Adjust power() error messages to be more descriptive.

diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
index 706a436db3809fd75fda7f24e56885238e4c033d..4d9dc20a281a495bbed01d39393ac726c1a16b6a 100644 (file)
--- a/src/backend/utils/adt/float.c
+++ b/src/backend/utils/adt/float.c
@@ -1334,11 +1334,14 @@ dpow(PG_FUNCTION_ARGS)
         * 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))
+       if (arg1 == 0 && arg2 < 0)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
-                                errmsg("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

diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 19820f6c0bc7a8e9375b854c4183a9ef1844cca8..bb8ac7e9c844bbd4f8f6ed3ff464d0f1bcd3f9a3 100644 (file)
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -1897,13 +1897,17 @@ numeric_power(PG_FUNCTION_ARGS)
         * 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))
+       if (cmp_var(&arg1, &const_zero) == 0 &&
+               cmp_var(&arg2, &const_zero) < 0)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_ARGUMENT_FOR_POWER_FUNCTION),
-                                errmsg("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