from:"\"Raúl Marín Rodríguez\""

[HACKERS] pow support for pgbench

2017-10-30 Thread Raúl Marín Rodríguez

Hi,

I've written a small patch to add support for pow() in pgbench.

The main reason behind it is that I'm currently using a shell call to do it
which takes between 2-10 ms that can be a big percentage of the time taken
by the whole transaction. For example (shortened):

latency average = 11.718 ms
 - statement latencies in milliseconds:
 2.834  \setshell POWER2  awk 'BEGIN {p=2^ARGV[1]; print p }'
:ZOOM_CURRENT
 8.846  SELECT
ST_AsBinary(ST_Simplify(ST_SnapToGrid("the_geom_webmercator",:SNAP),
:SIMPLIFY)) AS geom FROM

I've also updated the related docs and added some tests. Please let me know
if I'm missing anything.

Regards,
*Raúl Marín Rodríguez*
carto.com
From 08a4d519e0c73d0f16acd9e5db9e5b547a884902 Mon Sep 17 00:00:00 2001
From: Raul Marin 
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| 9 +
 src/bin/pgbench/pgbench.h| 3 ++-
 src/bin/pgbench/t/001_pgbench_with_server.pl | 7 ++-
 5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index e509e6c7f62..e12a149c5bb 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -1022,6 +1022,13 @@ pgbench  options  d
sqrt(2.0)
1.414213562
   
+  
+   pow(x, y)
+   double if x or y are doubles, else integer
+   Numeric exponentiation
+   pow(2.0, 10)
+   1024.0/
+  
  
  

diff --git a/src/bin/pgbench/exprparse.y b/src/bin/pgbench/exprparse.y
index b3a2d9bfd37..4db3b215abf 100644
--- a/src/bin/pgbench/exprparse.y
+++ b/src/bin/pgbench/exprparse.y
@@ -191,6 +191,9 @@ static const struct
 	{
 		"random_exponential", 3, PGBENCH_RANDOM_EXPONENTIAL
 	},
+	{
+		"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 5d8a01c72cf..a3aef108f84 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -1346,6 +1346,7 @@ evalFunc(TState *thread, CState *st,
 		case PGBENCH_MUL:
 		case PGBENCH_DIV:
 		case PGBENCH_MOD:
+		case PGBENCH_POW:
 			{
 PgBenchValue *lval = &vargs[0],
 		   *rval = &vargs[1];
@@ -1381,6 +1382,10 @@ evalFunc(TState *thread, CState *st,
 			setDoubleValue(retval, ld / rd);
 			return true;
 
+		case PGBENCH_POW:
+			setDoubleValue(retval, pow(ld, rd));
+			return true;
+
 		default:
 			/* cannot get here */
 			Assert(0);
@@ -1442,6 +1447,10 @@ evalFunc(TState *thread, CState *st,
 
 			return true;
 
+		case PGBENCH_POW:
+			setIntValue(retval, pow(li, ri));
+			return true;
+
 		default:
 			/* cannot get here */
 			Assert(0);
diff --git a/src/bin/pgbench/pgbench.h b/src/bin/pgbench/pgbench.h
index fd428af274f..e0132b5fcf6 100644
--- a/src/bin/pgbench/pgbench.h
+++ b/src/bin/pgbench/pgbench.h
@@ -75,7 +75,8 @@ typedef enum PgBenchFunction
 	PGBENCH_SQRT,
 	PGBENCH_RANDOM,
 	PGBENCH_RANDOM_GAUSSIAN,
-	PGBENCH_RANDOM_EXPONENTIAL
+	PGBENCH_RANDOM_EXPONENTIAL,
+	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 11bc0fecfef..601c7ee0e4d 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -218,7 +218,9 @@ sub pgbench
 		qr{command=18.: double 18\b},
 		qr{command=19.: double 19\b},
 		qr{command=20.: double 20\b},
-		qr{command=21.: int 9223372036854775807\b}, ],
+		qr{command=21.: int 9223372036854775807\b},
+		qr{command=23.: int -27\b},
+		qr{command=24.: double 1024\b}, ],
 	'pgbench expressions',
 	{   '001_pgbench_expressions' => q{-- integer functions
 \set i1 debug(random(1, 100))
@@ -248,6 +250,9 @@ sub pgbench
 \set maxint debug(:minint - 1)
 -- reset a variable
 \set i1 0
+--- pow() operator
+\set poweri debug(pow(-3,3))
+\set powerd debug(pow(2.0,10))
 } });
 
 # backslash commands

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Re: [HACKERS] pow support for pgbench

2017-10-30 Thread Raúl Marín Rodríguez

Sorry about the patch. Attaching it now so it can be considered as
submitted.

-- 

*Raúl Marín Rodríguez*carto.com
From a6eecfe6637bdb0cbb02a9eda7b88d9c4325bb51 Mon Sep 17 00:00:00 2001
From: Raul Marin 
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| 9 +
 src/bin/pgbench/pgbench.h| 3 ++-
 src/bin/pgbench/t/001_pgbench_with_server.pl | 5 +
 5 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 1f55967e40a..2e913dfcfd6 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -1233,6 +1233,13 @@ pgbench  options  d
sqrt(2.0)
1.414213562
   
+  
+   pow(x, y)
+   double if x or y are doubles, else integer
+   Numeric exponentiation
+   pow(2.0, 10)
+   1024.0/
+  
  
  

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..b2bab9b8239 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -1474,6 +1474,7 @@ evalFunc(TState *thread, CState *st,
 		case PGBENCH_NE:
 		case PGBENCH_LE:
 		case PGBENCH_LT:
+		case PGBENCH_POW:
 			{
 PgBenchValue *lval = &vargs[0],
 		   *rval = &vargs[1];
@@ -1525,6 +1526,10 @@ evalFunc(TState *thread, CState *st,
 			setBoolValue(retval, ld < rd);
 			return true;
 
+		case PGBENCH_POW:
+			setDoubleValue(retval, pow(ld, rd));
+			return true;
+
 		default:
 			/* cannot get here */
 			Assert(0);
@@ -1602,6 +1607,10 @@ evalFunc(TState *thread, CState *st,
 
 			return true;
 
+		case PGBENCH_POW:
+			setIntValue(retval, pow(li, ri));
+			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..81b7ce4dfcc 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -237,6 +237,8 @@ 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},
 	],
 	'pgbench expressions',
 	{   '001_pgbench_expressions' => q{-- integer functions
@@ -299,6 +301,9 @@ 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))
 } });
 
 =head

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Re: [HACKERS] pow support for pgbench

2017-10-30 Thread Raúl Marín Rodríguez

Hi,

both patches seem complementary. I've rebased my changes on top of that
patch
(v14) in https://git.io/vFtnT and everything seems to be working fine.

On Mon, Oct 30, 2017 at 12:36 PM, Michael Paquier  wrote:

> On Mon, Oct 30, 2017 at 11:07 AM, Alvaro Herrera
>  wrote:
> > Michael Paquier wrote:
> >
> >> Please add this patch to the upcoming commit fest if you would like to
> >> get some feedback:
> >> https://commitfest.postgresql.org/15/
> >>
> >> I am adding as well Fabien in CC who worked in getting the internal
> >> function infrastructure in the shape it is now (waaay better) with
> >> commit 86c43f4.
> >
> > I think Raúl would do well to review this patch by Fabien
> > https://www.postgresql.org/message-id/alpine.DEB.2.20.
> 1710201835390.15170@lancre
> > which adds a few functions and operators.
>
> Good idea. pow() is not added by Fabien's patch, but an operator for
> pow() could be something to add as well.
> --
> Michael
>



-- 

*Raúl Marín Rodríguez*carto.com

Re: [HACKERS] pow support for pgbench

2017-11-06 Thread Raúl Marín Rodríguez

Hi Fabien,

Thanks for the review.
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.

On Sat, Nov 4, 2017 at 12:34 PM, Fabien COELHO  wrote:

>
> Hello Raúl,
>
> Sorry about the patch. Attaching it now so it can be considered as
>> submitted.
>>
>
> There is a typo in the XML doc:
>
> 1024.0/
>
> Please check that the documentation compiles.
>
> I'm at odds with having the integer version rely on a double pow(), even
> if it works. I think that there should be a specific integer version which
> does use integer operations. From stack overflow, the following is
> suggested:
>
>  int ipow(int base, int exp)
>  {
> int result = 1;
> while (exp)
> {
> if (exp & 1)
> result *= base;
> exp >>= 1;
> base *= base;
> }
>
> return result;
>  }
>
> The integer version should be when x & y are integers *AND* y >= 0.
>
> if y is a negative integer, the double version should be used.
>
> --
> Fabien.




-- 

*Raúl Marín Rodríguez*carto.com
From 09105f8108e439834510ee5fb53036473f2977d5 Mon Sep 17 00:00:00 2001
From: Raul Marin 
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| 54 
 src/bin/pgbench/pgbench.h|  3 +-
 src/bin/pgbench/t/001_pgbench_with_server.pl |  9 +
 5 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 1f55967e40a..4e7f75ddf87 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -1233,6 +1233,13 @@ pgbench  options  d
sqrt(2.0)
1.414213562
   
+  
+   pow(x, y)
+   double if x or y are doubles, else integer
+   Numeric exponentiation
+   pow(2.0, 10)
+   1024.0
+  
  
  

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..bdf3e97682a 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
@@ -1474,6 +1519,7 @@ evalFunc(TState *thread, CState *st,
 		case PGBENCH_NE:
 		case PGBENCH_LE:
 		case PGBENCH_LT:
+		case PGBENCH_POW:
 			{
 PgBenchValue *lval = &vargs[0],
 		   *rval = &vargs[1];
@@ -1525,6 +1571,10 @@ evalFunc(TState *thread, CState *st,
 			setBoolValue(retval, ld < rd);
 			return true;
 
+		case PGBENCH_POW:
+			setDoubleValue(retval, pow(ld, rd));
+			return true;
+
 		default:
 			/* cannot get here */
 			Assert(0);
@@ -1602,6 +1652,10 @@ evalFunc(TState *thread, CState *st,
 
 			return true;
 
+		case PGBENCH_POW:
+			setIntValue(retval, ipow(li, ri));
+			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..c5ecd749c40 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgb

Re: [HACKERS] pow support for pgbench

2017-11-06 Thread Raúl Marín Rodríguez

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  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 
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  options  d
sqrt(2.0)
1.414213562
   
+  
+   pow(x, y)
+   integer if x and y are integers and y >= 0, else double
+   Numeric exponentiation
+   pow(2.0, 10)
+   1024.0
+  
  
  

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/bi

Re: [HACKERS] pow support for pgbench

2017-11-06 Thread Raúl Marín Rodríguez

Hi,


Indeed, this is quite strange...


 I don't want to go too deep into it, but you get stuff like this:

Select pow(2.0, -3)::text = pow(2, -3)::text;
 ?column?
--
 f
(1 row)


 - you can simplify the ipow function by removing handling of y<0 case,
>maybe add an assert to be sure to avoid it.

I agree, done.

 - you should add more symmetry and simplify the evaluation:

Done too.

 Add a test case to show what happens on NULL arguments, hopefully the
> result is NULL.

Done and it does.

Thanks again for the review.

On Mon, Nov 6, 2017 at 4:14 PM, Fabien COELHO  wrote:

>
> Hello,
>
> Sorry for the confusion, I wasn't aware that SQL pow changed types
>> depending on the input value.
>>
>
> Indeed, this is quite strange...
>
>   fabien=# SELECT i, POW(2, i) FROM generate_series(-2, 2) AS i;
>-2 | 0.25
>-1 | 0.5
> 0 | 1
> 1 | 2
> 2 | 4
>
> 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?
>>
>
>   fabien=# SELECT POW(0,-1);
>   ERROR:  zero raised to a negative power is undefined
>
> H... I'm fine with double inf, because exception in pgbench means the
> end of the script, which is not desirable for benchmarking purposes.
>
> I think that:
>
>  - you can simplify the ipow function by removing handling of y<0 case,
>maybe add an assert to be sure to avoid it.
>
>  - you should add more symmetry and simplify the evaluation:
>
>if (int & int)
>{
>   i1, i2 = ...;
>   if (i2 >= 0)
> setIntValue(retval, ipow(i1, i2));
>   else
> // conversion is done by C, no need to coerce again
> setDoubleValue(retval, pow(i1, i2));
>}
>else
>    {
>  d1, d2 = ...;
>  setDoubleValue(retval, pow(d1, d2));
>}
>
> Add a test case to show what happens on NULL arguments, hopefully the
> result is NULL.
>
> --
> Fabien.
>



-- 

*Raúl Marín Rodríguez *carto.com
From 47f6ec396d3bc11c39066dbd4b31e75b76102094 Mon Sep 17 00:00:00 2001
From: Raul Marin 
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| 62 
 src/bin/pgbench/pgbench.h|  3 +-
 src/bin/pgbench/t/001_pgbench_with_server.pl | 15 +++
 5 files changed, 89 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  options  d
sqrt(2.0)
1.414213562
   
+  
+   pow(x, y)
+   integer if x and y are integers and y >= 0, else double
+   Numeric exponentiation
+   pow(2.0, 10)
+   1024.0
+  
  
  

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..3781e75721d 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -739,6 +739,27 @@ getPoissonRand(TState *thread, int64 center)
 }
 
 /*
+ * pow() for integer values with exp >= 0. Matches SQL pow() behaviour
+ */
+static int64
+ipow(int64 base, int64 exp)
+{
+	int64 result = 1;
+
+	Assert(exp >= 0);
+
+	while (exp)
+	{
+		if (exp & 1)
+			result *= base;
+		exp >>= 1;
+		base *= base;
+	}
+
+	return result;
+}
+
+/*
  * Initialize the given SimpleStats struct to all zeroes
  */
 static void
@@ -1918,6 +1939,47 @@ evalFunc(TState *thread, CState *st,
 return true;
 			}
 
+		case PGBENCH_POW:
+			{
+PgBenchValue *lval = &vargs[0];
+PgBenchValue *rval = &vargs[1];
+
+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));
+	else
+		setDoubleValue(retval, pow(li, ri));
+}
+else
+{
+	double		ld,
+rd;
+
+	if (!coerceToDouble(lval, &ld)

[HACKERS] pow support for pgbench

Re: [HACKERS] pow support for pgbench

Re: [HACKERS] pow support for pgbench

Re: [HACKERS] pow support for pgbench

Re: [HACKERS] pow support for pgbench

Re: [HACKERS] pow support for pgbench

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