[GRASSLIST:3615] Disconnecting db in 5.7

GRASS GRASS user
1

A few days ago, I ran an overlay command and then linked the output up
to an attribute table:

v.overlay ainput=l1ashp atype=area binput=curregion btype=area
output=l1ashp2cut operator=and

v.db.connect -o map=l1ashpcut table=l1aatt key=LINK_KEY \
    driver=pg database="dbname=jogis,user=caumann"

Today, I tried to re-run things and got the following error:

GRASS 5.7.-cvs:~/grass57/netdown/jogis/caumann/vector > v.overlay
ainput=l1ashp atype=area binput=curregion btype=area output=l1ashpcut \

    operator=and

-----------------------------------------------------------------------------
Writing attributes ...
DBMI-DBF driver error:
Table l1ashpcut already exists
Error in db_execute_immediate()

ERROR: Cannot create table: create table l1ashpcut (cat integer, cata
       integer, catb integer)

--------------

No matter what I do, I can't make this error go away. I suspect I
should have done something to disconnect the db before I re-ran this.

What am I not understanding/not doing right?

Thanks!
Craig

2

On Monday 07 June 2004 22:50, Craig Aumann wrote:

A few days ago, I ran an overlay command and then linked the output up
to an attribute table:

v.overlay ainput=l1ashp atype=area binput=curregion btype=area
output=l1ashp2cut operator=and

It was output=l1ashpcut, I presume?

v.db.connect -o map=l1ashpcut table=l1aatt key=LINK_KEY \
    driver=pg database="dbname=jogis,user=caumann"

Today, I tried to re-run things and got the following error:

GRASS 5.7.-cvs:~/grass57/netdown/jogis/caumann/vector > v.overlay
ainput=l1ashp atype=area binput=curregion btype=area output=l1ashpcut \

> operator=and

---------------------------------------------------------------------------
-- Writing attributes ...
DBMI-DBF driver error:
Table l1ashpcut already exists
Error in db_execute_immediate()

ERROR: Cannot create table: create table l1ashpcut (cat integer, cata
       integer, catb integer)

--------------

No matter what I do, I can't make this error go away. I suspect I
should have done something to disconnect the db before I re-ran this.

What am I not understanding/not doing right?

v.db.connect must be used with attention and understanding what it does.
In general it creates/deletes links to tables, but doe not create/drop/copy
the table.

v.overlay created a new table 'l1ashpcut' linked to field 1,
then you relinked the field 1 (v.db.connect -o map=l1ashpcut table=l1aatt),
to the table 'l1aatt', the table 'l1ashpcut' however remains in the database.
When you run 'v.overlay output=l1ashpcut' second time, it first deletes
old existing vector 'l1ashpcut' and all its tables (in this case only
the table 'l1aatt', which you linked by v.db.connect).
The table 'l1ashpcut' was not deleted because the link to this table
was overwritten by 'v.db.connect -o' so the vector 'l1ashpcut' knows
nothing about that table.

You have to run something like
echo 'drop table l1ashpcut' | db.execute
for example, to delete the table.

Radim

3

Thanks, Radim! This clears things up for me.

And yes, the output below should have been "l1ashpcut" and not my
work-around "l1ashp2cut".

Cheers!
Craig

On Tue, 2004-06-08 at 06:40, Radim Blazek wrote:

On Monday 07 June 2004 22:50, Craig Aumann wrote:
> A few days ago, I ran an overlay command and then linked the output up
> to an attribute table:
>
> v.overlay ainput=l1ashp atype=area binput=curregion btype=area
> output=l1ashp2cut operator=and

It was output=l1ashpcut, I presume?

> v.db.connect -o map=l1ashpcut table=l1aatt key=LINK_KEY \
> driver=pg database="dbname=jogis,user=caumann"
>
>
> Today, I tried to re-run things and got the following error:
>
> GRASS 5.7.-cvs:~/grass57/netdown/jogis/caumann/vector > v.overlay
> ainput=l1ashp atype=area binput=curregion btype=area output=l1ashpcut \
>
> > operator=and
>
> ---------------------------------------------------------------------------
>-- Writing attributes ...
> DBMI-DBF driver error:
> Table l1ashpcut already exists
> Error in db_execute_immediate()
>
> ERROR: Cannot create table: create table l1ashpcut (cat integer, cata
> integer, catb integer)
>
> --------------
>
> No matter what I do, I can't make this error go away. I suspect I
> should have done something to disconnect the db before I re-ran this.
>
> What am I not understanding/not doing right?

v.db.connect must be used with attention and understanding what it does.
In general it creates/deletes links to tables, but doe not create/drop/copy
the table.

v.overlay created a new table 'l1ashpcut' linked to field 1,
then you relinked the field 1 (v.db.connect -o map=l1ashpcut table=l1aatt),
to the table 'l1aatt', the table 'l1ashpcut' however remains in the database.
When you run 'v.overlay output=l1ashpcut' second time, it first deletes
old existing vector 'l1ashpcut' and all its tables (in this case only
the table 'l1aatt', which you linked by v.db.connect).
The table 'l1ashpcut' was not deleted because the link to this table
was overwritten by 'v.db.connect -o' so the vector 'l1ashpcut' knows
nothing about that table.

You have to run something like
echo 'drop table l1ashpcut' | db.execute
for example, to delete the table.

Radim