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Fix NUMERIC modulus to properly truncate division in computation.

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Division rounding was causing incorrect results.  Test case:

	test=> SELECT 12345678901234567890 % 123;
	 ?column?
	----------
	       78
	(1 row)

Was returning -45.
This commit is contained in:
Bruce Momjian
2005-06-04 14:12:50 +00:00
parent a76606454c
commit 1bc9235224
1 changed files with 22 additions and 19 deletions
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41
src/backend/utils/adt/numeric.c
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@ -14,7 +14,7 @@
* Copyright (c) 1998-2005, PostgreSQL Global Development Group * Copyright (c) 1998-2005, PostgreSQL Global Development Group
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.83 2005/04/06 23:56:07 neilc Exp $ * $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.84 2005/06/04 14:12:50 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -265,7 +265,7 @@ static void sub_var(NumericVar *var1, NumericVar *var2, NumericVar *result);
static void mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result, static void mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
int rscale); int rscale);
static void div_var(NumericVar *var1, NumericVar *var2, NumericVar *result, static void div_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
int rscale); int rscale, bool round);
static int select_div_scale(NumericVar *var1, NumericVar *var2); static int select_div_scale(NumericVar *var1, NumericVar *var2);
static void mod_var(NumericVar *var1, NumericVar *var2, NumericVar *result); static void mod_var(NumericVar *var1, NumericVar *var2, NumericVar *result);
static void ceil_var(NumericVar *var, NumericVar *result); static void ceil_var(NumericVar *var, NumericVar *result);
@ -906,14 +906,14 @@ compute_bucket(Numeric operand, Numeric bound1, Numeric bound2,
sub_var(&operand_var, &bound1_var, &operand_var); sub_var(&operand_var, &bound1_var, &operand_var);
sub_var(&bound2_var, &bound1_var, &bound2_var); sub_var(&bound2_var, &bound1_var, &bound2_var);
div_var(&operand_var, &bound2_var, result_var, div_var(&operand_var, &bound2_var, result_var,
select_div_scale(&operand_var, &bound2_var)); select_div_scale(&operand_var, &bound2_var), true);
} }
else else
{ {
sub_var(&bound1_var, &operand_var, &operand_var); sub_var(&bound1_var, &operand_var, &operand_var);
sub_var(&bound1_var, &bound2_var, &bound1_var); sub_var(&bound1_var, &bound2_var, &bound1_var);
div_var(&operand_var, &bound1_var, result_var, div_var(&operand_var, &bound1_var, result_var,
select_div_scale(&operand_var, &bound1_var)); select_div_scale(&operand_var, &bound1_var), true);
} }
mul_var(result_var, count_var, result_var, mul_var(result_var, count_var, result_var,
@ -1266,7 +1266,7 @@ numeric_div(PG_FUNCTION_ARGS)
/* /*
* Do the divide and return the result * Do the divide and return the result
*/ */
div_var(&arg1, &arg2, &result, rscale); div_var(&arg1, &arg2, &result, rscale, true);
res = make_result(&result); res = make_result(&result);
@ -2246,7 +2246,7 @@ numeric_variance(PG_FUNCTION_ARGS)
{ {
mul_var(&vN, &vNminus1, &vNminus1, 0); /* N * (N - 1) */ mul_var(&vN, &vNminus1, &vNminus1, 0); /* N * (N - 1) */
rscale = select_div_scale(&vsumX2, &vNminus1); rscale = select_div_scale(&vsumX2, &vNminus1);
div_var(&vsumX2, &vNminus1, &vsumX, rscale); /* variance */ div_var(&vsumX2, &vNminus1, &vsumX, rscale, true); /* variance */
res = make_result(&vsumX); res = make_result(&vsumX);
} }
@ -2322,7 +2322,7 @@ numeric_stddev(PG_FUNCTION_ARGS)
{ {
mul_var(&vN, &vNminus1, &vNminus1, 0); /* N * (N - 1) */ mul_var(&vN, &vNminus1, &vNminus1, 0); /* N * (N - 1) */
rscale = select_div_scale(&vsumX2, &vNminus1); rscale = select_div_scale(&vsumX2, &vNminus1);
div_var(&vsumX2, &vNminus1, &vsumX, rscale); /* variance */ div_var(&vsumX2, &vNminus1, &vsumX, rscale, true); /* variance */
sqrt_var(&vsumX, &vsumX, rscale); /* stddev */ sqrt_var(&vsumX, &vsumX, rscale); /* stddev */
res = make_result(&vsumX); res = make_result(&vsumX);
@ -3840,7 +3840,7 @@ mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
*/ */
static void static void
div_var(NumericVar *var1, NumericVar *var2, NumericVar *result, div_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
int rscale) int rscale, bool round)
{ {
int div_ndigits; int div_ndigits;
int res_sign; int res_sign;
@ -4079,8 +4079,11 @@ div_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
result->sign = res_sign; result->sign = res_sign;
/* Round to target rscale (and set result->dscale) */ /* Round to target rscale (and set result->dscale) */
round_var(result, rscale); if (round)
round_var(result, rscale);
else
trunc_var(result, rscale);
/* Strip leading and trailing zeroes */ /* Strip leading and trailing zeroes */
strip_var(result); strip_var(result);
} }
@ -4178,7 +4181,7 @@ mod_var(NumericVar *var1, NumericVar *var2, NumericVar *result)
*/ */
rscale = select_div_scale(var1, var2); rscale = select_div_scale(var1, var2);
div_var(var1, var2, &tmp, rscale); div_var(var1, var2, &tmp, rscale, false);
trunc_var(&tmp, 0); trunc_var(&tmp, 0);
@ -4294,7 +4297,7 @@ sqrt_var(NumericVar *arg, NumericVar *result, int rscale)
for (;;) for (;;)
{ {
div_var(&tmp_arg, result, &tmp_val, local_rscale); div_var(&tmp_arg, result, &tmp_val, local_rscale, true);
add_var(result, &tmp_val, result); add_var(result, &tmp_val, result);
mul_var(result, &const_zero_point_five, result, local_rscale); mul_var(result, &const_zero_point_five, result, local_rscale);
@ -4384,7 +4387,7 @@ exp_var(NumericVar *arg, NumericVar *result, int rscale)
/* Compensate for input sign, and round to requested rscale */ /* Compensate for input sign, and round to requested rscale */
if (xneg) if (xneg)
div_var(&const_one, result, result, rscale); div_var(&const_one, result, result, rscale, true);
else else
round_var(result, rscale); round_var(result, rscale);
@ -4450,7 +4453,7 @@ exp_var_internal(NumericVar *arg, NumericVar *result, int rscale)
add_var(&ni, &const_one, &ni); add_var(&ni, &const_one, &ni);
mul_var(&xpow, &x, &xpow, local_rscale); mul_var(&xpow, &x, &xpow, local_rscale);
mul_var(&ifac, &ni, &ifac, 0); mul_var(&ifac, &ni, &ifac, 0);
div_var(&xpow, &ifac, &elem, local_rscale); div_var(&xpow, &ifac, &elem, local_rscale, true);
if (elem.ndigits == 0) if (elem.ndigits == 0)
break; break;
@ -4534,7 +4537,7 @@ ln_var(NumericVar *arg, NumericVar *result, int rscale)
*/ */
sub_var(&x, &const_one, result); sub_var(&x, &const_one, result);
add_var(&x, &const_one, &elem); add_var(&x, &const_one, &elem);
div_var(result, &elem, result, local_rscale); div_var(result, &elem, result, local_rscale, true);
set_var_from_var(result, &xx); set_var_from_var(result, &xx);
mul_var(result, result, &x, local_rscale); mul_var(result, result, &x, local_rscale);
@ -4544,7 +4547,7 @@ ln_var(NumericVar *arg, NumericVar *result, int rscale)
{ {
add_var(&ni, &const_two, &ni); add_var(&ni, &const_two, &ni);
mul_var(&xx, &x, &xx, local_rscale); mul_var(&xx, &x, &xx, local_rscale);
div_var(&xx, &ni, &elem, local_rscale); div_var(&xx, &ni, &elem, local_rscale, true);
if (elem.ndigits == 0) if (elem.ndigits == 0)
break; break;
@ -4614,7 +4617,7 @@ log_var(NumericVar *base, NumericVar *num, NumericVar *result)
/* Select scale for division result */ /* Select scale for division result */
rscale = select_div_scale(&ln_num, &ln_base); rscale = select_div_scale(&ln_num, &ln_base);
div_var(&ln_num, &ln_base, result, rscale); div_var(&ln_num, &ln_base, result, rscale, true);
free_var(&ln_num); free_var(&ln_num);
free_var(&ln_base); free_var(&ln_base);
@ -4752,7 +4755,7 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
round_var(result, rscale); round_var(result, rscale);
return; return;
case -1: case -1:
div_var(&const_one, base, result, rscale); div_var(&const_one, base, result, rscale, true);
return; return;
case 2: case 2:
mul_var(base, base, result, rscale); mul_var(base, base, result, rscale);
@ -4790,7 +4793,7 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
/* Compensate for input sign, and round to requested rscale */ /* Compensate for input sign, and round to requested rscale */
if (neg) if (neg)
div_var(&const_one, result, result, rscale); div_var(&const_one, result, result, rscale, true);
else else
round_var(result, rscale); round_var(result, rscale);
} }