Implement width_bucket() for the float8 data type.

The implementation is somewhat ugly logic-wise, but I don't see an
easy way to make it more concise.

When writing this, I noticed that my previous implementation of
width_bucket() doesn't handle NaN correctly:

    postgres=# select width_bucket('NaN', 1, 5, 5);
     width_bucket
    --------------
                6
    (1 row)

AFAICS SQL:2003 does not define a NaN value, so it doesn't address how
width_bucket() should behave here. The patch changes width_bucket() so
that ereport(ERROR) is raised if NaN is specified for the operand or the
lower or upper bounds to width_bucket(). For float8, NaN is disallowed
for any of the floating-point inputs, and +/- infinity is disallowed
for the histogram bounds (but allowed for the operand).

Update docs and regression tests, bump the catversion.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 396bac922d..3368e2c024 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.285 2007/01/05 22:19:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.286 2007/01/16 21:41:14 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -380,6 +380,7 @@ extern Datum float84lt(PG_FUNCTION_ARGS);
 extern Datum float84le(PG_FUNCTION_ARGS);
 extern Datum float84gt(PG_FUNCTION_ARGS);
 extern Datum float84ge(PG_FUNCTION_ARGS);
+extern Datum width_bucket_float8(PG_FUNCTION_ARGS);
 
 /* dbsize.c */
 extern Datum pg_tablespace_size_oid(PG_FUNCTION_ARGS);