Hi Jonathan, You need to be pretty cautious about this but basically if both databases are up you can select across them. The problem is that if one of your databases is being recovered or restored, you might get a syntax error (bad) or inconsistent data due to one database being out of date (worse).
One of the long-range features I would like to add to Sequoia is ability to work at the level of a server rather than databases. This requires some careful thought to ensure we can still recovery everything correctly. For now you can't update across databases. Selects are ok if you are very careful. Thanks, Robert On 3/10/08 12:58 PM, "Jonathan Poole" <[EMAIL PROTECTED]> wrote: > Insert's I can understand, how about joins? Can we join tables from > multiple database connections? > > Ie, > > Controller -> vdbA -> table 1 > -> vdbB -> table 2 > > So basically we cannot do an insert into table 1, via vdbB's connection. > This is fine, I understand the table locking, how about reads, or any > other types of queries. Should I be cautious of other types of queries > in the future? If so, what types? > > Can we do join's of table 1 and table 2, regardless of what connection > we go down? > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Emmanuel Cecchet > Sent: Monday, March 10, 2008 10:11 AM > To: Sequoia general mailing list > Subject: Re: [Sequoia] SQL Query > > Hi Jonathan, > > I am not sure I completely got your use case but if you are trying to > create a single database db1 and execute things like 'INSERT INTO > db2.table VALUES ...' through db1, Sequoia will not be able to find out > the db2 tables. With JDBC, you can only fetch tables from the database > you are connected to (not the entire RDBMS schema). So Sequoia will not > be able to perform the proper locking and ensure consistency on db2 > tables in that case. > > Hope this helps, > Emmanuel > >> I have been using limited resources, so I've had to create a >> controller with a virtual database writing to the same sql database >> with databases db1_databasename, db2_databasename. If this is the case > >> I assume I can just take out the second database out of my virtual >> database configuration file and have the same database name as my >> virtual database name and things should work like a charm? Will I >> loose all raidb1 functionality? I'll find another server to have true, > >> two databases working with sequoia in a proper setup. But as I said, >> resources right now are slim. >> >> > ------------------------------------------------------------------------ >> >> *From:* [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] *On Behalf Of >> *Robert Hodges >> *Sent:* Friday, March 07, 2008 4:45 PM >> *To:* Sequoia general mailing list >> *Subject:* Re: [Sequoia] SQL Query >> >> Hi Jonathan, >> >> No apology necessary. Is the vdb name the same as your database name? >> If you match them I think it should work. >> >> Thanks, Robert >> >> >> On 3/7/08 1:31 PM, "Jonathan Poole" <[EMAIL PROTECTED]> wrote: >> >> Hello All, >> >> I really apologize fro the noise I cause on this list, but anyhow I'm >> running into the following now. >> >> Issuing the following commands via the sql client performs some >> behavior that I'm wondering if there is a workaround for or if queries > >> will have be specially constructed to work with sequoia (My hope is >> that it's completely transparent) >> >> jdbc:sequoia://192.168.61.14:25324/virtualdb (user) > select >> CUSTOMER_ID from CUSTOMERS; >> +------------+ >> | LICENSE_ID | >> +------------+ >> | 1 | >> | 2 | >> | 3 | >> | 5 | >> +------------+ >> >> Query executed in 0 s 1 ms . >> >> This is great, however when some queries are constructed with >> databasename.customers such as >> >> >> jdbc:sequoia://192.168.61.14:25324/virtualdb (user) > select >> CUSTOMER_ID from virtualdb.CUSTOMERS; >> An error occured while executing SQL query >> (org.continuent.sequoia.common.exceptions.driver.DriverSQLException: >> Message of cause: Request select CUSTOMER_ID from virtualdb.cust_... >> failed on backend DB1 (Table 'virtualdb.CUSTOMERS' doesn't exist)) >> jdbc:sequoia://192.168.61.14:25324/virtualdb (user) > >> >> Any help would be appreciated. >> >> Regards, >> Jonathan D. Poole >> >> > ------------------------------------------------------------------------ >> >> _______________________________________________ >> Sequoia mailing list >> [email protected] >> https://forge.continuent.org/mailman/listinfo/sequoia >> >> >> >> -- >> Robert Hodges, CTO, Continuent, Inc. >> Email: [EMAIL PROTECTED] >> Mobile: +1-510-501-3728 Skype: hodgesrm >> > > _______________________________________________ > Sequoia mailing list > [email protected] > https://forge.continuent.org/mailman/listinfo/sequoia > > _______________________________________________ > Sequoia mailing list > [email protected] > https://forge.continuent.org/mailman/listinfo/sequoia -- Robert Hodges, CTO, Continuent, Inc. Email: [EMAIL PROTECTED] Mobile: +1-510-501-3728 Skype: hodgesrm _______________________________________________ Sequoia mailing list [email protected] https://forge.continuent.org/mailman/listinfo/sequoia
