On 01/14/2011 09:51 PM, Tom Lane wrote:
> Stephen Frost<sfrost@snowman.net> writes:
>> * Tom Lane (tgl@sss.pgh.pa.us) wrote:
>>> A user-settable column list seems pretty on-target
>>> for solving those problems to me.
>> I'm looking into implementing this.
>> An interesting initial question is- should the users be able to control
>> the *order* of the columns? My gut feeling, if we're giving them a GUC
>> that's a list of fields, is 'yes', but I'm happy to listen to other
>> thoughts.
> Yeah, I was just thinking about that in connection with the suggestion
> of using a bitmap as the pre-parsed representation (which would more or
> less force adoption of the fixed-column-order approach). I really think
> we can't get away with that. Remember what Andrew pointed out upthread:
> it's important to be able to load the csvlog output directly into a
> table without any extra processing. Suppose a DBA is logging columns
> A,B,D and he later realizes that logging C would be a good thing too.
> He's going to have to ALTER TABLE ADD COLUMN to add C to his logging
> table ... and now it's at the end. This is no problem if he can set the
> GUC to be "A,B,D,C" and have the field order be honored. Otherwise he's
> got a problem.
Ok, you sold me. Until I read this I was inclined to say not, on KISS
principles.
The only thing I'd suggest extra is that we might allow "version_n_m" as
shorthand for the default table layout from the relevant version.
cheers
andrew
