I'm using 9.1 Will foreign data wrapper have similar performance issue as dblink? Thanks, Wendy -----Original Message----- From: Ian Barwick [mailto:ian@xxxxxxxxxxxxxxx] Sent: Sunday, January 04, 2015 3:13 PM To: Zheng, Wendy; pgsql-admin@xxxxxxxxxxxxxx Subject: Re: The quickest way to migrate database within the same cluster On 15/01/04 15:52, Zheng, Wendy wrote: > Hi PgSql experts, > > I'm working on a task to move tables from on database to another > within the same cluster and same server. I try the pg_dump and > pg_restore commands (with -Fc option), and notice that it costs around > half an hour which is not acceptable. Then I try to move the data > files directly. I create the same tables in the new DB, find out the > directory stores the data file and search for the data files by the > table name, then move the corresponding data file in the old DB to the > new one. This is very quick, and looks like the DB still works. But I > have a concern that whether there will any other problem if I doing this? Yes, you'll experience massive data corruption. You can't just manually copy data files around, even though it might seem to work. > Another workaround is to access the old DB in the new DB with dblink > (I created a view with dblink and use it as if the view as if the > table is in the new DB). But we soon notice that even though we > specify the criteria in the select command, dblink will still retrieve > all the records first, and then apply the search criteria. This brings > poor performance. Do you have any better idea how can I handle this? Which PostgreSQL version are you using? If 9.3 or later you can use a foreign data wrapper (postgres_fdw) to access data in another database (including on the same cluster). Regards Ian Barwick -- Ian Barwick http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, RemoteDBA, Training & Services -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
