diff options
Diffstat (limited to 'src/backend/utils/adt/numeric.c')
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index 834339dcff2..08c841675d8 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -3693,8 +3693,21 @@ numeric_sqrt(PG_FUNCTION_ARGS) init_var(&result); - /* Assume the input was normalized, so arg.weight is accurate */ - sweight = (arg.weight + 1) * DEC_DIGITS / 2 - 1; + /* + * Assume the input was normalized, so arg.weight is accurate. The result + * then has at least sweight = floor(arg.weight * DEC_DIGITS / 2 + 1) + * digits before the decimal point. When DEC_DIGITS is even, we can save + * a few cycles, since the division is exact and there is no need to round + * towards negative infinity. + */ +#if DEC_DIGITS == ((DEC_DIGITS / 2) * 2) + sweight = arg.weight * DEC_DIGITS / 2 + 1; +#else + if (arg.weight >= 0) + sweight = arg.weight * DEC_DIGITS / 2 + 1; + else + sweight = 1 - (1 - arg.weight * DEC_DIGITS) / 2; +#endif rscale = NUMERIC_MIN_SIG_DIGITS - sweight; rscale = Max(rscale, arg.dscale); |