From: | Ottavio Campana <ottavio(at)campana(dot)vi(dot)it> |
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To: | Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: queston about locking |
Date: | 2007-09-21 09:53:54 |
Message-ID: | 46F394B2.6000306@campana.vi.it |
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Thread: | |
Lists: | pgsql-general |
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.
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