Re: Table lock while adding a column and clients are logged in - Mailing list pgsql-general

From Guillaume Lelarge
Subject Re: Table lock while adding a column and clients are logged in
Date
Msg-id 4D96EE95.2000209@lelarge.info
Whole thread Raw
In response to Table lock while adding a column and clients are logged in  ("Sven Haag" <sven-haag@gmx.de>)
Responses Re: Table lock while adding a column and clients are logged in
List pgsql-general
Le 02/04/2011 11:09, Sven Haag a écrit :
> hello pg fans,
>
> we have an application that communicates via ODBC directly to the postgres database.
>
> if i'm trying to add an additional column to a table in pgadmin while clients are logged in, pgadmin hangs. only if
allcients are logged out it returns to the normal state. according to our consultant of the application this behavior
doesn'tappear in oracle or sql-server. 
>
> how can i avoid this?
>

When you add a new column to a table, the session needs an
AccessExclusiveLock to this table, which means no one can have a lock on
the object while you add the column. IOW, pgAdmin (and any other tool)
will hang until no one works on the table. If it's a heavily used table,
there's not much you can do about it, but wait.


--
Guillaume
 http://www.postgresql.fr
 http://dalibo.com

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