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Rename pgbench min/max to least/greatest, and fix handling of double args.

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These functions behave like the backend's least/greatest functions,
not like min/max, so the originally-chosen names invite confusion.
Per discussion, rename to least/greatest.

I also took it upon myself to make them return double if any input is
double.  The previous behavior of silently coercing all inputs to int
surely does not meet the principle of least astonishment.

Copy-edit some of the other new functions' documentation, too.
This commit is contained in:
Tom Lane
2016-05-05 14:51:00 -04:00
parent c311f78873
commit 7a622b2731
4 changed files with 69 additions and 36 deletions
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25
doc/src/sgml/ref/pgbench.sgml
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@ -935,14 +935,15 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
<row>
<entry><literal><function>abs(<replaceable>a</>)</></></>
<entry>same as <replaceable>a</></>
<entry>integer or double absolute value</>
<entry>absolute value</>
<entry><literal>abs(-17)</></>
<entry><literal>17</></>
</row>
<row>
<entry><literal><function>debug(<replaceable>a</>)</></></>
<entry>same as <replaceable>a</> </>
<entry>print to <systemitem>stderr</systemitem> the given argument</>
<entry>print <replaceable>a</> to <systemitem>stderr</systemitem>,
and return <replaceable>a</></>
<entry><literal>debug(5432.1)</></>
<entry><literal>5432.1</></>
</row>
@ -961,23 +962,23 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
<entry><literal>9</></>
</row>
<row>
<entry><literal><function>max(<replaceable>i</> [, <replaceable>...</> ] )</></></>
<entry>integer</>
<entry>maximum value</>
<entry><literal>max(5, 4, 3, 2)</></>
<entry><literal><function>greatest(<replaceable>a</> [, <replaceable>...</> ] )</></></>
<entry>double if any <replaceable>a</> is double, else integer</>
<entry>largest value among arguments</>
<entry><literal>greatest(5, 4, 3, 2)</></>
<entry><literal>5</></>
</row>
<row>
<entry><literal><function>min(<replaceable>i</> [, <replaceable>...</> ] )</></></>
<entry>integer</>
<entry>minimum value</>
<entry><literal>min(5, 4, 3, 2)</></>
<entry><literal>2</></>
<entry><literal><function>least(<replaceable>a</> [, <replaceable>...</> ] )</></></>
<entry>double if any <replaceable>a</> is double, else integer</>
<entry>smallest value among arguments</>
<entry><literal>least(5, 4, 3, 2.1)</></>
<entry><literal>2.1</></>
</row>
<row>
<entry><literal><function>pi()</></></>
<entry>double</>
<entry>value of the PI constant</>
<entry>value of the constant PI</>
<entry><literal>pi()</></>
<entry><literal>3.14159265358979323846</></>
</row>

8
src/bin/pgbench/exprparse.y
View File

@ -131,7 +131,7 @@ make_op(yyscan_t yyscanner, const char *operator,
* List of available functions:
* - fname: function name
* - nargs: number of arguments
* -1 is a special value for min & max meaning #args >= 1
* -1 is a special value for least & greatest meaning #args >= 1
* - tag: function identifier from PgBenchFunction enum
*/
static const struct
@ -162,10 +162,10 @@ static const struct
"abs", 1, PGBENCH_ABS
},
{
"min", -1, PGBENCH_MIN
"least", -1, PGBENCH_LEAST
},
{
"max", -1, PGBENCH_MAX
"greatest", -1, PGBENCH_GREATEST
},
{
"debug", 1, PGBENCH_DEBUG
@ -274,7 +274,7 @@ make_func(yyscan_t yyscanner, int fnumber, PgBenchExprList *args)
expr_yyerror_more(yyscanner, "unexpected number of arguments",
PGBENCH_FUNCTIONS[fnumber].fname);
/* check at least one arg for min & max */
/* check at least one arg for least & greatest */
if (PGBENCH_FUNCTIONS[fnumber].nargs == -1 &&
elist_length(args) == 0)
expr_yyerror_more(yyscanner, "at least one argument expected",

68
src/bin/pgbench/pgbench.c
View File

@ -1298,31 +1298,63 @@ evalFunc(TState *thread, CState *st,
return true;
}
/* variable number of int arguments */
case PGBENCH_MIN:
case PGBENCH_MAX:
/* variable number of arguments */
case PGBENCH_LEAST:
case PGBENCH_GREATEST:
{
int64 extremum;
bool havedouble;
int i;
Assert(nargs >= 1);
if (!coerceToInt(&vargs[0], &extremum))
return false;
for (i = 1; i < nargs; i++)
/* need double result if any input is double */
havedouble = false;
for (i = 0; i < nargs; i++)
{
int64 ival;
if (!coerceToInt(&vargs[i], &ival))
return false;
if (func == PGBENCH_MIN)
extremum = extremum < ival ? extremum : ival;
else if (func == PGBENCH_MAX)
extremum = extremum > ival ? extremum : ival;
if (vargs[i].type == PGBT_DOUBLE)
{
havedouble = true;
break;
}
}
if (havedouble)
{
double extremum;
setIntValue(retval, extremum);
if (!coerceToDouble(&vargs[0], &extremum))
return false;
for (i = 1; i < nargs; i++)
{
double dval;
if (!coerceToDouble(&vargs[i], &dval))
return false;
if (func == PGBENCH_LEAST)
extremum = Min(extremum, dval);
else
extremum = Max(extremum, dval);
}
setDoubleValue(retval, extremum);
}
else
{
int64 extremum;
if (!coerceToInt(&vargs[0], &extremum))
return false;
for (i = 1; i < nargs; i++)
{
int64 ival;
if (!coerceToInt(&vargs[i], &ival))
return false;
if (func == PGBENCH_LEAST)
extremum = Min(extremum, ival);
else
extremum = Max(extremum, ival);
}
setIntValue(retval, extremum);
}
return true;
}

4
src/bin/pgbench/pgbench.h
View File

@ -67,8 +67,8 @@ typedef enum PgBenchFunction
PGBENCH_MOD,
PGBENCH_DEBUG,
PGBENCH_ABS,
PGBENCH_MIN,
PGBENCH_MAX,
PGBENCH_LEAST,
PGBENCH_GREATEST,
PGBENCH_INT,
PGBENCH_DOUBLE,
PGBENCH_PI,