Re: pgsql: Have numeric 0 ^ 4.3 return 1, rather than an error, and have 0 ^ - Mailing list pgsql-committers

Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> >> b) If VB is 0 (zero) and VE is negative, then an exception condition is
> >> raised: data exception � invalid argument for power function.
>
> > Well, this indicates we shouldn't return "zero raised to a negative
> > power is undefined", but rather the power error we are giving now, or
> > are you saying we should return the "power" error code but an error
> > message mentioning zero?
>
> The spec says what the SQLSTATE code should be.   We have always felt
> free to word the message text more specifically than that, though.

OK, error wording updated, attached, and applied.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: src/backend/utils/adt/float.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/float.c,v
retrieving revision 1.156
diff -c -c -r1.156 float.c
*** src/backend/utils/adt/float.c    9 May 2008 15:36:06 -0000    1.156
--- src/backend/utils/adt/float.c    9 May 2008 21:29:37 -0000
***************
*** 1334,1344 ****
       * certain error conditions.  Specifically, we don't return a divide-by-zero
       * error code for 0 ^ -1.
       */
!     if ((arg1 == 0 && arg2 < 0) ||
!         (arg1 < 0 && floor(arg2) != arg2))
          ereport(ERROR,
                  (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("invalid argument for power function")));

      /*
       * pow() sets errno only on some platforms, depending on whether it
--- 1334,1347 ----
       * certain error conditions.  Specifically, we don't return a divide-by-zero
       * error code for 0 ^ -1.
       */
!     if (arg1 == 0 && arg2 < 0)
          ereport(ERROR,
                  (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("zero raised to a negative power is undefined")));
!     if (arg1 < 0 && floor(arg2) != arg2)
!         ereport(ERROR,
!                 (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("a negative number raised to a non-integer power yields a complex result")));

      /*
       * pow() sets errno only on some platforms, depending on whether it
Index: src/backend/utils/adt/numeric.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v
retrieving revision 1.113
diff -c -c -r1.113 numeric.c
*** src/backend/utils/adt/numeric.c    9 May 2008 15:36:06 -0000    1.113
--- src/backend/utils/adt/numeric.c    9 May 2008 21:29:37 -0000
***************
*** 1897,1909 ****
       * certain error conditions.  Specifically, we don't return a divide-by-zero
       * error code for 0 ^ -1.
       */
!     if ((cmp_var(&arg1, &const_zero) == 0 &&
!          cmp_var(&arg2, &const_zero) < 0) ||
!         (cmp_var(&arg1, &const_zero) < 0 &&
!          cmp_var(&arg2, &arg2_trunc) != 0))
          ereport(ERROR,
                  (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("invalid argument for power function")));

      /*
       * Call power_var() to compute and return the result; note it handles
--- 1897,1913 ----
       * certain error conditions.  Specifically, we don't return a divide-by-zero
       * error code for 0 ^ -1.
       */
!     if (cmp_var(&arg1, &const_zero) == 0 &&
!         cmp_var(&arg2, &const_zero) < 0)
          ereport(ERROR,
                  (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("zero raised to a negative power is undefined")));
!
!     if (cmp_var(&arg1, &const_zero) < 0 &&
!         cmp_var(&arg2, &arg2_trunc) != 0)
!         ereport(ERROR,
!                 (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
!                  errmsg("a negative number raised to a non-integer power yields a complex result")));

      /*
       * Call power_var() to compute and return the result; note it handles