands->argc; j++)
fprintf(stderr, " %s", my_commands->argv[j]);
fprintf(stderr, ")\n");
@@ -2245,22 +2299,24 @@ process_commands(char *buf)
else if (pg_strcasecmp(my_commands->argv[0], "set") == 0)
{
if (my_commands->argc < 3)
- {
- fprintf(stderr, "%s: missing argument\n", my_commands->argv[0]);
+ ERROR("%s: missing argument\n", my_commands->argv[0]);
+
+ expr_scanner_init(my_commands->argv[2]);
+
+ if (expr_yyparse() != 0) {
+ LOCATION(my_commands->argv[2]);
+ fprintf(stderr, "bogus input\n");
exit(1);
}
- for (j = my_commands->argc < 5 ? 3 : 5; j < my_commands->argc; j++)
- fprintf(stderr, "%s: extra argument \"%s\" ignored\n",
- my_commands->argv[0], my_commands->argv[j]);
+ my_commands->expr = expr_parse_result;
+
+ expr_scanner_finish();
}
else if (pg_strcasecmp(my_commands->argv[0], "sleep") == 0)
{
if (my_commands->argc < 2)
- {
- fprintf(stderr, "%s: missing argument\n", my_commands->argv[0]);
- exit(1);
- }
+ ERROR("%s: missing argument\n", my_commands->argv[0]);
/*
* Split argument into number and unit to allow "sleep 1ms" etc.
@@ -2288,12 +2344,12 @@ process_commands(char *buf)
pg_strcasecmp(my_commands->argv[2], "ms") != 0 &&
pg_strcasecmp(my_commands->argv[2], "s") != 0)
{
- fprintf(stderr, "%s: unknown time unit '%s' - must be us, ms or s\n",
- my_commands->argv[0], my_commands->argv[2]);
- exit(1);
+ ERROR("%s: unknown time unit '%s' - must be us, ms or s\n",
+ my_commands->argv[0], my_commands->argv[2]);
}
}
+ /* should really report an error and stop... */
for (j = 3; j < my_commands->argc; j++)
fprintf(stderr, "%s: extra argument \"%s\" ignored\n",
my_commands->argv[0], my_commands->argv[j]);
@@ -2301,23 +2357,16 @@ process_commands(char *buf)
else if (pg_strcasecmp(my_commands->argv[0], "setshell") == 0)
{
if (my_commands->argc < 3)
- {
- fprintf(stderr, "%s: missing argument\n", my_commands->argv[0]);
- exit(1);
- }
+ ERROR("%s: missing argument\n", my_commands->argv[0]);
}
else if (pg_strcasecmp(my_commands->argv[0], "shell") == 0)
{
if (my_commands->argc < 1)
- {
- fprintf(stderr, "%s: missing command\n", my_commands->argv[0]);
- exit(1);
- }
+ ERROR("%s: missing command\n", my_commands->argv[0]);
}
else
{
- fprintf(stderr, "Invalid command %s\n", my_commands->argv[0]);
- exit(1);
+ ERROR("Invalid command %s\n", my_commands->argv[0]);
}
}
else
@@ -2341,6 +2390,9 @@ process_commands(char *buf)
}
return my_commands;
+
+#undef LOCATE
+#undef ERROR
}
/*
@@ -2393,7 +2445,7 @@ process_file(char *filename)
Command **my_commands;
FILE *fd;
- int lineno;
+ int lineno, index;
char *buf;
int alloc_num;
@@ -2416,22 +2468,24 @@ process_file(char *filename)
}
lineno = 0;
+ index = 0;
while ((buf = read_line_from_file(fd)) != NULL)
{
Command *command;
+ lineno += 1;
- command = process_commands(buf);
+ command = process_commands(buf, filename, lineno);
free(buf);
if (command == NULL)
continue;
- my_commands[lineno] = command;
- lineno++;
+ my_commands[index] = command;
+ index++;
- if (lineno >= alloc_num)
+ if (index >= alloc_num)
{
alloc_num += COMMANDS_ALLOC_NUM;
my_commands = pg_realloc(my_commands, sizeof(Command *) * alloc_num);
@@ -2439,7 +2493,7 @@ process_file(char *filename)
}
fclose(fd);
- my_commands[lineno] = NULL;
+ my_commands[index] = NULL;
sql_files[num_files++] = my_commands;
@@ -2447,12 +2501,12 @@ process_file(char *filename)
}
static Command **
-process_builtin(char *tb)
+process_builtin(char *tb, const char * source)
{
#define COMMANDS_ALLOC_NUM 128
Command **my_commands;
- int lineno;
+ int lineno, index;
char buf[BUFSIZ];
int alloc_num;
@@ -2460,6 +2514,7 @@ process_builtin(char *tb)
my_commands = (Command **) pg_malloc(sizeof(Command *) * alloc_num);
lineno = 0;
+ index = 0;
for (;;)
{
@@ -2478,21 +2533,23 @@ process_builtin(char *tb)
*p = '\0';
- command = process_commands(buf);
+ lineno += 1;
+
+ command = process_commands(buf, source, lineno);
if (command == NULL)
continue;
- my_commands[lineno] = command;
- lineno++;
+ my_commands[index] = command;
+ index++;
- if (lineno >= alloc_num)
+ if (index >= alloc_num)
{
alloc_num += COMMANDS_ALLOC_NUM;
my_commands = pg_realloc(my_commands, sizeof(Command *) * alloc_num);
}
}
- my_commands[lineno] = NULL;
+ my_commands[index] = NULL;
return my_commands;
}
@@ -3222,17 +3279,20 @@ main(int argc, char **argv)
switch (ttype)
{
case 0:
- sql_files[0] = process_builtin(tpc_b);
+ sql_files[0] = process_builtin(tpc_b,
+ "<builtin: TPC-B (sort of)>");
num_files = 1;
break;
case 1:
- sql_files[0] = process_builtin(select_only);
+ sql_files[0] = process_builtin(select_only,
+ "<builtin: select only>");
num_files = 1;
break;
case 2:
- sql_files[0] = process_builtin(simple_update);
+ sql_files[0] = process_builtin(simple_update,
+ "<builtin: simple update>");
num_files = 1;
break;
diff --git a/contrib/pgbench/pgbench.h b/contrib/pgbench/pgbench.h
new file mode 100644
index 0000000..128bf11
--- /dev/null
+++ b/contrib/pgbench/pgbench.h
@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * pgbench.h
+ *
+ * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef PGBENCH_H
+#define PGBENCH_H
+
+typedef enum PgBenchExprType
+{
+ ENODE_INTEGER_CONSTANT,
+ ENODE_VARIABLE,
+ ENODE_OPERATOR
+} PgBenchExprType;
+
+struct PgBenchExpr;
+typedef struct PgBenchExpr PgBenchExpr;
+
+struct PgBenchExpr
+{
+ PgBenchExprType etype;
+ union
+ {
+ struct
+ {
+ int64 ival;
+ } integer_constant;
+ struct
+ {
+ char *varname;
+ } variable;
+ struct
+ {
+ char operator;
+ PgBenchExpr *lexpr;
+ PgBenchExpr *rexpr;
+ } operator;
+ } u;
+};
+
+extern PgBenchExpr *expr_parse_result;
+
+extern int expr_yyparse(void);
+extern int expr_yylex(void);
+extern void expr_yyerror(const char *str);
+extern void expr_scanner_init(const char *str);
+extern void expr_scanner_finish(void);
+
+extern int64 strtoint64(const char *str);
+
+#endif
diff --git a/doc/src/sgml/pgbench.sgml b/doc/src/sgml/pgbench.sgml
index 7d203cd..d3b9043 100644
--- a/doc/src/sgml/pgbench.sgml
+++ b/doc/src/sgml/pgbench.sgml
@@ -751,22 +751,25 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
<variablelist>
<varlistentry>
<term>
- <literal>\set <replaceable>varname</> <replaceable>operand1</> [ <replaceable>operator</> <replaceable>operand2</> ]</literal>
+ <literal>\set <replaceable>varname</> <replaceable>expression</>
</term>
<listitem>
<para>
- Sets variable <replaceable>varname</> to a calculated integer value.
- Each <replaceable>operand</> is either an integer constant or a
- <literal>:</><replaceable>variablename</> reference to a variable
- having an integer value. The <replaceable>operator</> can be
- <literal>+</>, <literal>-</>, <literal>*</>, or <literal>/</>.
+ Sets variable <replaceable>varname</> to an integer value calculated
+ from <replaceable>expression</>.
+ The expression may contain integer constants such as <literal>5432</>,
+ references to variables <literal>:</><replaceable>variablename</>,
+ and expressions composed of unary (<literal>-</>) or binary operators
+ (<literal>+</>, <literal>-</>, <literal>*</>, <literal>/</>, <literal>%</>)
+ with their usual associativity and possibly parentheses.
</para>
<para>
- Example:
+ Examples:
<programlisting>
\set ntellers 10 * :scale
+\set aid (1021 * :aid) % (100000 * :scale) + 1
</programlisting></para>
</listitem>
</varlistentry>
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