Le 21/02/2011 01:53, Tatsuo Ishii a écrit : >> Le 18/02/2011 02:21, Tatsuo Ishii a écrit : >>> Hi hackes, >>> >>> After my talk of pgpool-II V3 at FOSDEM 2011, I got a question about >>> the idea "partial replication", which allows to replicate part of >>> a database cluster in replication mode. >>> >>> This has been on my personal TODO list for years, and I start to think >>> about the implementation design again. >>> >>> - We could have "database level partial replication" and "table level >>> partial replication". >>> >>> - "Database level partial replication" is easy to do. Just having a >>> list of databases to replicate (or not to replicate) and >>> pool_where_to_send() will look it. However cross database tables >>> such as pg_database must be always replicated. >>> >>> - "Table level partial replication" is not so easy. In addition to >>> having a list of tables to replicate (or not to replicate), we would >>> want to have such a list for schemas. >>> >>> - If we have such a schema list, we need to know which schema the >>> table belogs to. This is not super easy if the table is not schema >>> qualified but doable. >>> >>> - Functions would be troublesome because we cannot know which table it >>> is going to write. >>> >>> Just my memorandum. Please feel free to add comments. >> >> As you say, databases would be easy. >> >> I don't see an easy way to configure table names. Using a text file >> would be a burden if the user has a big number of tables. If you want to >> have such a feature, we need to provide a way to easyly configure the >> replication feature. We already have a system DB available. We could >> probably use it to "register" the tables to replicate. > > Year to store large configuration data, we could use PostgreSQL > itself. One thing I want to do is, getting ride of system DB. We could > use one of DB nodes for this purpose, no? >
We need to have this on each node. It would be really sad if the only node with the information just crash. > Another problem we have to resolve is, online recovery. Probably we > need to wait for the day when PostgreSQL can do the base backup > partialy. Meaning we'll wait quite a long time. Partial replication is a long way to go. -- Guillaume http://www.postgresql.fr http://dalibo.com _______________________________________________ Pgpool-hackers mailing list Pgpool-hackers@pgfoundry.org http://pgfoundry.org/mailman/listinfo/pgpool-hackers
