Please send your answer (also) to the list. Le 28/11/2010 10:23, zhipan Wang a écrit : > [...] > Thanks a lot for your detailed reply. I am trying to implement the idea > proposed > in the paper Database Cracking. The basic idea is like this: > > When a query with a range predicate like "a<col" comes, a copy of the column > col > is created as a stand-alone table, and I need to partially sort (so > physically > reorganize) the table, and insert a node into the index to point to a tuple > in > the table, such that all values in the new table before that tuple are less > than a and all values in col after that tuple are greater than or equal to a. > As > more and more queries come in, the table becomes better ordered, and a qeury > can > benefit from sequential scan enabled by this order. >
Finding a solution to your issue is quite hard, because we don't know which issue you have. Anyways, some thoughts... PostgreSQL can already use an index to quickly sort a table. But CLUSTER may be a more appropriate solution for you. You have to remember that you'll need to launch CLUSTER from time to time so that the table get reorganized. > So the in-place update is a vital part of the program, because a range of > values > of column col should be stored together on the disk. Is there any way to do > such > a in-place update without generating much extra overhead? > If you need in-place update, then it's possible that PostgreSQL is not the right tool for you. But, as I already said, it's difficult to know for sure as we don't know what issue you're trying to fix. -- Guillaume http://www.postgresql.fr http://dalibo.com -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
