Hi,
On Monday 01 November 2010 10:15:01 Andres Freund wrote:
> On Monday 01 November 2010 04:04:51 Itagaki Takahiro wrote:
> > On Mon, Nov 1, 2010 at 6:41 AM, Andres Freund <[email protected]> wrote:
> > > While looking at binary COPY performance I forgot to add BINARY and was
> > > a bit shocked to see printf that high in the profile...
> > >
> > > A change from 9192.476ms 5309.928ms seems to be pretty good indication
> > > that a change in that area is waranted given integer columns are quite
> > > ubiquous...
> > > * I renamed pg_[il]toa to pg_s(16|32|64)toa - I found the names
> > > confusing. Not sure if its worth it.
> > Agreed, but how about pg_i(16|32|64)toa? 'i' might be more popular than
> > 's'. See also
> > http://msdn.microsoft.com/en-US/library/yakksftt(VS.100).aspx
> I find itoa not as clear about signedness as stoa, but if you insist, I
> dont feel strongly about it.
Let whover commits it decide...
> > * The buffer reordering seems a bit messy.
> > //have to reorder the string, but not 0byte.
> > I'd suggest to fill a fixed-size local buffer from right to left
> > and copy it to the actual output.
> Is a bit cleaner maybe, but I dont see much point in putting it into its
> own function... But again, I don't feel strongly.
Using a seperate buffer cost nearly 500ms... So I only changed the comments
there.
The only way I could think of to make it faster was to fill the buffer from the
end and then return a pointer to the starting point in the buffer. The speed
benefits are small (around 80ms) and it makes the interface more cumbersome...
Revised version attached - I will submit this to the next comittfest now.
Andres
diff --git a/src/backend/utils/adt/int.c b/src/backend/utils/adt/int.c
index c450333..5340052 100644
--- a/src/backend/utils/adt/int.c
+++ b/src/backend/utils/adt/int.c
@@ -74,7 +74,7 @@ int2out(PG_FUNCTION_ARGS)
int16 arg1 = PG_GETARG_INT16(0);
char *result = (char *) palloc(7); /* sign, 5 digits, '\0' */
- pg_itoa(arg1, result);
+ pg_s16toa(arg1, result);
PG_RETURN_CSTRING(result);
}
@@ -189,7 +189,7 @@ int2vectorout(PG_FUNCTION_ARGS)
{
if (num != 0)
*rp++ = ' ';
- pg_itoa(int2Array->values[num], rp);
+ pg_s16toa(int2Array->values[num], rp);
while (*++rp != '\0')
;
}
@@ -293,7 +293,7 @@ int4out(PG_FUNCTION_ARGS)
int32 arg1 = PG_GETARG_INT32(0);
char *result = (char *) palloc(12); /* sign, 10 digits, '\0' */
- pg_ltoa(arg1, result);
+ pg_s32toa(arg1, result);
PG_RETURN_CSTRING(result);
}
diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 894110d..4de2dfc 100644
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -20,6 +20,7 @@
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "utils/int8.h"
+#include "utils/builtins.h"
#define MAXINT8LEN 25
@@ -158,12 +159,9 @@ int8out(PG_FUNCTION_ARGS)
{
int64 val = PG_GETARG_INT64(0);
char *result;
- int len;
char buf[MAXINT8LEN + 1];
- if ((len = snprintf(buf, MAXINT8LEN, INT64_FORMAT, val)) < 0)
- elog(ERROR, "could not format int8");
-
+ pg_s64toa(val, buf);
result = pstrdup(buf);
PG_RETURN_CSTRING(result);
}
diff --git a/src/backend/utils/adt/numutils.c b/src/backend/utils/adt/numutils.c
index 5f8083f..61b4728 100644
--- a/src/backend/utils/adt/numutils.c
+++ b/src/backend/utils/adt/numutils.c
@@ -3,8 +3,6 @@
* numutils.c
* utility functions for I/O of built-in numeric types.
*
- * integer: pg_atoi, pg_itoa, pg_ltoa
- *
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
@@ -109,27 +107,126 @@ pg_atoi(char *s, int size, int c)
}
/*
- * pg_itoa - converts a short int to its string represention
+ * pg_s32toa - convert a signed 16bit integer to a string representation
*
- * Note:
- * previously based on ~ingres/source/gutil/atoi.c
- * now uses vendor's sprintf conversion
+ * It doesnt seem worth implementing this separately.
*/
void
-pg_itoa(int16 i, char *a)
+pg_s16toa(int16 i, char *a)
{
- sprintf(a, "%hd", (short) i);
+ pg_s32toa((int32)i, a);
}
+
/*
- * pg_ltoa - converts a long int to its string represention
+ * pg_s32toa - convert a signed 32bit integer to a string representation
*
- * Note:
- * previously based on ~ingres/source/gutil/atoi.c
- * now uses vendor's sprintf conversion
+ * Its unfortunate to have this function twice - once for 32bit, once
+ * for 64bit, but incurring the cost of 64bit computation to 32bit
+ * platforms doesn't seem to be acceptable.
*/
void
-pg_ltoa(int32 l, char *a)
-{
- sprintf(a, "%d", l);
+pg_s32toa(int32 value, char *buf){
+ char *bufstart = buf;
+ bool neg = false;
+
+ /*
+ * Avoid problems with the most negative not being representable
+ * as a positive number
+ */
+ if(value == INT32_MIN)
+ {
+ memcpy(buf, "-2147483648", 12);
+ return;
+ }
+ else if(value < 0)
+ {
+ value = -value;
+ neg = true;
+ }
+
+ /* Build the string by computing the wanted string backwards. */
+ do
+ {
+ int32 remainder;
+ int32 oldval = value;
+ /*
+ * division by constants can be optimized by some modern
+ * compilers (including gcc). We could add the concrete,
+ * optimized, calculatation here to be fast at -O0 and/or
+ * other compilers... Not sure if its worth doing.
+ */
+ value /= 10;
+ remainder = oldval - value * 10;
+ *buf++ = '0' + remainder;
+ }
+ while(value != 0);
+
+ if(neg)
+ *buf++ = '-';
+
+ /* have to reorder the string, but not 0 byte */
+ *buf-- = 0;
+
+ /* reverse string */
+ while(bufstart < buf)
+ {
+ char swap = *bufstart;
+ *bufstart++ = *buf;
+ *buf-- = swap;
+ }
+}
+
+/*
+ * pg_s64toa - convert a signed 64bit integer to a string representation
+ */
+void pg_s64toa(int64 value, char *buf){
+ char *bufstart = buf;
+ bool neg = false;
+
+ /*
+ * Avoid problems with the most negative not being representable as
+ * a positive number
+ */
+ if(value == INT64_MIN)
+ {
+ memcpy(buf, "-9223372036854775808", 21);
+ return;
+ }
+ else if(value < 0)
+ {
+ value = -value;
+ neg = true;
+ }
+
+ /* Build the string by computing the wanted string backwards. */
+ do
+ {
+ int64 remainder;
+ int64 oldval = value;
+ /*
+ * division by constants can be optimized by some modern
+ * compilers (including gcc). We could add the concrete,
+ * optimized, calculatation here to be fast at -O0 and/or
+ * other compilers... Not sure if its worth doing.
+ */
+ value /= 10;
+ remainder = oldval - value * 10;
+ *buf++ = '0' + remainder;
+ }
+ while(value != 0);
+
+ if(neg)
+ *buf++ = '-';
+
+ /* have to reorder the string, but not 0 byte */
+ *buf-- = 0;
+
+ /* reverse string */
+ while(bufstart < buf)
+ {
+ char swap = *bufstart;
+ *bufstart++ = *buf;
+ *buf-- = swap;
+ }
}
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index f4b2a96..ba83ef2 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -273,8 +273,10 @@ extern Datum current_schemas(PG_FUNCTION_ARGS);
/* numutils.c */
extern int32 pg_atoi(char *s, int size, int c);
-extern void pg_itoa(int16 i, char *a);
-extern void pg_ltoa(int32 l, char *a);
+
+extern void pg_s16toa(int16 l, char *a);
+extern void pg_s32toa(int32 l, char *a);
+extern void pg_s64toa(int64 l, char *a);
/*
* Per-opclass comparison functions for new btrees. These are
diff --git a/src/test/regress/expected/int2.out b/src/test/regress/expected/int2.out
index 61ac956..3bb26b3 100644
--- a/src/test/regress/expected/int2.out
+++ b/src/test/regress/expected/int2.out
@@ -1,7 +1,5 @@
--
-- INT2
--- NOTE: int2 operators never check for over/underflow!
--- Some of these answers are consequently numerically incorrect.
--
CREATE TABLE INT2_TBL(f1 int2);
INSERT INTO INT2_TBL(f1) VALUES ('0 ');
@@ -244,3 +242,16 @@ SELECT '' AS five, i.f1, i.f1 / int4 '2' AS x FROM INT2_TBL i;
| -32767 | -16383
(5 rows)
+-- corner cases
+SELECT (1<<15-1)::int2::text;
+ text
+-------
+ 16384
+(1 row)
+
+SELECT (-1<<15)::int2::text;
+ text
+--------
+ -32768
+(1 row)
+
diff --git a/src/test/regress/expected/int4.out b/src/test/regress/expected/int4.out
index a21bbda..42095c7 100644
--- a/src/test/regress/expected/int4.out
+++ b/src/test/regress/expected/int4.out
@@ -1,7 +1,5 @@
--
-- INT4
--- WARNING: int4 operators never check for over/underflow!
--- Some of these answers are consequently numerically incorrect.
--
CREATE TABLE INT4_TBL(f1 int4);
INSERT INTO INT4_TBL(f1) VALUES (' 0 ');
@@ -331,3 +329,16 @@ SELECT (2 + 2) / 2 AS two;
2
(1 row)
+-- corner cases
+SELECT (1<<31-1)::int4::text;
+ text
+------------
+ 1073741824
+(1 row)
+
+SELECT (1<<31)::int4::text;
+ text
+-------------
+ -2147483648
+(1 row)
+
diff --git a/src/test/regress/expected/int8.out b/src/test/regress/expected/int8.out
index c8e2dad..e156067 100644
--- a/src/test/regress/expected/int8.out
+++ b/src/test/regress/expected/int8.out
@@ -802,3 +802,16 @@ SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::in
4567890123456799
(6 rows)
+-- corner cases
+SELECT (1<<63-1)::int8::text;
+ text
+------------
+ 1073741824
+(1 row)
+
+SELECT (1<<63)::int8::text;
+ text
+-------------
+ -2147483648
+(1 row)
+
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 8e4286a..e14c985 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -729,7 +729,7 @@ int44out(PG_FUNCTION_ARGS)
walk = result;
for (i = 0; i < 4; i++)
{
- pg_ltoa(an_array[i], walk);
+ pg_s32toa(an_array[i], walk);
while (*++walk != '\0')
;
*walk++ = ' ';
diff --git a/src/test/regress/sql/int2.sql b/src/test/regress/sql/int2.sql
index bf4efba..8bffe53 100644
--- a/src/test/regress/sql/int2.sql
+++ b/src/test/regress/sql/int2.sql
@@ -1,7 +1,5 @@
--
-- INT2
--- NOTE: int2 operators never check for over/underflow!
--- Some of these answers are consequently numerically incorrect.
--
CREATE TABLE INT2_TBL(f1 int2);
@@ -85,3 +83,7 @@ SELECT '' AS five, i.f1, i.f1 - int4 '2' AS x FROM INT2_TBL i;
SELECT '' AS five, i.f1, i.f1 / int2 '2' AS x FROM INT2_TBL i;
SELECT '' AS five, i.f1, i.f1 / int4 '2' AS x FROM INT2_TBL i;
+
+-- corner cases
+SELECT (1<<15-1)::int2::text;
+SELECT (-1<<15)::int2::text;
diff --git a/src/test/regress/sql/int4.sql b/src/test/regress/sql/int4.sql
index 5212c68..39bfec1 100644
--- a/src/test/regress/sql/int4.sql
+++ b/src/test/regress/sql/int4.sql
@@ -1,7 +1,5 @@
--
-- INT4
--- WARNING: int4 operators never check for over/underflow!
--- Some of these answers are consequently numerically incorrect.
--
CREATE TABLE INT4_TBL(f1 int4);
@@ -125,3 +123,7 @@ SELECT 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 AS ten;
SELECT 2 + 2 / 2 AS three;
SELECT (2 + 2) / 2 AS two;
+
+-- corner cases
+SELECT (1<<31-1)::int4::text;
+SELECT (1<<31)::int4::text;
diff --git a/src/test/regress/sql/int8.sql b/src/test/regress/sql/int8.sql
index 648563c..7fff03c 100644
--- a/src/test/regress/sql/int8.sql
+++ b/src/test/regress/sql/int8.sql
@@ -190,3 +190,7 @@ SELECT q1, q1 << 2 AS "shl", q1 >> 3 AS "shr" FROM INT8_TBL;
SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8);
SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8, 0);
SELECT * FROM generate_series('+4567890123456789'::int8, '+4567890123456799'::int8, 2);
+
+-- corner cases
+SELECT (1<<63-1)::int8::text;
+SELECT (1<<63)::int8::text;
--
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