On 01/14/2011 09:51 PM, Tom Lane wrote:
Stephen Frost<sfr...@snowman.net> writes:
* Tom Lane (t...@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
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