Fix division-by-zero error in to_char() with 'EEEE' format. This fixes a long-standing bug when using to_char() to format a numeric value in scientific notation -- if the value's exponent is less than -NUMERIC_MAX_DISPLAY_SCALE-1 (-1001), it produced a division-by-zero error.
The reason for this error was that get_str_from_var_sci() divides its input by 10^exp, which it produced using power_var_int(). However, the underflow test in power_var_int() causes it to return zero if the result scale is too small. That's not a problem for power_var_int()'s only other caller, power_var(), since that limits the rscale to 1000, but in get_str_from_var_sci() the exponent can be much smaller, requiring a much larger rscale. Fix by introducing a new function to compute 10^exp directly, with no rscale limit. This also allows 10^exp to be computed more efficiently, without any numeric multiplication, division or rounding. Discussion: https://postgr.es/m/caezatcwhojfh4whaqgukbe8d5jnhb8ytzeml-pnrx+kctym...@mail.gmail.com Branch ------ REL_11_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/4851940a5c000b2b2504d7add13dfbd463c1c59c Modified Files -------------- src/backend/utils/adt/numeric.c | 66 ++++++++++++++++++++--------------- src/test/regress/expected/numeric.out | 33 ++++++++++++++++++ src/test/regress/sql/numeric.sql | 8 +++++ 3 files changed, 78 insertions(+), 29 deletions(-)