Re: Need help for our thesis. - Mailing list pgsql-hackers
From | Hans-Jürgen Schönig |
---|---|
Subject | Re: Need help for our thesis. |
Date | |
Msg-id | 3F07F044.3080203@cybertec.at Whole thread Raw |
In response to | Need help for our thesis. (MIka Santos <only_mhe@yahoo.com>) |
List | pgsql-hackers |
Hello Mika Currently you can use dblink which queries a remote database and returns the data as a table. This works nicely for PostgreSQL. There is also a JDBC version in progress. We have writte an Oracle version of dblink. SELECT * FROM dblink('connectstr', 'SELECT ...') AS some_type; This works nicely. Still, this is not a full implementation of distributed queries - this would be a huge project. There has already been some discussion about that on the hackers list. Regards, Hans Richard Schilling wrote: > As luck would have I've put some thought into this problem before as > well. Having reviewed the code quite a bit, and played around with the > backend, my intuition tells me that the following would work. > > Write a custom "cluster-aware" postmaster so it distributes queries to > various machines. Of course each machine would have to be running a > normal postmaster to receive the queries. And, the cluster-aware > postmaster would need to be informed of which machines to submit queries > to (e.g. listed in a configuration file). Queries could be processed in > the following ways: > > * database management queries (e.g. create database, create table, > alter table, etc. . . ) would be distributed to every machine > * select queries would be distributed to every machine. The > cluster-aware postmaster would merge the results before delivering them > to the client. > * an insert query would go to one machine only, and the > cluster-aware postmaster could switch between the designated machines > after each insert. For example, given two machines, the first insert > would go to machine A, the second to machine B, etc . . . > > Don't know if that's been tried, but that's where I would start. > Postgres' modular design of a postmaster and a backend would make this > relatively easy to do, because the only thing you might end up writing > is the one cluster-aware postmaster. If you end up doing this let me > know and if I have time I'll help out with the design/coding. > > Richard Schilling > Lake Stevens, WA USA > > > > On 2003.07.04 18:56 MIka Santos wrote: > >> Gud day! We are currently having our thesis for our undergarduate >> course and this involoves the code of PostgreSQL. Basically, our >> thesis needs a modification of the existing code of the said database. >> As of now, our University has an existing online registration system >> which uses Postgre as their back end. But the problem is the existing >> one is not a distributed system. Our thesis adviser would like us to >> deal with the load balancing of the said online registration. He >> wanted a multidatabase querying. For example, we knew that the >> following statements are posible, >> select * >> from t1, t2., t3; >> provided that t1 and t2, t3 are tables from a single database. >> Our thesis is to make the following satatement legal >> select * >> from d1, d2, d3; >> provided that d1 and d2, d3 are separate databases. >> We are currently having our research about this problem and as >> beginners, we surely need help from experts like you. Any form of >> comments and suggestions will surely be appreciated by the group. >> Thank you very much and hope to here from you. -- Cybertec Geschwinde u Schoenig Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria Tel: +43/2952/30706; +43/664/233 90 75 www.cybertec.at, www.postgresql.at, kernel.cybertec.at
pgsql-hackers by date: