Re: SQL float types

Tom Lane writes:

> > float4 => real
> > float8 => double precision

> Not just on your say-so. Arguments please?

SQL:

22)REAL specifies the data type approximate numeric, with implementation-
defined precision.

23)DOUBLE PRECISION specifies the data type approximate numeric,
with implementation-defined precision that is greater than the
implementation-defined precision of REAL.

Notice that there is no "at least" here anywhere.

> In the absence of pretty compelling reasons to change, I think
> "backwards compatibility" will have to win the day on something like
> this.

The REAL data type is not even documented. I'm evidently trying to get
people to think in terms of standard types rather than the internal,
low-level sounding names, but that won't work if the standard types aren't
really standard and the internal types don't have a standard equivalent.

Actually, if you read into the release history it says:

SQL standard-compliance (the following details changes that makes
postgres95 more compliant to the SQL-92 standard):
* the following SQL types are now built-in: smallint, int(eger), float, real,
char(N), varchar(N), date and time.

The following are aliases to existing postgres types:
smallint -> int2
integer, int -> int4
float, real -> float4
char(N) and varchar(N) are implemented as truncated text types. In
addition, char(N) does blank-padding.

So if you take that as documentation then my suggestion counts as a bug
fix. :-)

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Peter Eisentraut Sernanders väg 10:115
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