From 5cb0e335976befdcedd069c59dd3858fb3e649b3 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Wed, 21 Nov 2012 15:53:35 +0200
Subject: [PATCH] Speed up operations on numeric, mostly by avoiding palloc()
overhead.
In many functions, a NumericVar was initialized from an input Numeric, to be
passed as input to a calculation function. When the NumericVar is not
modified, the digits array of the NumericVar can point directly to the digits
array in the original Numeric, and we can avoid a palloc() and memcpy(). Add
init_var_from_num() function to initialize a var like that.
Remove dscale argument from get_str_from_var(), as all the callers just
passed the dscale of the variable. That means that the rounding it used to
do was not actually necessary, and get_str_from_var() no longer scribbles on
its input. That makes it safer in general, and allows us to use the new
init_var_from_num() function in e.g numeric_out().
Also modified numericvar_to_int8() to no scribble on its input either. It
creates a temporary copy to avoid that. To compensate, the callers no longer
need to create a temporary copy, so the net # of pallocs is the same, but this
is nicer.
In the passing, use a constant for the number 10 in get_str_from_var_sci(),
when calculating 10^exponent. Saves a palloc() and some cycles to convert
integer 10 to numeric.
Original patch by Kyotaro HORIGUCHI, with further changes by me. Reviewed
by Pavel Stehule.
---
src/backend/utils/adt/numeric.c | 259 +++++++++++++-------------------
1 file changed, 104 insertions(+), 155 deletions(-)
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 68c1f1de3b7..b408df7faf4 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -276,6 +276,16 @@ static NumericDigit const_two_data[1] = {2};
static NumericVar const_two =
{1, 0, NUMERIC_POS, 0, NULL, const_two_data};
+#if DEC_DIGITS == 4 || DEC_DIGITS == 2
+static NumericDigit const_ten_data[1] = {10};
+static NumericVar const_ten =
+{1, 0, NUMERIC_POS, 0, NULL, const_ten_data};
+#elif DEC_DIGITS == 1
+static NumericDigit const_ten_data[1] = {1};
+static NumericVar const_ten =
+{1, 1, NUMERIC_POS, 0, NULL, const_ten_data};
+#endif
+
#if DEC_DIGITS == 4
static NumericDigit const_zero_point_five_data[1] = {5000};
#elif DEC_DIGITS == 2
@@ -367,8 +377,9 @@ static void zero_var(NumericVar *var);
static const char *set_var_from_str(const char *str, const char *cp,
NumericVar *dest);
static void set_var_from_num(Numeric value, NumericVar *dest);
+static void init_var_from_num(Numeric num, NumericVar *dest);
static void set_var_from_var(NumericVar *value, NumericVar *dest);
-static char *get_str_from_var(NumericVar *var, int dscale);
+static char *get_str_from_var(NumericVar *var);
static char *get_str_from_var_sci(NumericVar *var, int rscale);
static Numeric make_result(NumericVar *var);
@@ -533,18 +544,10 @@ numeric_out(PG_FUNCTION_ARGS)
/*
* Get the number in the variable format.
- *
- * Even if we didn't need to change format, we'd still need to copy the
- * value to have a modifiable copy for rounding. set_var_from_num() also
- * guarantees there is extra digit space in case we produce a carry out
- * from rounding.
*/
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
- str = get_str_from_var(&x, x.dscale);
-
- free_var(&x);
+ str = get_str_from_var(&x);
PG_RETURN_CSTRING(str);
}
@@ -616,12 +619,10 @@ numeric_out_sci(Numeric num, int scale)
if (NUMERIC_IS_NAN(num))
return pstrdup("NaN");
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
str = get_str_from_var_sci(&x, scale);
- free_var(&x);
return str;
}
@@ -695,8 +696,7 @@ numeric_send(PG_FUNCTION_ARGS)
StringInfoData buf;
int i;
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
pq_begintypsend(&buf);
@@ -707,8 +707,6 @@ numeric_send(PG_FUNCTION_ARGS)
for (i = 0; i < x.ndigits; i++)
pq_sendint(&buf, x.digits[i], sizeof(NumericDigit));
- free_var(&x);
-
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
@@ -1150,9 +1148,7 @@ numeric_ceil(PG_FUNCTION_ARGS)
if (NUMERIC_IS_NAN(num))
PG_RETURN_NUMERIC(make_result(&const_nan));
- init_var(&result);
-
- set_var_from_num(num, &result);
+ init_var_from_num(num, &result);
ceil_var(&result, &result);
res = make_result(&result);
@@ -1177,9 +1173,7 @@ numeric_floor(PG_FUNCTION_ARGS)
if (NUMERIC_IS_NAN(num))
PG_RETURN_NUMERIC(make_result(&const_nan));
- init_var(&result);
-
- set_var_from_num(num, &result);
+ init_var_from_num(num, &result);
floor_var(&result, &result);
res = make_result(&result);
@@ -1282,13 +1276,9 @@ compute_bucket(Numeric operand, Numeric bound1, Numeric bound2,
NumericVar bound2_var;
NumericVar operand_var;
- init_var(&bound1_var);
- init_var(&bound2_var);
- init_var(&operand_var);
-
- set_var_from_num(bound1, &bound1_var);
- set_var_from_num(bound2, &bound2_var);
- set_var_from_num(operand, &operand_var);
+ init_var_from_num(bound1, &bound1_var);
+ init_var_from_num(bound2, &bound2_var);
+ init_var_from_num(operand, &operand_var);
if (cmp_var(&bound1_var, &bound2_var) < 0)
{
@@ -1573,19 +1563,14 @@ numeric_add(PG_FUNCTION_ARGS)
/*
* Unpack the values, let add_var() compute the result and return it.
*/
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
-
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
+ init_var(&result);
add_var(&arg1, &arg2, &result);
res = make_result(&result);
- free_var(&arg1);
- free_var(&arg2);
free_var(&result);
PG_RETURN_NUMERIC(res);
@@ -1616,19 +1601,14 @@ numeric_sub(PG_FUNCTION_ARGS)
/*
* Unpack the values, let sub_var() compute the result and return it.
*/
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
-
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
+ init_var(&result);
sub_var(&arg1, &arg2, &result);
res = make_result(&result);
- free_var(&arg1);
- free_var(&arg2);
free_var(&result);
PG_RETURN_NUMERIC(res);
@@ -1663,19 +1643,14 @@ numeric_mul(PG_FUNCTION_ARGS)
* we request exact representation for the product (rscale = sum(dscale of
* arg1, dscale of arg2)).
*/
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
-
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
+ init_var(&result);
mul_var(&arg1, &arg2, &result, arg1.dscale + arg2.dscale);
res = make_result(&result);
- free_var(&arg1);
- free_var(&arg2);
free_var(&result);
PG_RETURN_NUMERIC(res);
@@ -1707,12 +1682,10 @@ numeric_div(PG_FUNCTION_ARGS)
/*
* Unpack the arguments
*/
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var(&result);
/*
* Select scale for division result
@@ -1726,8 +1699,6 @@ numeric_div(PG_FUNCTION_ARGS)
res = make_result(&result);
- free_var(&arg1);
- free_var(&arg2);
free_var(&result);
PG_RETURN_NUMERIC(res);
@@ -1758,12 +1729,10 @@ numeric_div_trunc(PG_FUNCTION_ARGS)
/*
* Unpack the arguments
*/
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var(&result);
/*
* Do the divide and return the result
@@ -1772,8 +1741,6 @@ numeric_div_trunc(PG_FUNCTION_ARGS)
res = make_result(&result);
- free_var(&arg1);
- free_var(&arg2);
free_var(&result);
PG_RETURN_NUMERIC(res);
@@ -1798,20 +1765,16 @@ numeric_mod(PG_FUNCTION_ARGS)
if (NUMERIC_IS_NAN(num1) || NUMERIC_IS_NAN(num2))
PG_RETURN_NUMERIC(make_result(&const_nan));
- init_var(&arg1);
- init_var(&arg2);
- init_var(&result);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
+ init_var(&result);
mod_var(&arg1, &arg2, &result);
res = make_result(&result);
free_var(&result);
- free_var(&arg2);
- free_var(&arg1);
PG_RETURN_NUMERIC(res);
}
@@ -1838,9 +1801,7 @@ numeric_inc(PG_FUNCTION_ARGS)
/*
* Compute the result and return it
*/
- init_var(&arg);
-
- set_var_from_num(num, &arg);
+ init_var_from_num(num, &arg);
add_var(&arg, &const_one, &arg);
@@ -1977,10 +1938,9 @@ numeric_sqrt(PG_FUNCTION_ARGS)
* to give at least NUMERIC_MIN_SIG_DIGITS significant digits; but in any
* case not less than the input's dscale.
*/
- init_var(&arg);
- init_var(&result);
+ init_var_from_num(num, &arg);
- set_var_from_num(num, &arg);
+ init_var(&result);
/* Assume the input was normalized, so arg.weight is accurate */
sweight = (arg.weight + 1) * DEC_DIGITS / 2 - 1;
@@ -1998,7 +1958,6 @@ numeric_sqrt(PG_FUNCTION_ARGS)
res = make_result(&result);
free_var(&result);
- free_var(&arg);
PG_RETURN_NUMERIC(res);
}
@@ -2030,10 +1989,9 @@ numeric_exp(PG_FUNCTION_ARGS)
* to give at least NUMERIC_MIN_SIG_DIGITS significant digits; but in any
* case not less than the input's dscale.
*/
- init_var(&arg);
- init_var(&result);
+ init_var_from_num(num, &arg);
- set_var_from_num(num, &arg);
+ init_var(&result);
/* convert input to float8, ignoring overflow */
val = numericvar_to_double_no_overflow(&arg);
@@ -2061,7 +2019,6 @@ numeric_exp(PG_FUNCTION_ARGS)
res = make_result(&result);
free_var(&result);
- free_var(&arg);
PG_RETURN_NUMERIC(res);
}
@@ -2088,11 +2045,9 @@ numeric_ln(PG_FUNCTION_ARGS)
if (NUMERIC_IS_NAN(num))
PG_RETURN_NUMERIC(make_result(&const_nan));
- init_var(&arg);
+ init_var_from_num(num, &arg);
init_var(&result);
- set_var_from_num(num, &arg);
-
/* Approx decimal digits before decimal point */
dec_digits = (arg.weight + 1) * DEC_DIGITS;
@@ -2112,7 +2067,6 @@ numeric_ln(PG_FUNCTION_ARGS)
res = make_result(&result);
free_var(&result);
- free_var(&arg);
PG_RETURN_NUMERIC(res);
}
@@ -2142,13 +2096,10 @@ numeric_log(PG_FUNCTION_ARGS)
/*
* Initialize things
*/
- init_var(&arg1);
- init_var(&arg2);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
init_var(&result);
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
-
/*
* Call log_var() to compute and return the result; note it handles scale
* selection itself.
@@ -2158,8 +2109,6 @@ numeric_log(PG_FUNCTION_ARGS)
res = make_result(&result);
free_var(&result);
- free_var(&arg2);
- free_var(&arg1);
PG_RETURN_NUMERIC(res);
}
@@ -2190,15 +2139,12 @@ numeric_power(PG_FUNCTION_ARGS)
/*
* Initialize things
*/
- init_var(&arg1);
- init_var(&arg2);
init_var(&arg2_trunc);
init_var(&result);
+ init_var_from_num(num1, &arg1);
+ init_var_from_num(num2, &arg2);
- set_var_from_num(num1, &arg1);
- set_var_from_num(num2, &arg2);
set_var_from_var(&arg2, &arg2_trunc);
-
trunc_var(&arg2_trunc, 0);
/*
@@ -2227,9 +2173,7 @@ numeric_power(PG_FUNCTION_ARGS)
res = make_result(&result);
free_var(&result);
- free_var(&arg2);
free_var(&arg2_trunc);
- free_var(&arg1);
PG_RETURN_NUMERIC(res);
}
@@ -2276,10 +2220,8 @@ numeric_int4(PG_FUNCTION_ARGS)
errmsg("cannot convert NaN to integer")));
/* Convert to variable format, then convert to int4 */
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
result = numericvar_to_int4(&x);
- free_var(&x);
PG_RETURN_INT32(result);
}
@@ -2344,16 +2286,13 @@ numeric_int8(PG_FUNCTION_ARGS)
errmsg("cannot convert NaN to bigint")));
/* Convert to variable format and thence to int8 */
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
if (!numericvar_to_int8(&x, &result))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("bigint out of range")));
- free_var(&x);
-
PG_RETURN_INT64(result);
}
@@ -2392,16 +2331,13 @@ numeric_int2(PG_FUNCTION_ARGS)
errmsg("cannot convert NaN to smallint")));
/* Convert to variable format and thence to int8 */
- init_var(&x);
- set_var_from_num(num, &x);
+ init_var_from_num(num, &x);
if (!numericvar_to_int8(&x, &val))
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("smallint out of range")));
- free_var(&x);
-
/* Down-convert to int2 */
result = (int16) val;
@@ -2763,8 +2699,7 @@ numeric_stddev_internal(ArrayType *transarray,
if (NUMERIC_IS_NAN(N) || NUMERIC_IS_NAN(sumX) || NUMERIC_IS_NAN(sumX2))
return make_result(&const_nan);
- init_var(&vN);
- set_var_from_num(N, &vN);
+ init_var_from_num(N, &vN);
/*
* Sample stddev and variance are undefined when N <= 1; population stddev
@@ -2777,7 +2712,6 @@ numeric_stddev_internal(ArrayType *transarray,
if (cmp_var(&vN, comp) <= 0)
{
- free_var(&vN);
*is_null = true;
return NULL;
}
@@ -2785,10 +2719,8 @@ numeric_stddev_internal(ArrayType *transarray,
init_var(&vNminus1);
sub_var(&vN, &const_one, &vNminus1);
- init_var(&vsumX);
- set_var_from_num(sumX, &vsumX);
- init_var(&vsumX2);
- set_var_from_num(sumX2, &vsumX2);
+ init_var_from_num(sumX, &vsumX);
+ init_var_from_num(sumX2, &vsumX2);
/* compute rscale for mul_var calls */
rscale = vsumX.dscale * 2;
@@ -2816,7 +2748,6 @@ numeric_stddev_internal(ArrayType *transarray,
res = make_result(&vsumX);
}
- free_var(&vN);
free_var(&vNminus1);
free_var(&vsumX);
free_var(&vsumX2);
@@ -3449,6 +3380,32 @@ set_var_from_num(Numeric num, NumericVar *dest)
}
+/*
+ * init_var_from_num() -
+ *
+ * Initialize a variable from packed db format. The digits array is not
+ * copied, which saves some cycles when the resulting var is not modified.
+ * Also, there's no need to call free_var(), as long as you don't assign any
+ * other value to it (with set_var_* functions, or by using the var as the
+ * destination of a function like add_var())
+ *
+ * CAUTION: Do not modify the digits buffer of a var initialized with this
+ * function, e.g by calling round_var() or trunc_var(), as the changes will
+ * propagate to the original Numeric! It's OK to use it as the destination
+ * argument of one of the calculational functions, though.
+ */
+static void
+init_var_from_num(Numeric num, NumericVar *dest)
+{
+ dest->ndigits = NUMERIC_NDIGITS(num);
+ dest->weight = NUMERIC_WEIGHT(num);
+ dest->sign = NUMERIC_SIGN(num);
+ dest->dscale = NUMERIC_DSCALE(num);
+ dest->digits = NUMERIC_DIGITS(num);
+ dest->buf = NULL; /* digits array is not palloc'd */
+}
+
+
/*
* set_var_from_var() -
*
@@ -3475,12 +3432,13 @@ set_var_from_var(NumericVar *value, NumericVar *dest)
* get_str_from_var() -
*
* Convert a var to text representation (guts of numeric_out).
- * CAUTION: var's contents may be modified by rounding!
+ * The var is displayed to the number of digits indicated by its dscale.
* Returns a palloc'd string.
*/
static char *
-get_str_from_var(NumericVar *var, int dscale)
+get_str_from_var(NumericVar *var)
{
+ int dscale;
char *str;
char *cp;
char *endcp;
@@ -3492,13 +3450,7 @@ get_str_from_var(NumericVar *var, int dscale)
NumericDigit d1;
#endif
- if (dscale < 0)
- dscale = 0;
-
- /*
- * Check if we must round up before printing the value and do so.
- */
- round_var(var, dscale);
+ dscale = var->dscale;
/*
* Allocate space for the result.
@@ -3634,8 +3586,6 @@ get_str_from_var(NumericVar *var, int dscale)
* rscale is the number of decimal digits desired after the decimal point in
* the output, negative values will be treated as meaning zero.
*
- * CAUTION: var's contents may be modified by rounding!
- *
* Returns a palloc'd string.
*/
static char *
@@ -3694,10 +3644,9 @@ get_str_from_var_sci(NumericVar *var, int rscale)
init_var(&denominator);
init_var(&significand);
- int8_to_numericvar((int64) 10, &denominator);
- power_var_int(&denominator, exponent, &denominator, denom_scale);
+ power_var_int(&const_ten, exponent, &denominator, denom_scale);
div_var(var, &denominator, &significand, rscale, true);
- sig_out = get_str_from_var(&significand, rscale);
+ sig_out = get_str_from_var(&significand);
free_var(&denominator);
free_var(&significand);
@@ -3886,8 +3835,6 @@ apply_typmod(NumericVar *var, int32 typmod)
* Convert numeric to int8, rounding if needed.
*
* If overflow, return FALSE (no error is raised). Return TRUE if okay.
- *
- * CAUTION: var's contents may be modified by rounding!
*/
static bool
numericvar_to_int8(NumericVar *var, int64 *result)
@@ -3899,16 +3846,20 @@ numericvar_to_int8(NumericVar *var, int64 *result)
int64 val,
oldval;
bool neg;
+ NumericVar rounded;
/* Round to nearest integer */
- round_var(var, 0);
+ init_var(&rounded);
+ set_var_from_var(var, &rounded);
+ round_var(&rounded, 0);
/* Check for zero input */
- strip_var(var);
- ndigits = var->ndigits;
+ strip_var(&rounded);
+ ndigits = rounded.ndigits;
if (ndigits == 0)
{
*result = 0;
+ free_var(&rounded);
return true;
}
@@ -3916,12 +3867,12 @@ numericvar_to_int8(NumericVar *var, int64 *result)
* For input like 10000000000, we must treat stripped digits as real. So
* the loop assumes there are weight+1 digits before the decimal point.
*/
- weight = var->weight;
+ weight = rounded.weight;
Assert(weight >= 0 && ndigits <= weight + 1);
/* Construct the result */
- digits = var->digits;
- neg = (var->sign == NUMERIC_NEG);
+ digits = rounded.digits;
+ neg = (rounded.sign == NUMERIC_NEG);
val = digits[0];
for (i = 1; i <= weight; i++)
{
@@ -3940,10 +3891,15 @@ numericvar_to_int8(NumericVar *var, int64 *result)
if ((val / NBASE) != oldval) /* possible overflow? */
{
if (!neg || (-val) != val || val == 0 || oldval < 0)
+ {
+ free_var(&rounded);
return false;
+ }
}
}
+ free_var(&rounded);
+
*result = neg ? -val : val;
return true;
}
@@ -4030,7 +3986,7 @@ numericvar_to_double_no_overflow(NumericVar *var)
double val;
char *endptr;
- tmp = get_str_from_var(var, var->dscale);
+ tmp = get_str_from_var(var);
/* unlike float8in, we ignore ERANGE from strtod */
val = strtod(tmp, &endptr);
@@ -5597,13 +5553,9 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
if (exp->ndigits == 0 || exp->ndigits <= exp->weight + 1)
{
/* exact integer, but does it fit in int? */
- NumericVar x;
int64 expval64;
- /* must copy because numericvar_to_int8() scribbles on input */
- init_var(&x);
- set_var_from_var(exp, &x);
- if (numericvar_to_int8(&x, &expval64))
+ if (numericvar_to_int8(exp, &expval64))
{
int expval = (int) expval64;
@@ -5617,12 +5569,9 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
rscale = Min(rscale, NUMERIC_MAX_DISPLAY_SCALE);
power_var_int(base, expval, result, rscale);
-
- free_var(&x);
return;
}
}
- free_var(&x);
}
/*
--
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