Re: queston about locking

Albe Laurenz ha scritto:
> Ottavio Campana wrote:
>> I'm writing a python script to update some tables in a db. My
>> problem is
>> that I need to lock a couple of tables, perform several operations and
>> read the corresponding output.
>>
>> I was thinking about lock in exclusive mode, but in the
>> documentation I
>> found that it is valid only in a transaction. But since I need to
>> execute a command and read the output and so forth, I think I
>> cannot use
>> a transaction.
>>
>> What would you use to lock the table?
>
> What makes you think that you "need to lock a couple of tables"?

the point is that for each table I have a copy I previously made and I
want to create an incremental backup. My problem is that I don't want
the original table to change, so I lock it.

I admin that exclusive lock is probably too much.

Does share mode block inser/update/delete but allows reading?

Thanks.

PS: By the way, I just discovered that with python psycopg2 the cursor
is wrapped in a transaction, so locking works. So the problem is only
the correct lock level.