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| author | Dean Rasheed <dean.a.rasheed@gmail.com> | 2021-07-10 12:46:13 +0100 |
|---|---|---|
| committer | Dean Rasheed <dean.a.rasheed@gmail.com> | 2021-07-10 12:46:13 +0100 |
| commit | f23a9b8a49af1ef89dd65399867ca21318ae6b8e (patch) | |
| tree | 41ec85c8a07112630a38226ed085d5cd3287a5b3 | |
| parent | 32d0bdbfcf2f1f024f24797eda14a250c13fa62e (diff) | |
| download | postgresql-f23a9b8a49af1ef89dd65399867ca21318ae6b8e.tar.gz postgresql-f23a9b8a49af1ef89dd65399867ca21318ae6b8e.zip | |
Fix numeric_mul() overflow due to too many digits after decimal point.
This fixes an overflow error when using the numeric * operator if the
result has more than 16383 digits after the decimal point by rounding
the result. Overflow errors should only occur if the result has too
many digits *before* the decimal point.
Discussion: https://postgr.es/m/CAEZATCUmeFWCrq2dNzZpRj5+6LfN85jYiDoqm+ucSXhb9U2TbA@mail.gmail.com
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 10 | ||||
| -rw-r--r-- | src/test/regress/expected/numeric.out | 6 | ||||
| -rw-r--r-- | src/test/regress/sql/numeric.sql | 2 |
3 files changed, 17 insertions, 1 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index 7e47aa038e0..d5d2b1cfad0 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -205,6 +205,7 @@ struct NumericData */ #define NUMERIC_DSCALE_MASK 0x3FFF +#define NUMERIC_DSCALE_MAX NUMERIC_DSCALE_MASK #define NUMERIC_SIGN(n) \ (NUMERIC_IS_SHORT(n) ? \ @@ -2549,7 +2550,11 @@ numeric_mul_opt_error(Numeric num1, Numeric num2, bool *have_error) * Unlike add_var() and sub_var(), mul_var() will round its result. In the * case of numeric_mul(), which is invoked for the * operator on numerics, * we request exact representation for the product (rscale = sum(dscale of - * arg1, dscale of arg2)). + * arg1, dscale of arg2)). If the exact result has more digits after the + * decimal point than can be stored in a numeric, we round it. Rounding + * after computing the exact result ensures that the final result is + * correctly rounded (rounding in mul_var() using a truncated product + * would not guarantee this). */ init_var_from_num(num1, &arg1); init_var_from_num(num2, &arg2); @@ -2557,6 +2562,9 @@ numeric_mul_opt_error(Numeric num1, Numeric num2, bool *have_error) init_var(&result); mul_var(&arg1, &arg2, &result, arg1.dscale + arg2.dscale); + if (result.dscale > NUMERIC_DSCALE_MAX) + round_var(&result, NUMERIC_DSCALE_MAX); + res = make_result_opt_error(&result, have_error); free_var(&result); diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out index c05bf7b8e6a..dbb9e4ad1f1 100644 --- a/src/test/regress/expected/numeric.out +++ b/src/test/regress/expected/numeric.out @@ -1498,6 +1498,12 @@ select 4769999999999999999999999999999999999999999999999999999999999999999999999 47699999999999999999999999999999999999999999999999999999999999999999999999999999999999985230000000000000000000000000000000000000000000000000000000000000000000000000000000000001 (1 row) +select trim_scale((0.1 - 2e-16383) * (0.1 - 3e-16383)); + trim_scale +------------ + 0.01 +(1 row) + -- -- Test some corner cases for division -- diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql index 6fa8d3fcc0b..3d03862b646 100644 --- a/src/test/regress/sql/numeric.sql +++ b/src/test/regress/sql/numeric.sql @@ -864,6 +864,8 @@ select 4770999999999999999999999999999999999999999999999999999999999999999999999 select 4769999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999; +select trim_scale((0.1 - 2e-16383) * (0.1 - 3e-16383)); + -- -- Test some corner cases for division -- |