Re: Using 128-bit integers for sum, avg and statistics aggregates

Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> writes:
> On 12/31/14, 8:13 AM, Andres Freund wrote:
>> Note that the C datatype has been int32/int64 for a while now, it's just
>> the SQL datatype and the names of its support functions. Given that,
>> afaiu, we're talking about the C datatype it seems pretty clear that it
>> should be named int128.

I don't think there was any debate about calling the C typedef int128.
The question at hand was that there are some existing C functions whose
names follow the int2/int4/int8 convention, and it's not very clear what
to do with their 128-bit analogues. Having said that, I'm fine with
switching to int128 for the C names of the new functions; but it is
definitely less than consistent with what we're doing elsewhere.

> Should we start down this road with SQL too, by creating int32, 64 and 128 (if needed?), and changing docs as needed?

No. The situation is messy enough without changing our conventions at
the SQL level; that will introduce breakage into user applications,
for no very good reason because we've never had any inconsistency there.

What might be worth trying is establishing a hard-and-fast boundary
between C land and SQL land, with bitwise names in C and bytewise names
in SQL. This would mean, for example, that int4pl() would be renamed to
int32pl() so far as the C function goes, but the function's SQL name would
remain the same. That would introduce visible inconsistency between such
functions' pg_proc.proname and pg_proc.prosrc fields, but at least the
inconsistency would follow a very clear pattern. And I doubt that very
many user applications are depending on the contents of pg_proc.prosrc.

regards, tom lane