Hi Fabien,
Sorry for the confusion, I wasn't aware that SQL pow changed types
depending on
the input value.
I've modified the function to match more closely the behaviour of SQL,
except
that 0^(negative) returns 'double inf'. Do you think there is any value in
raising an error instead?
On Mon, Nov 6, 2017 at 2:12 PM, Fabien COELHO <coe...@cri.ensmp.fr> wrote:
>
> Hello Raúl,
>
> I've fixed the documentation and added an ipow function that handles both
>> positive and negative ints, having 0^0 == 1 and 0^(negative) ==
>> PG_INT64_MAX
>> since that's what my glibc math.h pow() is returning.
>>
>
> From the comment:
>
> * For exp < 0 return 0 except when the base is 1 or -1
>
> I think that it should do what POW does in psql, i.e.:
>
> fabien=# SELECT POW(2, -2); # 0.25
>
> that is if exp < 0 the double version should be used, it should
> not return 0.
>
> Basically the idea is that the pgbench client-side version should behave
> the same as the SQL version.
>
> --
> Fabien.
--
*Raúl Marín Rodríguez*carto.com
From be2fedcae277f7eede621dcda66b15b08372ce63 Mon Sep 17 00:00:00 2001
From: Raul Marin <rmrodrig...@cartodb.com>
Date: Fri, 13 Oct 2017 17:42:23 +0200
Subject: [PATCH] Add pow() support to pgbench
---
doc/src/sgml/ref/pgbench.sgml | 7 +++
src/bin/pgbench/exprparse.y | 3 +
src/bin/pgbench/pgbench.c | 84 ++++++++++++++++++++++++++++
src/bin/pgbench/pgbench.h | 3 +-
src/bin/pgbench/t/001_pgbench_with_server.pl | 13 +++++
5 files changed, 109 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 1f55967e40a..32c94ba0dc1 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -1233,6 +1233,13 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
<entry><literal>sqrt(2.0)</literal></entry>
<entry><literal>1.414213562</literal></entry>
</row>
+ <row>
+ <entry><literal><function>pow(<replaceable>x</replaceable>, <replaceable>y</replaceable>)</function></literal></entry>
+ <entry>integer if <replaceable>x</replaceable> and <replaceable>y</replaceable> are integers and <literal><replaceable>y</replaceable> >= 0</literal>, else double</entry>
+ <entry>Numeric exponentiation</entry>
+ <entry><literal>pow(2.0, 10)</literal></entry>
+ <entry><literal>1024.0</literal></entry>
+ </row>
</tbody>
</tgroup>
</table>
diff --git a/src/bin/pgbench/exprparse.y b/src/bin/pgbench/exprparse.y
index 770be981f06..290bca99d12 100644
--- a/src/bin/pgbench/exprparse.y
+++ b/src/bin/pgbench/exprparse.y
@@ -334,6 +334,9 @@ static const struct
{
"!case_end", -2, PGBENCH_CASE
},
+ {
+ "pow", 2, PGBENCH_POW
+ },
/* keep as last array element */
{
NULL, 0, 0
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index add653bf90c..d565880b6e2 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -739,6 +739,51 @@ getPoissonRand(TState *thread, int64 center)
}
/*
+ * pow() for integer values
+ */
+static int64
+ipow(int64 base, int64 exp)
+{
+ int64 result;
+
+ if (base == 0)
+ {
+ if (exp > 0)
+ return 0;
+ else if (exp == 0)
+ return 1;
+ return PG_INT64_MAX;
+ }
+
+ /*
+ * For exp > 0 calculate normally
+ * For exp == 0 return 1 * sign of base
+ * For exp < 0 return 0 except when the base is 1 or -1
+ */
+ if (exp > 0)
+ {
+ result = 1;
+ while (exp)
+ {
+ if (exp & 1)
+ result *= base;
+ exp >>= 1;
+ base *= base;
+ }
+ }
+ else if (exp == 0)
+ result = (base > 0) - (base < 0);
+ else
+ {
+ result = 1 / base;
+ if (exp % 2 == 0)
+ result *= result;
+ }
+
+ return result;
+}
+
+/*
* Initialize the given SimpleStats struct to all zeroes
*/
static void
@@ -1918,6 +1963,45 @@ evalFunc(TState *thread, CState *st,
return true;
}
+ case PGBENCH_POW:
+ {
+ PgBenchValue *lval = &vargs[0];
+ PgBenchValue *rval = &vargs[1];
+ double ld,
+ rd;
+
+ Assert(nargs == 2);
+
+ /*
+ * If both operands are int and exp >= 0 use
+ * the ipow() function, else use pow()
+ */
+ if (lval->type == PGBT_INT &&
+ rval->type == PGBT_INT)
+ {
+
+ int64 li,
+ ri;
+
+ if (!coerceToInt(lval, &li) ||
+ !coerceToInt(rval, &ri))
+ return false;
+
+ if (ri >= 0)
+ {
+ setIntValue(retval, ipow(li, ri));
+ return true;
+ }
+ }
+
+ if (!coerceToDouble(lval, &ld) ||
+ !coerceToDouble(rval, &rd))
+ return false;
+
+ setDoubleValue(retval, pow(ld, rd));
+ return true;
+ }
+
default:
/* cannot get here */
Assert(0);
diff --git a/src/bin/pgbench/pgbench.h b/src/bin/pgbench/pgbench.h
index e1277a1dde6..9f26af92bf6 100644
--- a/src/bin/pgbench/pgbench.h
+++ b/src/bin/pgbench/pgbench.h
@@ -94,7 +94,8 @@ typedef enum PgBenchFunction
PGBENCH_LE,
PGBENCH_LT,
PGBENCH_IS,
- PGBENCH_CASE
+ PGBENCH_CASE,
+ PGBENCH_POW
} PgBenchFunction;
typedef struct PgBenchExpr PgBenchExpr;
diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index 8e19bbd3f45..2a1bb1216d7 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -237,6 +237,12 @@ sub pgbench
qr{command=36.: int 36\b},
qr{command=37.: boolean true\b},
qr{command=38.: boolean true\b},
+ qr{command=44.: int -27\b},
+ qr{command=45.: double 1024\b},
+ qr{command=46.: int 1\b},
+ qr{command=47.: double 1\b},
+ qr{command=48.: double -0.125\b},
+ qr{command=49.: double -0.125\b},
],
'pgbench expressions',
{ '001_pgbench_expressions' => q{-- integer functions
@@ -299,6 +305,13 @@ sub pgbench
\set v2 5432
\set v3 -54.21E-2
SELECT :v0, :v1, :v2, :v3;
+--- pow() operator
+\set poweri debug(pow(-3,3))
+\set powerd debug(pow(2.0,10))
+\set poweriz debug(pow(0,0))
+\set powerdz debug(pow(0.0,0.0))
+\set powernegi debug(pow(-2,-3))
+\set powernegd debug(pow(-2.0,-3.0))
} });
=head
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