Thread: Unique key with nulls and copying databases across computers

Hi

I have a few questions:

1. Is there a simple way in postgresql 6.3.2 to implement a unique index on
one
field with null's allowed. So if the field is null it's ok else the value
must be unique?

2. I have copied the contents of a database ( ../data/base/name/* ) from one
computer to another computer. Is this in fact the way to copy databases?
After copying everything works except for example \dt , \di which gives the
following
error:

ERROR: cache lookup for userid 1003 failed

What does this mean?

Regards
Wim Ceulemans
Nice Software Solutions

Wim Ceulemans wrote:
>
> Hi
>
> I have a few questions:
>
> 1. Is there a simple way in postgresql 6.3.2 to implement a unique index on
> one
> field with null's allowed. So if the field is null it's ok else the value
> must be unique?

This is exactly what postgresql does!
Did you see any problems?

>
> 2. I have copied the contents of a database ( ../data/base/name/* ) from one
> computer to another computer. Is this in fact the way to copy databases?
> After copying everything works except for example \dt , \di which gives the
> following
> error:
>
> ERROR: cache lookup for userid 1003 failed
>
> What does this mean?

Create user (createuser) with id 1003 in new database.

Vadim