Re:

LMdlCqL> Hi, just to report a strange behaviour in PostgreSQL v6.3.2, Linux
LMdlCqL> 2.0.34.

LMdlCqL> I do this:

hjk=>> alter table control_veh add column fecalta date;
LMdlCqL> ADD

LMdlCqL> then that:

hjk=>> update control_veh set fecalta='01-01-1800' where plact='440JAS';
LMdlCqL> ERROR:  Relation control_veh does not have attribute fecalta

LMdlCqL> later this:

hjk=>> \d control_veh

LMdlCqL> Table    = control_veh
LMdlCqL> +----------------------------------+----------------------------------+-------+
LMdlCqL> |              Field               |              Type                | Length|
LMdlCqL> +----------------------------------+----------------------------------+-------+
LMdlCqL> | paterno                          | char()                           |    25 |
LMdlCqL> ...many fields...
LMdlCqL> | ultpago                          | char()                           |     2 |
LMdlCqL> | fecalta                          | date                             |     4 |
LMdlCqL> +----------------------------------+----------------------------------+-------+

LMdlCqL> this again:

hjk=>> update control_veh set fecalta='01-01-1800' where plact='440JAS';
LMdlCqL> ERROR:  Relation control_veh does not have attribute fecalta

LMdlCqL> desperate this:

hjk=>> vacuum control_veh;
LMdlCqL> VACUUM
hjk=>> alter table control_veh add column fecalta date;
LMdlCqL> ERROR:  PerformAddAttribute: attribute "fecalta" already exists in class "control_veh"
hjk=>>

LMdlCqL> then again:

hjk=>> update control_veh set fecalta='01-01-1800' where plact='440JAS';
LMdlCqL> UPDATE 1
hjk=>> select * from control_veh where plact='440JAS';

LMdlCqL> and voilà, it's complete. Isn't it strange?

This is an pgsql's old bug already reported by me.
The problem is that you can't reproduce this behavior all the time.
I have this bug also, but it appears only sometimes. It isn't danger
only disquieting. ;-)

Buena suerte!
   Jose'